Light-emitting diode for display and display device having them

Abstract

To provide a light-emitting diode for a display, that permits an increase of a light emitting area of each subpixel without increasing a pixel area.SOLUTION: A light-emitting diode for a display, contains: a support substrate 51; a first LED stack 23; a second LED stack 33; and a third LED stack 43, in which a first color filter 37 is interposed between the first and second LED stacks, and makes light generated from the first LED stack transmit while reflecting the light generated from the second LED stack, a second color filter 47 is interposed between the second and third LED stacks, and makes the light generated from the first and second LED stacks transmit while reflecting the light generated from the third LED stack, the light generated from the first LED stack is discharged to an external part via the second and third LED stacks, and the light generated from the second LED stack is discharged to the external part via the third LED stack.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure relate to light-emitting diodes for next-generation displays and display devices having the same. [Background technology]

[0002] Light emitting diodes (LEDs) have been used as inorganic light sources in various fields, including displays, vehicle lamps, general lighting, etc. Due to various advantages such as long life, low power consumption, and fast response, LEDs have replaced existing light sources in the industry.

[0003] Although typical light-emitting diodes have been used as backlight sources in display devices, microLED displays have recently been developed as next-generation displays that are configured to directly realize images using light-emitting diodes.

[0004] Generally, a display device realizes various hues by mixing blue, green, and red light. In a display device, each pixel includes sub-pixels corresponding to blue, green, and red hues, respectively, and an image can be realized by combining such pixels by determining the hue of a particular pixel based on the hues of these sub-pixels.

[0005] In a micro LED display, micro LEDs are arranged on a two-dimensional plane corresponding to sub-pixels, so multiple micro LEDs must be arranged on a single substrate. However, micro LEDs have very small dimensions of less than 200 μm or less than 100 μm, which causes various problems. In particular, it is difficult to mount micro LEDs on a display panel due to the difficulty in handling micro LEDs, and it is also difficult to replace defective micro LEDs on a display panel with new micro LEDs.

[0006] In addition, since the subpixels are arranged in a two-dimensional plane within the display, one pixel including subpixels for blue, green, and red hues occupies a relatively large area. Therefore, in order to arrange the subpixels within a limited area, the area of ​​each subpixel must be reduced, which leads to a decrease in brightness due to a decrease in the light-emitting area.

[0007] However, there is a large difference in visibility for blue, green, and red hues. In particular, the visibility for green hues is much higher than that for red hues. As a result, even when light-emitting diodes (LEDs) emit the same radiant flux, differences in brightness occur depending on the hue. To reduce the brightness difference due to visibility, the area of ​​the LED that emits hues with low visibility can be increased. However, as the area of ​​the LED increases, the area occupied by the subpixel also increases.

[0008] In addition, the difference in brightness can be reduced by adjusting the current density applied to each LED, but reducing the difference in brightness due to visibility by adjusting the current density makes the display operation complicated and difficult. Therefore, for display devices using micro LEDs, it is necessary to develop technology that enables micro LEDs to emit light of similar brightness without significantly changing the area occupied by the micro LED in a two-dimensional plane or the current density applied to the micro LED.

[0009] The information disclosed in this Background section is intended merely to provide background understanding of the inventive concepts and, as such, may include information that does not constitute prior art. Summary of the Invention [Problem to be solved by the invention]

[0010] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display, and a display device having the same, that allows an increase in the light-emitting area of ​​each sub-pixel without increasing the pixel area.

[0011] Exemplary embodiments of the present disclosure provide a display light emitting diode and a display device having the same that do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0012] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display, and a display device having the same, that allows an increase in the light-emitting area of ​​each sub-pixel without increasing the pixel area.

[0013] Exemplary embodiments of the present disclosure provide a display light emitting diode and a display device having the same that do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0014] Exemplary embodiments of the present disclosure provide light emitting diode pixels for displays and display devices including the same that do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0015] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display that allows an increase in the light-emitting area of ​​each sub-pixel without increasing the pixel area, and a display device including the same.

[0016] Exemplary embodiments of the present disclosure provide a display light emitting diode and a display device including the same, which do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0017] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light emitting diode for a display, and a display device including the same, capable of adjusting light emission in consideration of visibility.

[0018] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display, and a display device having the same, that allows an increase in the light-emitting area of ​​each sub-pixel without increasing the pixel area.

[0019] Exemplary embodiments of the present disclosure provide a display light emitting diode and a display device having the same that do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0020] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display, and a display device having the same, capable of adjusting light emission in consideration of visibility. [Means for solving the problem]

[0021] According to one exemplary embodiment of the present disclosure, a light-emitting diode stack for a display includes a support substrate, a first LED stack disposed on the support substrate, a second LED stack disposed on the first LED stack, a third LED stack disposed on the second LED stack, a conductive growth substrate coupled to the second LED stack or the third LED stack, a first color filter interposed between the first LED stack and the second LED stack and transmitting light generated from the first LED stack while reflecting light generated from the second LED stack, and a second color filter interposed between the second LED stack and the third LED stack and transmitting light generated from the first and second LED stacks while reflecting light generated from the third LED stack, wherein the light generated from the first LED stack is emitted to the outside through the second LED stack, the third LED stack, and the conductive growth substrate, and the light generated from the second LED stack is emitted to the outside through the third LED stack and the conductive growth substrate.

[0022] According to another exemplary embodiment of the present disclosure, a display device includes a plurality of pixels arranged on a support substrate, each pixel including: a first LED stack arranged on the support substrate; a second LED stack arranged on the first LED stack; a third LED stack arranged on the second LED stack; a conductive growth substrate coupled to the second LED stack or the third LED stack; a first color filter interposed between the first LED stack and the second LED stack and transmitting light generated from the first LED stack while reflecting light generated from the second LED stack; and a second color filter interposed between the second LED stack and the third LED stack and transmitting light generated from the first and second LED stacks while reflecting light generated from the third LED stack, wherein the light generated from the first LED stack is emitted to the outside through the second LED stack, the third LED stack, and the conductive growth substrate, and the light generated from the second LED stack is emitted to the outside through the third LED stack and the conductive growth substrate.

[0023] According to one exemplary embodiment of the present disclosure, a light-emitting diode stack for a display includes a first LED stack including a first conductive type semiconductor layer and a second conductive type semiconductor layer, a second LED stack disposed on the first LED stack, a third LED stack disposed on the second LED stack, an ohmic electrode disposed on the opposite side of the second LED stack and forming ohmic contact with the first conductive type semiconductor layer of the first LED stack, and a reflective electrode disposed on the opposite side of the second LED stack and forming ohmic contact with the second conductive type semiconductor layer of the first LED stack, wherein light generated from the first LED stack is emitted to the outside via the second LED stack and the third LED stack, and light generated from the second LED stack is emitted to the outside via the third LED stack.

[0024] According to another exemplary embodiment of the present disclosure, a display device includes a plurality of pixels arranged on a supporting substrate, each pixel including: a first LED stack disposed on the supporting substrate and including a first conductive type semiconductor layer and a second conductive type semiconductor layer; a second LED stack disposed on the first LED stack; a third LED stack disposed on the second LED stack; an ohmic electrode interposed between the substrate and the first conductive type semiconductor layer of the first LED stack and forming an ohmic contact with the first conductive type semiconductor layer of the first LED stack; and a reflective electrode interposed between the substrate and the second conductive type semiconductor layer of the first LED stack and forming an ohmic contact with the second conductive type semiconductor layer of the first LED stack, wherein light generated from the first LED stack is emitted to the outside via the second LED stack and the third LED stack, and light generated from the second LED stack is emitted to the outside via the third LED stack.

[0025] According to one exemplary embodiment of the present disclosure, a light-emitting diode pixel for a display includes a first LED stack, a second LED stack disposed within a partial area on the first LED stack, a third LED stack disposed within a partial area on the second LED stack, and a reflective electrode disposed below the first LED stack, wherein each of the first to third LED stacks includes an n-type semiconductor layer and a p-type semiconductor layer, and all of the n-type semiconductor layers of the first to third LED stacks are electrically connected to the reflective electrode, and the first LED stack, the second LED stack, and the third LED stack are independently drivable.

[0026] According to another exemplary embodiment of the present disclosure, a display device includes a plurality of pixels arranged on a support substrate, each pixel including a first LED stack, a second LED stack disposed within a partial area on the first LED stack, a third LED stack disposed within a partial area on the second LED stack, and a reflective electrode disposed below the first LED stack, each of the first to third LED stacks including an n-type semiconductor layer and a p-type semiconductor layer, all of the n-type semiconductor layers of the first to third LED stacks being electrically connected to the reflective electrode, and the first LED stack, the second LED stack, and the third LED stack being independently driven.

[0027] According to one exemplary embodiment of the present disclosure, a light emitting diode stack for a display includes a 1-1 LED stack, a 1-2 LED stack disposed on the 1-1 LED stack, a second LED stack disposed on the 1-2 LED stack, and a third LED stack disposed on the second LED stack, wherein the 1-1 LED stack and the 1-2 LED stack are adapted to emit red light, the second LED stack is adapted to emit green light, and the third LED stack is adapted to emit blue light.

[0028] According to another exemplary embodiment of the present disclosure, a display device includes a plurality of pixels arranged on a support substrate, each pixel including a 1-1 LED stack disposed on the support substrate, a 1-2 LED stack disposed on the 1-1 LED stack, a second LED stack disposed on the 1-2 LED stack, and a third LED stack disposed on the second LED stack, wherein the 1-1 LED stack and the 1-2 LED stack are adapted to emit red light, the second LED stack is adapted to emit green light, and the third LED stack is adapted to emit blue light.

[0029] According to another exemplary embodiment of the present disclosure, a light emitting diode stack for a display includes a 1-1 LED stack, a 1-2 LED stack disposed on the 1-1 LED stack, a second LED stack disposed on the 1-2 LED stack, and a third LED stack disposed on the second LED stack, wherein the 1-1 LED stack and the 1-2 LED stack include AlGaInP-based well layers, the second LED stack is adapted to emit light having a shorter wavelength than the 1-1 and 1-2 LED stacks, and the third LED stack is adapted to emit light having a shorter wavelength than the second LED stack.

[0030] According to one exemplary embodiment of the present disclosure, a light emitting diode stack for a display includes a first LED stack, a second LED stack disposed on the first LED stack, and a third LED stack disposed on the second LED stack, wherein the first LED stack has a multi-junction LED stack structure.

[0031] According to another exemplary embodiment of the present disclosure, a display device includes a plurality of pixels arranged on a support substrate, each pixel including a first LED stack disposed on the support substrate, a second LED stack disposed on the first LED stack, and a third LED stack disposed on the second LED stack, wherein the first LED stack has a multi-junction LED stack structure.

[0032] One exemplary embodiment of the present disclosure provides a light-emitting diode stack for a display, the light-emitting diode stack including: a support substrate, a first LED stack disposed on the support substrate, a second LED stack disposed on the first LED stack, a third LED stack disposed on the second LED stack, a conductive growth substrate coupled to the second LED stack or the third LED stack, a first color filter interposed between the first and second LED stacks and transmitting light generated from the first LED stack while reflecting light generated from the second LED stack, and a second color filter interposed between the second and third LED stacks and transmitting light generated from the first and second LED stacks while reflecting light generated from the third LED stack, wherein the light generated from the first LED stack is emitted to the outside via the second and third LED stacks and the conductive growth substrate, and the light generated from the second LED stack is emitted to the outside via the third LED stack and the conductive growth substrate.

[0033] The structure in which the first to third LED stacks are stacked on top of each other allows the light-emitting diode stack to increase the light-emitting area of ​​each subpixel without increasing the pixel area. In addition, the first and second color filters allow the light generated from the first LED stack to be emitted to the outside through the second LED stack and the third LED stack, allow the light generated from the second LED stack to be emitted to the outside through the third LED stack, and prevent the light generated from the second LED stack from entering the first LED stack and prevent the light generated from the third LED stack from entering the second LED stack, thereby improving light-emitting efficiency.

[0034] Additionally, the growth substrate for the second or third LED stack can remain instead of being removed, allowing for simplification of the manufacturing process. However, it should be understood that the present disclosure is not limited in this respect. In other exemplary embodiments, the growth substrate can be removed.

[0035] In particular, the light emitting diode stack can include a conductive growth substrate coupled to the second LED stack and the third LED stack, respectively.

[0036] Meanwhile, the first, second, and third LED stacks can be arranged in sequence and emit light having wavelengths that gradually decrease in that order. For example, the first, second, and third LED stacks can emit red light, green light, and blue light, respectively. Because the first, second, and third LED stacks emit light having wavelengths that gradually decrease in that order, optical interference between the LED stacks can be prevented.

[0037] Each of the first and second color filters may be a low-pass filter, a band-pass filter, or a band-stop filter. In particular, each of the first and second color filters may include an insulating layer having a different refractive index. By including an insulating layer in the first and second color filters, the LED stack may have structural stability and exhibit good light-emitting efficiency. For example, each of the first and second color filters may be a band-stop filter including a distributed Bragg reflector.

[0038] The conductive growth substrate may be a Si-doped GaN-based substrate. The GaN-based substrate used as the growth substrate can reduce the dislocation density of the second or third LED stack grown thereon. The second or third LED stack can have a dislocation density of, for example, 103 to 107 / cm2. As a result, the luminous efficiency of the second or third LED stack can be improved.

[0039] The first LED stack, the second LED stack, and the third LED stack are sequentially stacked on the support substrate via the first bonding layer, the second bonding layer, and the third bonding layer, which may be a transparent inorganic insulating layer, a transparent organic insulating layer, or a transparent conductive layer.

[0040] In one exemplary embodiment, the light-emitting diode stack for a display may additionally include a first bonding layer interposed between the support substrate and the first LED stack, a second bonding layer interposed between the first LED stack and the first color filter, and a third bonding layer interposed between the second LED stack and the second color filter, wherein the second bonding layer transmits light generated from the first LED stack, and the third bonding layer transmits light generated from the first and second LED stacks. The first to third bonding layers enable the first LED stack, the second LED stack, and the third LED stack to be bonded to each other while allowing light to be emitted to the outside through the second and third bonding layers, thereby preventing light loss.

[0041] The first to third LED stacks can be driven independently, and therefore the light emitting diode stack can be provided with electrodes having various structures.

[0042] In one exemplary embodiment, the light-emitting diode stack for a display may further include: a first-p reflective electrode interposed between the first bonding layer and the first LED stack and forming an ohmic contact with a p-type semiconductor layer of the first LED stack; a second-p transparent electrode interposed between the first color filter and the second LED stack and forming an ohmic contact with a p-type semiconductor layer of the second LED stack; and a third-p transparent electrode interposed between the second color filter and a third LED stack and forming an ohmic contact with a p-type semiconductor layer of the third LED stack, wherein light generated from the first LED stack is emitted to the outside through the second-p transparent electrode and the third-p transparent electrode, and light generated from the second LED stack is emitted to the outside through the third-p transparent electrode. The first-p reflective electrode, the second-p transparent electrode, and the third-p transparent electrode can help current spreading in the light-emitting diode stack. In addition, the first-p reflective electrode can improve light emitting efficiency by reflecting light generated from the first LED stack so that it is emitted to the outside, and the second-p transparent electrode and the third-p transparent electrode transmit light generated from the LED stack to prevent light loss.

[0043] The second bonding layer may be adjacent to the n-type semiconductor layer of the first LED stack, and the third bonding layer may be adjacent to a conductive growth substrate that is bonded to the second LED stack.

[0044] In another exemplary embodiment, the light-emitting diode stack for a display may additionally include a first bonding layer interposed between the support substrate and the first LED stack, a second bonding layer interposed between the first color filter and the second LED stack, and a third bonding layer interposed between the second LED stack and the second color filter, wherein the second bonding layer and the third bonding layer transmit light generated from the first LED stack and the second LED stack.

[0045] In addition, the light-emitting diode stack for a display may additionally include: a first-n reflective electrode interposed between the first bonding layer and the first LED stack and forming an ohmic contact with the n-type semiconductor layer of the first LED stack; a first-p transparent electrode interposed between the first LED stack and the first color filter and forming an ohmic contact with the p-type semiconductor layer of the first LED stack; a second-p transparent electrode interposed between the second LED stack and the third bonding layer and forming an ohmic contact with the p-type semiconductor layer of the second LED stack; and a third-p transparent electrode interposed between the second color filter and the third LED stack and forming an ohmic contact with the p-type semiconductor layer of the third LED stack, wherein light generated from the first LED stack is emitted to the outside via the first-p transparent electrode, the second-p transparent electrode, and the third-p transparent electrode, and light generated from the second LED stack is emitted to the outside via the second-p transparent electrode and the third-p transparent electrode.

[0046] According to yet another exemplary embodiment of the present disclosure, there is provided a display device including a plurality of pixels arranged on a support substrate, each pixel including a first LED stack arranged on the support substrate, a second LED stack arranged on the first LED stack, a third LED stack arranged on the second LED stack, a conductive growth substrate coupled to the second LED stack or the third LED stack, a first color filter interposed between the first and second LED stacks and transmitting light generated from the first LED stack while reflecting light generated from the second LED stack, and a second color filter interposed between the second and third LED stacks and transmitting light generated from the first and second LED stacks while reflecting light generated from the third LED stack, wherein the light generated from the first LED stack is emitted to the outside via the second LED stack, the third LED stack, and the conductive growth substrate, and the light generated from the second LED stack is emitted to the outside via the third LED stack and the conductive growth substrate.

[0047] The display device may also include a conductive growth substrate coupled to the second and third LED stacks, respectively.

[0048] Each of the first color filter and the second color filter may be a low-pass filter, a band-pass filter, or a band-stop filter.

[0049] The conductive growth substrate may be a Si-doped GaN-based substrate.

[0050] In each pixel, the p-type semiconductor layers of the first, second, and third LED stacks are electrically connected to a common line, and the n-type semiconductor layers are electrically connected to different lines, for example, the common line may be a data line, and the different lines may be scan lines.

[0051] The display device may additionally include a lower insulating layer covering the sides of the first, second and third LED stacks, and the lower insulating layer may include openings for electrical connections.

[0052] The lower insulating layer may include distributed Bragg reflectors that reflect red, green, and blue light.

[0053] In one exemplary embodiment, the display device may further include a reflective electrode interposed between the support substrate and the first LED stack, the reflective electrode being continuously disposed above the plurality of pixels to be used as a common line.

[0054] In another exemplary embodiment, the display device may further include reflective electrodes interposed between the support substrate and the first LED stack, and each reflective electrode may be confined within each pixel area.

[0055] The display device may additionally include a first bonding layer interposed between the support substrate and the first LED stack, a second bonding layer interposed between the first LED stack and the second LED stack, and a third bonding layer interposed between the second LED stack and the second color filter, wherein the second bonding layer transmits light generated from the first LED stack and the third bonding layer transmits light generated from the first and second LED stacks.

[0056] The first bonding layer, the second bonding layer, and the third bonding layer may be a transparent inorganic insulating layer, a transparent organic insulating layer, or a transparent conductive layer.

[0057] In each pixel, the first to third LED stacks can be driven independently.

[0058] The present disclosure provides a light-emitting stack structure that has a simple structure and is easy to manufacture.

[0059] The present disclosure provides a display device having a light-emitting stack structure.

[0060] An embodiment of the inventive concept can provide a light emitting stack structure including a plurality of epitaxial stacks stacked one on top of the other to emit color lights having different wavelength bands, each epitaxial stack emitting a corresponding color light in an upward direction, the light emitting areas of the epitaxial stacks overlapping each other, and the lowest epitaxial stack among the epitaxial stacks has an uneven portion disposed on its upper surface.

[0061] Each epitaxial stack is independently drivable.

[0062] The colored lights emitted from the epitaxial stacks may have different energy bands, and the energy bands of the colored lights emitted from the epitaxial stacks gradually increase from the epitaxial stack located at the bottom to the epitaxial stack located at the top.

[0063] In two adjacent epitaxial stacks, colored light emitted from the lower epitaxial stack can travel through the upper epitaxial stack, and the epitaxial stack can transmit at least about 80% of the colored light from the epitaxial stack located below it.

[0064] The epitaxial stack may include a first epitaxial stack disposed on the substrate for emitting a first color light, a second epitaxial stack disposed on the first epitaxial stack for emitting a second color light having a different wavelength band than the first color light, and a third epitaxial stack disposed on the second epitaxial stack for emitting a third color light having a different wavelength band than the first and second color lights.

[0065] The first, second and third color lights may be red light, green light and blue light, respectively.

[0066] The light emitting stack may additionally include a first wavelength pass filter disposed between the first epitaxial stack and the second epitaxial stack.

[0067] The light emitting stack may additionally include a second wavelength pass filter disposed between the second epitaxial stack and the third epitaxial stack.

[0068] Each of the first, second, and third epitaxial stacks can include a p-type semiconductor layer disposed on a substrate, an active layer disposed on the p-type semiconductor layer, and an n-type semiconductor layer disposed on the active layer.

[0069] The n-type semiconductor layer of at least one of the second and third epitaxial stacks can include a textured portion disposed thereon.

[0070] The light emitting stack may additionally include first, second and third p-type electrodes connected to the p-type semiconductor layers of the first, second and third epitaxial stacks, respectively.

[0071] A first p-type electrode is disposed between the substrate and the first epitaxial stack.

[0072] The second p-type electrode is disposed between the first epitaxial stack and the second epitaxial stack, and can include a transparent conductive material.

[0073] The third p-type electrode is disposed between the second epitaxial stack and the third epitaxial stack, and can include a transparent conductive material.

[0074] The first, second and third p-type electrodes may substantially cover the first, second and third epitaxial stacks, respectively.

[0075] The light emitting stack structure may additionally include an insulating layer covering the third epitaxial stack and including a first contact hole provided therethrough to expose the top surfaces of the second and third p-type electrodes, and a second contact hole provided therethrough to expose the top surfaces of the second and third n-type semiconductor layers.

[0076] The first and second contact holes are provided in the peripheral area.

[0077] The light emitting stack may further include a data line for applying a common voltage to the first, second, and third p-type electrodes of the first, second, and third epitaxial stacks, the data line being connected to the first p-type electrode between the substrate and the first epitaxial stack and connected to the second and third p-type electrodes through the first contact holes.

[0078] The light emitting stack may further include first, second, and third signal lines for applying signals to the first, second, and third n-type semiconductor layers of the first, second, and third epitaxial stacks, respectively. The first signal line is connected to the first n-type semiconductor layer between the substrate and the first epitaxial stack, the second signal line is connected to the second n-type semiconductor layer through the second contact hole, and the third signal line is connected to the third n-type semiconductor layer through the second contact hole.

[0079] An embodiment of the present concept may provide a display device to which a light-emitting stack structure is applied. The display device includes a plurality of pixels. Each pixel includes a plurality of epitaxial stacks stacked in order on one another and emitting color light having different wavelength bands. Each epitaxial stack emits a corresponding color light upward, and light-emitting areas of the epitaxial stacks overlap each other. The epitaxial stacks located at the bottom of the epitaxial stacks may include a concave-convex portion located on an upper surface thereof.

[0080] The display device may further include a line part electrically connected to the pixel for applying a light emitting signal to the pixel.

[0081] The line portion may include a plurality of data lines extending in a first direction and connected to first semiconductor layers of the first, second, and third epitaxial stacks, and a plurality of signal lines extending in a second direction intersecting the first direction and connected to second semiconductor layers of the first, second, and third epitaxial stacks, respectively.

[0082] The display device can be driven in a passive matrix or active matrix manner.

[0083] As a result, the light emitting stack structure can have a simple structure and can be easily manufactured. Furthermore, a display device can include the light emitting stack structure.

[0084] The present disclosure provides a light-emitting stack structure that has a simple structure and is easy to manufacture.

[0085] An embodiment of the inventive concept can provide a light emitting stack structure including: a first epitaxial stack that emits a first color light; a second epitaxial stack disposed on the first epitaxial stack for emitting a second color light different from the first color light; and an electrode disposed on the second epitaxial stack and electrically connected to the first and second epitaxial stacks. The light emitting area of ​​the first epitaxial stack can overlap the light emitting area of ​​the second epitaxial stack, and the first and second epitaxial stacks can emit the first and second color lights downward.

[0086] The first color light can have a wavelength that is shorter than the wavelength of the second color light.

[0087] The first color light may be blue light, and the second color light may be red light.

[0088] The first and second epitaxial stacks are independently drivable.

[0089] At least one of the first epitaxial stack and the second epitaxial stack can include a textured portion disposed on a lower surface thereof.

[0090] The light emitting stack may additionally include an adhesion layer disposed between the first epitaxial stack and the second epitaxial stack.

[0091] The light emitting stack may additionally include a long pass filter disposed between the first epitaxial stack and the adhesion layer.

[0092] The first epitaxial stack can include an n-type semiconductor layer, an active layer disposed on the n-type semiconductor layer, a p-type semiconductor layer disposed on the active layer, and a first p-type contact electrode disposed on the p-type semiconductor layer.

[0093] The first p-type contact electrode may include a transparent conductive material.

[0094] The light emitting stack may additionally include a peripheral region disposed adjacent to the light emitting region in plan view, and the first p-type contact electrode is disposed to overlap the light emitting region.

[0095] The second epitaxial stack may include a second n-type semiconductor layer, an active layer of the second epitaxial stack disposed on the second n-type semiconductor layer, a p-type semiconductor layer of the second epitaxial stack disposed on the active layer of the second epitaxial stack, a second n-type contact electrode disposed on the second n-type semiconductor layer, and a second p-type contact electrode disposed on the p-type semiconductor layer of the second epitaxial stack.

[0096] The second p-type contact electrode may include a reflective material.

[0097] The electrode portion may include a common electrode connected to the first p-type contact electrode and the second p-type contact electrode, a first signal electrode connected to the n-type semiconductor layer of the first epitaxial stack, and a second signal electrode connected to the second n-type semiconductor layer.

[0098] A first contact hole may be provided through the second epitaxial stack, the active layer of the first epitaxial stack and the p-type semiconductor layer of the first epitaxial stack to expose an upper surface of the n-type semiconductor layer of the first epitaxial stack, and a first signal electrode is connected to the n-type semiconductor layer of the first epitaxial stack through the first contact hole.

[0099] A third contact hole may be provided through the second epitaxial stack to expose an upper surface of the first p-type contact electrode, and the common electrode is connected to the first p-type contact electrode through the third contact hole.

[0100] The light emitting stack structure may additionally include a first insulating layer covering the second epitaxial stack, and a second contact hole may be provided through the first insulating layer to expose the upper surface of the second n-type contact electrode, and the second signal electrode is connected to the second n-type contact electrode through the second contact hole.

[0101] The light-emitting stacked structure may additionally include a second insulating layer disposed on the first insulating layer, and a fourth contact hole may be provided through the second insulating layer to expose the upper surface of the second p-type contact electrode, and the common electrode is connected to the second p-type contact electrode through the fourth contact hole.

[0102] At least one of the n-type semiconductor layer and the second n-type semiconductor layer of the first epitaxial stack can include a textured portion disposed on a lower surface thereof.

[0103] The light emitting stack may additionally include a substrate disposed on a lower surface of the first epitaxial stack.

[0104] The light emitting stack may additionally include a light conversion layer disposed on the lower surface of the first epitaxial stack.

[0105] An embodiment of the inventive concept may provide a lighting device that includes a printed circuit board and a light emitting stack mounted on the printed circuit board.

[0106] One exemplary embodiment of the present disclosure provides a light-emitting diode stack for a display, the light-emitting diode stack including: a first LED stack including a first conductive type semiconductor layer and a second conductive type semiconductor layer; a second LED stack disposed on the first LED stack; a third LED stack disposed on the second LED stack; an ohmic electrode disposed on the opposite side of the second LED stack and forming ohmic contact with the first conductive type semiconductor layer of the first LED stack; and a reflective electrode disposed on the opposite side of the second LED stack and forming ohmic contact with the second conductive type semiconductor layer of the first LED stack, wherein light generated from the first LED stack is emitted to the outside via the second LED stack and the third LED stack, and light generated from the second LED stack is emitted to the outside via the third LED stack.

[0107] The structure in which the first to third LED stacks are stacked on top of each other allows the light-emitting diode stack to increase the light-emitting area of ​​each subpixel without increasing the pixel area. Light generated from the first LED stack is emitted to the outside through the second and third LED stacks, and light generated from the second LED stack is emitted to the outside through the third LED stack, thereby improving light-emitting efficiency.

[0108] The first LED stack can emit light having a longer wavelength than the second and third LED stacks, and the second LED stack can emit light having a longer wavelength than the third LED stack. For example, the first, second, and third LED stacks can emit red light, green light, and blue light, respectively. Because the first, second, and third LED stacks emit light having wavelengths that decrease in that order, optical interference between the LED stacks can be prevented.

[0109] The light emitting diode stack for a display may additionally include a first color filter interposed between the first LED stack and the second LED stack, which reflects light generated from the second LED stack while transmitting light generated from the first LED stack, and a second color filter interposed between the second LED stack and the third LED stack, which reflects light generated from the third LED stack while transmitting light generated from the first and second LED stacks. The first and second color filters enable the light emitting diode stack to prevent light generated from the second LED stack from entering the first LED stack and to prevent light generated from the third LED stack from entering the second LED stack, thereby further improving light emitting efficiency.

[0110] Each of the first and second color filters may be a low-pass filter, a band-pass filter, or a band-stop filter. In particular, each of the first and second color filters may include an insulating layer having a different refractive index. By including the insulating layer in the first and second color filters, the LED stack may have a stable structure and exhibit good light-emitting efficiency.

[0111] The light-emitting diode stack for a display may further include an interconnection line disposed below the first LED stack, insulated from the reflective electrode, and connected to the ohmic electrode. The interconnection line is electrically connected to the first conductivity type semiconductor layer of the first LED stack and can be used as a scan line or a data line in a display device.

[0112] The light emitting diode stack for a display may additionally include an insulating layer interposed between the reflective electrode and the interconnection line to insulate the interconnection line from the reflective electrode.

[0113] The light-emitting diode stack for a display may additionally include a support substrate, a first bonding layer interposed between the support substrate and the first LED stack, a second bonding layer interposed between the first LED stack and the second LED stack, and a third bonding layer interposed between the second LED stack and the third LED stack, wherein the second bonding layer transmits light generated from the first LED stack and the third bonding layer transmits light generated from the first and second LED stacks.

[0114] The first bonding layer may be adjacent to the interconnection line.

[0115] The light-emitting diode stack for a display may additionally include a second-p transparent electrode that forms ohmic contact with the p-type semiconductor layer of the second LED stack and a third-p transparent electrode that forms ohmic contact with the p-type semiconductor layer of the third LED stack. The light-emitting diode stack can achieve current spreading through the second-p transparent electrode and the third-p transparent electrode, which allow light generated from the corresponding LED stack to pass through, thereby preventing light loss.

[0116] In one exemplary embodiment, the light-emitting diode stack for a display may additionally include a first color filter interposed between the first LED stack and the second LED stack, which transmits light generated from the first LED stack while reflecting light generated from the second LED stack, and a second color filter interposed between the second LED stack and the third LED stack, which transmits light generated from the first and second LED stacks while reflecting light generated from the third LED stack, wherein the first color filter is disposed on the second bonding layer and the second color filter is disposed on the third bonding layer.

[0117] According to yet another exemplary embodiment of the present disclosure, there is provided a display device, the display device including a plurality of pixels arranged on a supporting substrate, each pixel including a first LED stack disposed on the supporting substrate and including a first conductive type semiconductor layer and a second conductive type semiconductor layer, a second LED stack disposed on the first LED stack, a third LED stack disposed on the second LED stack, an ohmic electrode interposed between the substrate and the first conductive type semiconductor layer of the first LED stack and forming an ohmic contact with the first conductive type semiconductor layer of the first LED stack, and a reflective electrode interposed between the substrate and the second conductive type semiconductor layer of the first LED stack and forming an ohmic contact with the second conductive type semiconductor layer of the first LED stack, wherein light generated from the first LED stack is emitted to the outside via the second LED stack and the third LED stack, and light generated from the second LED stack is emitted to the outside via the third LED stack.

[0118] The first LED stack can emit light having a longer wavelength than the second and third LED stacks, and the second LED stack can emit light having a longer wavelength than the third LED stack.

[0119] The display device may additionally include an interconnection line interposed between the supporting substrate and the first LED stack, insulated from the reflective electrode, and connected to the ohmic electrode.

[0120] The display device may additionally include an insulating layer interposed between the reflective electrode and the interconnection line to insulate the interconnection line from the reflective electrode.

[0121] The display device may additionally include a first color filter interposed between the first LED stack and the second LED stack, which transmits light generated from the first LED stack while reflecting light generated from the second LED stack, and a second color filter interposed between the second LED stack and the third LED stack, which transmits light generated from the first and second LED stacks while reflecting light generated from the third LED stack.

[0122] Each of the first color filter and the second color filter may be a low-pass filter, a band-pass filter, or a band-stop filter.

[0123] In each pixel, the p-type semiconductor layers of the first, second, and third LED stacks are electrically connected to a common line, and the n-type semiconductor layers thereof are electrically connected to different lines, and the interconnection line may be a line connected to the n-type semiconductor layer of the first LED stack.

[0124] The common line may be a data line and the different lines may be scan lines. Alternatively, the n-type semiconductor layers of the first, second, and third LED stacks may be electrically connected to a common line and the p-type semiconductor layers thereof may be electrically connected to different lines.

[0125] The reflective electrode is disposed continuously above a plurality of pixels to be used as a common line.

[0126] The display device may additionally include a lower insulating layer covering the side surfaces of the first, second, and third LED stacks, and the lower insulating layer may include openings exposing the reflective electrode, the second LED stack, and the third LED stack.

[0127] The lower insulating layer may include distributed Bragg reflectors that reflect red, green, and blue light.

[0128] According to one exemplary embodiment of the present disclosure, a light-emitting diode pixel for a display includes a first LED stack, a second LED stack disposed within a partial area on the first LED stack, a third LED stack disposed within a partial area on the second LED stack, and a reflective electrode disposed below the first LED stack, wherein each of the first to third LED stacks includes an n-type semiconductor layer and a p-type semiconductor layer, and all of the n-type semiconductor layers of the first to third LED stacks are electrically connected to the reflective electrode, and the first LED stack, the second LED stack, and the third LED stack are independently driven.

[0129] Due to the structure in which the first to third LED stacks can be arranged on top of each other, the first to third LED stacks can be manufactured at the wafer level by wafer bonding, thereby eliminating the need for individual packaging of the first to third LED stacks.

[0130] In addition, since the second LED stack is disposed within a partial area on the first LED stack and the third LED stack is disposed within a partial area on the second LED stack, the light-emitting diode pixel can reduce light loss induced by absorption of light emitted from the first LED stack and the second LED stack by the second LED stack or the third LED stack.

[0131] In addition, since the n-type semiconductor layers of the first to third LED stacks are electrically connected to the reflective electrode, it is possible to provide a pixel in which the cathodes of the first to third LED stacks are electrically connected to a common line.

[0132] The first, second, and third LED stacks emit light having different wavelengths. In some exemplary embodiments, the first LED stack can emit light having a longer wavelength than the second LED stack, and the second LED stack can emit light having a longer wavelength than the third LED stack. For example, the first, second, and third LED stacks can emit red, green, and blue light, respectively.

[0133] The p-type semiconductor layers of the first to third LED stacks are disposed on the n-type semiconductor layer thereof, respectively, and the reflective electrode can form ohmic contact with the n-type semiconductor layer of the first LED stack.

[0134] The light-emitting diode pixel may additionally include a first color filter interposed between the first LED stack and the second LED stack and a second color filter interposed between the second LED stack and the third LED stack, wherein the first color filter can transmit light generated from the first LED stack while reflecting light generated from the second LED stack, and the second color filter can transmit light generated from the second LED stack while reflecting light generated from the third LED stack.

[0135] The first color filter may be adjacent to the n-type semiconductor layer of the second LED stack, and the second color filter may be adjacent to the n-type semiconductor layer of the third LED stack.

[0136] The light-emitting diode pixel may additionally include a second bonding layer interposed between the first LED stack and the first color filter, and a third bonding layer interposed between the second LED stack and the second color filter, wherein the second bonding layer is capable of transmitting light generated from the first LED stack, and the third bonding layer is capable of transmitting light generated from the second LED stack.

[0137] The light-emitting diode pixel may additionally include a 1-2 ohmic electrode in contact with the p-type semiconductor layer of the first LED stack, a 2-1 ohmic electrode in contact with the n-type semiconductor layer of the second LED stack, a 2-2 ohmic electrode in contact with the p-type semiconductor layer of the second LED stack, a 3-1 ohmic electrode in contact with the n-type semiconductor layer of the third LED stack, and a 3-2 ohmic electrode in contact with the p-type semiconductor layer of the third LED stack. In addition, the 1-2 ohmic electrode can be in contact with the n-type semiconductor layer outside a partial region of the first LED stack, and the 2-1 ohmic electrode and the 2-2 ohmic electrode can be in contact with the n-type and p-type semiconductor layers, respectively, outside a partial region of the second LED stack.

[0138] Furthermore, the 3-1 ohmic electrode can be in contact with the n-type semiconductor layer on the n-type semiconductor layer of the third LED stack, and the 3-2 ohmic electrode can be in contact with the p-type semiconductor layer on the p-type semiconductor layer of the third LED stack.

[0139] The light-emitting diode pixel may further include connecting portions that electrically connect the second-first ohmic electrode and the third-first ohmic electrode to the reflective electrode, respectively, so that the n-type semiconductor layer of the second LED stack and the p-type semiconductor layer of the third LED stack are electrically connected to the reflective electrode via the ohmic electrodes and the connecting portions.

[0140] Meanwhile, the area of ​​the first LED stack region excluding a portion of the first LED stack, the area of ​​the second LED stack region excluding a portion of the second LED stack, and the area of ​​the third LED stack region may be different from one another. Since the first to third LED stacks emit light having different visibility from one another, by adjusting the areas of the first to third LED stacks, it is possible to increase the luminous intensity of light having lower visibility to be greater than the luminous intensity of light having higher visibility.

[0141] According to yet another exemplary embodiment of the present disclosure, there is provided a display device, the display device including a plurality of pixels arranged on a support substrate, each pixel including a first LED stack, a second LED stack disposed within a partial region on the first LED stack, a third LED stack disposed within a partial region on the second LED stack, and a reflective electrode disposed below the first LED stack, each of the first to third LED stacks including an n-type semiconductor layer and a p-type semiconductor layer, all of the n-type semiconductor layers of the first to third LED stacks being electrically connected to the reflective electrode, and the first LED stack, the second LED stack, and the third LED stack being independently drivable.

[0142] The first LED stack, the second LED stack, and the third LED stack can emit light having wavelengths different from each other.

[0143] The n-type semiconductor layer of the first LED stack, the n-type semiconductor layer of the second LED stack, and the n-type semiconductor layer of the third LED stack are electrically connected to a common line, and the p-type semiconductor layer of the first LED stack, the p-type semiconductor layer of the second LED stack, and the p-type semiconductor layer of the third LED stack are electrically connected to different lines, so that the first LED stack, the second LED stack, and the third LED stack can be driven independently.

[0144] Meanwhile, the p-type semiconductor layers of the first to third LED stacks are disposed on the n-type semiconductor layers thereof, respectively, and the reflective electrode can form ohmic contact with the n-type semiconductor layer of the first LED stack.

[0145] Each pixel may additionally include a first color filter interposed between the first LED stack and the second LED stack and a second color filter interposed between the second LED stack and the third LED stack, the first color filter transmitting light generated from the first LED stack while reflecting light generated from the second LED stack, and the second color filter transmitting light generated from the second LED stack while reflecting light generated from the third LED stack.

[0146] Each pixel may additionally include a first bonding layer interposed between the support substrate and the reflective electrode, a second bonding layer interposed between the first LED stack and the first color filter, and a third bonding layer interposed between the second LED stack and the second color filter.

[0147] Each pixel may additionally include a 1-2 ohmic electrode in contact with the p-type semiconductor layer of the first LED stack, a 2-1 ohmic electrode in contact with the n-type semiconductor layer of the second LED stack, a 2-2 ohmic electrode in contact with the p-type semiconductor layer of the second LED stack, a 3-1 ohmic electrode in contact with the n-type semiconductor layer of the third LED stack, and a 3-2 ohmic electrode in contact with the p-type semiconductor layer of the third LED stack. In addition, the 1-2 ohmic electrode can be in contact with the p-type semiconductor layer outside a partial region of the first LED stack, and the 2-1 ohmic electrode and the 2-2 ohmic electrode can be in contact with the n-type and p-type semiconductor layers, respectively, outside a partial region of the second LED stack.

[0148] Furthermore, the 3-1 ohmic electrode can be in contact with the n-type semiconductor layer on the n-type semiconductor layer of the third LED stack, and the 3-2 ohmic electrode can be in contact with the p-type semiconductor layer on the p-type semiconductor layer of the third LED stack.

[0149] Each pixel may additionally include a connection portion electrically connecting the second-first ohmic electrode and the third-first ohmic electrode to the reflective electrode, respectively.

[0150] Meanwhile, the area of ​​the first LED stack region excluding a portion of the first LED stack, the area of ​​the second LED stack region excluding a portion of the second LED stack, and the area of ​​the third LED stack region may be different from each other. For example, the area of ​​the first LED stack region excluding a portion of the first LED stack may be larger than the area of ​​the second LED stack region excluding a portion of the second LED stack, and the areas of the third LED stack regions may be different from each other.

[0151] According to one exemplary embodiment of the present disclosure, a light emitting diode stack for a display includes a support substrate, a 1-1 LED stack disposed on the support substrate, a 1-2 LED stack disposed on the 1-1 LED stack, a second LED stack disposed on the 1-2 LED stack, and a third LED stack disposed on the second LED stack, wherein the 1-1 LED stack and the 1-2 LED stack are adapted to emit red light, the second LED stack is adapted to emit green light, and the third LED stack is adapted to emit blue light.

[0152] The structure in which the first to third LED stacks are stacked on top of each other allows the light-emitting diode stack to increase the light-emitting area of ​​each subpixel without increasing the pixel area. Also, the structure in which the first-first LED stack is arranged to overlap the first-second LED stack allows the light-emitting diode stack to increase the brightness of red light without increasing the area occupied by it in a two-dimensional plane.

[0153] In one exemplary embodiment, the light-emitting diode stack may further include a first upper ohmic contact layer that forms ohmic contact with the upper surface of the first LED stack and a second lower ohmic contact layer that forms ohmic contact with the lower surface of the second LED stack, and the first upper ohmic contact layer and the first lower ohmic contact layer are electrically connected to each other.

[0154] The light-emitting diode stack may additionally include a 1-1 lower ohmic contact layer that forms ohmic contact with the lower surface of the 1-1 LED stack and a 1-2 upper ohmic contact layer that forms ohmic contact with the upper surface of the 1-2 LED stack, and the 1-1 LED stack and the 1-2 LED stack are connected to each other in series between the 1-1 lower ohmic contact layer and the 1-2 upper ohmic contact layer.

[0155] The first-1 lower ohmic contact layer may include a reflective layer that reflects light generated from the first-1 LED stack, thereby improving the luminous efficiency of the first-1 LED stack.

[0156] The light-emitting diode stack may further include a second bonding layer interposed between the first LED stack and the first second LED stack. The second bonding layer may be a transparent conductive layer. By using the transparent conductive layer as the bonding layer, the first LED stack and the first second LED stack can be easily electrically connected to each other.

[0157] In some example embodiments, the light-emitting diode stack may further include a first upper ohmic contact layer that forms ohmic contact with the upper surface of the first LED stack, a first lower ohmic contact layer that forms ohmic contact with the lower surface of the second LED stack, and a second bonding layer interposed between the first LED stack and the first LED stack, wherein the first upper ohmic contact layer is insulated from the first lower ohmic contact layer by the second bonding layer, and the second bonding layer is formed of an insulating material.

[0158] The light-emitting diode stack may further include a 1-1 lower ohmic contact layer that forms ohmic contact with the lower surface of the 1-1 LED stack and a 1-2 upper ohmic contact layer that forms ohmic contact with the upper surface of the 1-2 LED stack, where the 1-1 lower ohmic contact layer is electrically connected to the 1-2 lower ohmic contact layer and the 1-2 upper ohmic contact layer is electrically connected to the 1-1 upper ohmic contact layer. Thus, the 1-1 LED stack is connected in parallel to the 1-2 LED stack.

[0159] The light-emitting diode stack may additionally include a first color filter interposed between the 1-2 LED stack and the 2nd LED stack, which reflects light generated from the 2nd LED stack while transmitting light generated from the 1-1 and 1-2 LED stacks, and a second color filter interposed between the 2nd LED stack and the 3rd LED stack, which reflects light generated from the 3rd LED stack while transmitting light generated from the 1-1, 1-2 and 2nd LED stacks.

[0160] Light generated from the 1-1 and 1-2 LED stacks is emitted to the outside via the second LED stack and the third LED stack, and light generated from the second LED stack is emitted to the outside via the third LED stack.

[0161] The first and second color filters enable the light-emitting diode stack to prevent light generated from the second LED stack from entering the first-second LED stack, and to prevent light generated from the third LED stack from entering the second LED stack, thereby reducing light loss.

[0162] In another exemplary embodiment, the second LED stack is disposed within a partial area above the first-second LED stack, and the third LED stack is disposed within a partial area above the second LED stack, so that some light generated from the first-first and first-second LED stacks is emitted to the outside without passing through the second LED stack, and some light generated from the second LED stack is emitted to the outside without passing through the third LED stack.

[0163] The light-emitting diode stack may additionally include a support substrate disposed below the 1-1 LED stack, a first bonding layer interposed between the support substrate and the 1-1 LED stack, a third bonding layer interposed between the 1-2 LED stack and the first color filter, and a fourth bonding layer interposed between the second LED stack and the second color filter, wherein the third bonding layer transmits light generated from the 1-1 and 1-2 LED stacks, and the fourth bonding layer transmits light generated from the 1-1, 1-2, and 2 LED stacks.

[0164] The light-emitting diode stack may additionally include a second transparent electrode interposed between the first color filter and the second LED stack and forming an ohmic contact with the second LED stack, and a third transparent electrode interposed between the second color filter and the third LED stack and forming an ohmic contact with the third LED stack.

[0165] The second and third transparent electrodes can aid in current spreading in the second and third LED stacks.

[0166] According to another exemplary embodiment of the present disclosure, a display device includes a plurality of pixels arranged on a support substrate, each pixel including a 1-1 LED stack disposed on the support substrate, a 1-2 LED stack disposed on the 1-1 LED stack, a second LED stack disposed on the 1-2 LED stack, and a third LED stack disposed on the second LED stack, wherein the 1-1 LED stack and the 1-2 LED stack are adapted to emit red light, the second LED stack is adapted to emit green light, and the third LED stack is adapted to emit blue light.

[0167] Each pixel is adapted to emit red light using overlapping 1-1 LED stacks and 1-2 LED stacks, thereby increasing the brightness of the red light within each pixel without increasing the area of ​​the subpixel.

[0168] In one exemplary embodiment, the 1-1 LED stack and the 1-2 LED stack are connected in series, and in each pixel, the p-type semiconductor layers of the 1-1, 2, and 3 LED stacks are electrically connected to a common line, and the n-type semiconductor layers of the 1-2, 2, and 3 LED stacks are electrically connected to different lines.

[0169] In another exemplary embodiment, the 1-1 LED stack and the 1-2 LED stack are connected in parallel to each other, and in each pixel, the p-type semiconductor layers of the 1-1, 1-2, 2nd, and 3rd LED stacks are electrically connected to a common line, the n-type semiconductor layers of the 1-1, 2nd, and 3rd LED stacks are electrically connected to different lines, and the n-type semiconductor layer of the 1-2 LED stack is electrically connected to the n-type semiconductor layer of the 1-1 LED stack.

[0170] The display device may additionally include a lower insulating layer covering the side surfaces of the 1-1, 1-2, 2nd and 3rd LED stacks, and the lower insulating layer may include openings exposing at least a portion of the 1-2, 2nd and 3rd LED stacks.

[0171] The display device may further include a reflective electrode interposed between the support substrate and the first LED stack, the reflective electrode being continuously disposed over the plurality of pixels.

[0172] The display device may additionally include a first color filter interposed between the 1-2 LED stack and the 2nd LED stack, which reflects light generated from the 2nd LED stack while transmitting light generated from the 1-1 and 1-2 LED stacks, and a second color filter interposed between the 2nd LED stack and the 3rd LED stack, which reflects light generated from the 3rd LED stack while transmitting light generated from the 1-1, 1-2 and 2nd LED stacks.

[0173] Light generated from the 1-1 and 1-2 LED stacks is emitted to the outside via the second LED stack and the third LED stack, and light generated from the second LED stack is emitted to the outside via the third LED stack.

[0174] In another exemplary embodiment, the second LED stack is disposed within a partial area above the first-second LED stack, and the third LED stack is disposed within a partial area above the second LED stack, so that some light generated from the first-first and first-second LED stacks is emitted to the outside without passing through the second LED stack, and some light generated from the second LED stack is emitted to the outside without passing through the third LED stack.

[0175] In each pixel, the second and third LED stacks are drivable independently of the first-1 and first-2 LED stacks, and the first-1 and first-2 LED stacks are drivable together.

[0176] According to one exemplary embodiment of the present disclosure, there is provided a light emitting diode stack for a display, the light emitting diode stack including a first LED stack, a second LED stack disposed on the first LED stack, and a third LED stack disposed on the second LED stack, wherein the first LED stack has a multi-junction LED stack structure.

[0177] The structure in which the first to third LED stacks are stacked on top of each other allows the light-emitting diode stack to increase the light-emitting area of ​​each subpixel without increasing the pixel area. Also, by employing the first LED stack having a multi-junction LED stack structure, the light-emitting diode stack can increase the brightness of the first LED stack without increasing the light-emitting area and current density.

[0178] Here, the term "LED stack" refers to a stack of semiconductor layers capable of emitting light. Additionally, a multi-junction LED stack structure refers to an LED stack formed by the tunnel junction of two or more LED stacks.

[0179] The first LED stack may include a 1-1 LED stack, a 1-2 LED stack, and a tunnel junction layer interposed between the 1-1 LED stack and the 1-2 LED stack, and each of the 1-1 LED stack and the 1-2 LED stack includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer.

[0180] The first LED stack can include an AlGaInP-based semiconductor layer.

[0181] The first LED stack can emit red light having a longer wavelength than the second and third LED stacks, and the second LED stack can emit red light having a longer wavelength than the third LED stack. The first-first LED stack can emit light having the same or similar wavelength as the first-second LED stack. For example, the first, second, and third LED stacks can emit red, green, and blue light, respectively.

[0182] Furthermore, light generated from the first LED stack is emitted to the outside via the second LED stack and the third LED stack, and light generated from the second LED stack is emitted to the outside via the third LED stack.

[0183] In another exemplary embodiment, the second LED stack is disposed within a partial area on the first LED stack, and the third LED stack is also disposed within a partial area on the second LED stack, so that at least a portion of the light generated from the first LED stack is emitted to the outside without passing through the second LED stack, and at least a portion of the light generated from the second LED stack is emitted to the outside without passing through the third LED stack.

[0184] The light-emitting diode stack may additionally include a first color filter interposed between the first LED stack and the second LED stack, which transmits light generated from the first LED stack while reflecting light generated from the second LED stack, and a second color filter interposed between the second LED stack and the third LED stack, which transmits light generated from the first and second LED stacks while reflecting light generated from the third LED stack.

[0185] The first and second color filters allow the light generated from the first LED stack to be emitted to the outside through the second LED stack and the third LED stack, allow the light generated from the second LED stack to be emitted to the outside through the third LED stack, prevent the light generated from the second LED stack from entering the first LED stack, and prevent the light generated from the third LED stack from entering the second LED stack, thereby improving the light-emitting efficiency.

[0186] Each of the first and second color filters may be a low-pass filter, a band-pass filter, or a band-stop filter. In particular, each of the first and second color filters may include a distributed Bragg reflector. By including the distributed Bragg reflector in the first and second color filters, the LED stack may have a stable structure and exhibit good light-emitting efficiency.

[0187] The light-emitting diode stack may additionally include a second bonding layer interposed between the first LED stack and the first color filter, and a third bonding layer interposed between the second LED stack and the second color filter, wherein the second bonding layer transmits light generated from the first LED stack, and the third bonding layer transmits light generated from the first LED stack and the second LED stack.

[0188] The second and third bonding layers allow the first LED stack, the second LED stack and the third LED stack to be bonded to each other while allowing light to be emitted to the outside through the second and third bonding layers, thereby preventing light loss.

[0189] The light emitting diode stack may additionally include a support substrate disposed below the first LED stack, and a first bonding layer interposed between the support substrate and the first LED stack.

[0190] The light emitting diode stack may additionally include a first reflective electrode interposed between the first bonding layer and the first LED stack and forming an ohmic contact with the p-type semiconductor layer of the first LED stack.

[0191] The first reflective electrode can reflect light generated from the first LED stack to improve the light emitting efficiency of the first LED stack.

[0192] The light emitting diode stack may additionally include a first ohmic electrode forming an ohmic contact with the top surface of the first LED stack.

[0193] The light-emitting diode stack may additionally include a second transparent electrode interposed between the first color filter and the second LED stack and forming an ohmic contact with the p-type semiconductor layer of the second LED stack, and a third transparent electrode interposed between the second color filter and the third LED stack and forming an ohmic contact with the p-type semiconductor layer of the third LED stack, wherein light generated from the first LED stack is emitted to the outside through the second transparent electrode and the third transparent electrode, and light generated from the second LED stack is emitted to the outside through the third transparent electrode.

[0194] According to yet another exemplary embodiment of the present disclosure, there is provided a display device, the display device including a plurality of pixels arranged on a support substrate, each pixel including a first LED stack disposed on the support substrate, a second LED stack disposed on the first LED stack, and a third LED stack disposed on the second LED stack, the first LED stack having a multi-junction LED stack structure.

[0195] The multi-junction LED stack structure allows the first LED stack to have improved brightness.

[0196] The first LED stack may include a 1-1 LED stack, a 1-2 LED stack, and a tunnel junction layer interposed between the 1-1 LED stack and the 1-2 LED stack, and each of the 1-1 LED stack and the 1-2 LED stack includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer.

[0197] The first LED stack can include an AlGaInP-based semiconductor layer.

[0198] The display device may additionally include a first color filter interposed between the first LED stack and the second LED stack, which reflects light generated from the second LED stack while transmitting light generated from the first LED stack, and a second color filter interposed between the second LED stack and the third LED stack, which reflects light generated from the third LED stack while transmitting light generated from the first and second LED stacks, wherein the light generated from the first LED stack is emitted to the outside via the second LED stack and the third LED stack, and the light generated from the second LED stack is emitted to the outside via the third LED stack.

[0199] Each of the first and second color filters may be a low-pass filter, a band-pass filter, or a band-stop filter, and may include a distributed Bragg reflector having high reflectivity in a specific wavelength band.

[0200] In another exemplary embodiment, the second LED stack is disposed within a partial area on the first LED stack, and the third LED stack is also disposed within a partial area on the second LED stack, so that at least a portion of the light generated from the first LED stack is emitted to the outside without passing through the second LED stack, and at least a portion of the light generated from the second LED stack is emitted to the outside without passing through the third LED stack.

[0201] In each pixel, the p-type semiconductor layers of the first, second, and third LED stacks are electrically connected to a common line, and the n-type semiconductor layers are electrically connected to different lines, for example, the common line may be a data line, and the different lines may be scan lines.

[0202] The display device may additionally include a lower insulating layer covering the side surfaces of the first to third LED stacks, and the lower insulating layer may include distributed Bragg reflectors that reflect red, green, and blue light.

[0203] In one exemplary embodiment, the display device may additionally include a reflective electrode interposed between the first LED stack and the supporting substrate.

[0204] The reflective electrode is disposed continuously above a plurality of pixels to be used as a common line.

[0205] In another exemplary embodiment, the display device may further include reflective electrodes interposed between the support substrate and the first LED stack, and each reflective electrode may be confined within each pixel area.

[0206] In each pixel, the first to third LED stacks can be driven independently.

[0207] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. [Effects of the Invention]

[0208] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display, and a display device having the same, that allows an increase in the light-emitting area of ​​each sub-pixel without increasing the pixel area.

[0209] Exemplary embodiments of the present disclosure provide a display light emitting diode and a display device having the same that do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0210] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display, and a display device having the same, that allows an increase in the light-emitting area of ​​each sub-pixel without increasing the pixel area.

[0211] Exemplary embodiments of the present disclosure provide a display light emitting diode and a display device having the same that do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0212] Exemplary embodiments of the present disclosure provide light emitting diode pixels for displays, and display devices including the same, that do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0213] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display that allows an increase in the light-emitting area of ​​each sub-pixel without increasing the pixel area, and a display device including the same.

[0214] Exemplary embodiments of the present disclosure provide a display light emitting diode and a display device including the same, which do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0215] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light emitting diode for a display, and a display device including the same, capable of adjusting light emission in consideration of visibility.

[0216] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display, and a display device having the same, that allows an increase in the light-emitting area of ​​each sub-pixel without increasing the pixel area.

[0217] Exemplary embodiments of the present disclosure provide a display light emitting diode and a display device having the same that do not need to be individually mounted on a display panel by allowing multiple pixels to be fabricated simultaneously.

[0218] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure provide a light-emitting diode for a display, and a display device having the same, capable of adjusting light emission in consideration of visibility. [Brief explanation of the drawings]

[0219] [Figure 1] 1 is a schematic cross-sectional view of a light-emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 2] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 3] FIG. 2 is a schematic circuit diagram illustrating the operation of a display device according to one exemplary embodiment of the present disclosure. [Figure 4] 1 is a schematic plan view of a display device according to an exemplary embodiment of the present disclosure. [Figure 5] 5 is an enlarged plan view of one pixel of the display device shown in FIG. 4. [Figure 6] FIG. 6 is a schematic cross-sectional view taken along line AA in FIG. 5. [Figure 7] FIG. 6 is a schematic cross-sectional view taken along line BB in FIG. 5. [Figure 8A] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8B] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8C] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8D] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8E] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8F] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8G] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8H] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8I] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8J] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 8K] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 9] FIG. 10 is a schematic circuit diagram illustrating the operation of a display device according to another exemplary embodiment of the present disclosure. [Figure 10] FIG. 10 is a schematic plan view of a display device according to another exemplary embodiment of the present disclosure. [Figure 11] FIG. 2 is a schematic cross-sectional view of a light-emitting diode stack for a display according to another exemplary embodiment of the present disclosure. [Figure 12A] 5A-5C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting diode stack for a display according to yet another exemplary embodiment of the present disclosure. [Figure 12B] 5A-5C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting diode stack for a display according to yet another exemplary embodiment of the present disclosure. [Figure 12C] 5A-5C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting diode stack for a display according to yet another exemplary embodiment of the present disclosure. [Figure 12D]5A-5C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting diode stack for a display according to yet another exemplary embodiment of the present disclosure. [Figure 12E] 5A-5C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting diode stack for a display according to yet another exemplary embodiment of the present disclosure. [Figure 12F] 5A-5C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting diode stack for a display according to yet another exemplary embodiment of the present disclosure. [Figure 13] 1 is a schematic cross-sectional view of a light-emitting diode stack for a display according to another exemplary embodiment of the present disclosure. [Figure 14] 1 is a schematic cross-sectional view of a light-emitting diode stack for a display according to yet another exemplary embodiment of the present disclosure. [Figure 15] 1 is a cross-sectional view illustrating a light-emitting stack structure according to an exemplary embodiment of the present disclosure. [Figure 16] 1 is a cross-sectional view illustrating a light-emitting stack structure having line contact portions according to an exemplary embodiment of the present disclosure. [Figure 17A] 17A and 17B are cross-sectional views showing in detail each epitaxial stack of FIG. 16. [Figure 17B] 17A and 17B are cross-sectional views showing in detail each epitaxial stack of FIG. 16. [Figure 17C] 17A and 17B are cross-sectional views showing in detail each epitaxial stack of FIG. 16. [Figure 18] 1 is a cross-sectional view illustrating a light-emitting stack having a predetermined pass filter according to an exemplary embodiment of the present disclosure. [Figure 19] 1A and 1B are cross-sectional views illustrating light emitting stack structures having textured portions formed in at least a portion of the epitaxial stack according to exemplary embodiments of the present disclosure. [Figure 20] 1A and 1B are cross-sectional views illustrating light emitting stack structures having textured portions formed in at least a portion of the epitaxial stack according to exemplary embodiments of the present disclosure. [Figure 21] FIG. 1 is a plan view illustrating a display device according to an exemplary embodiment of the present disclosure. [Figure 22]FIG. 22 is an enlarged plan view showing a portion P1 of FIG. 21. [Figure 23] FIG. 1 is a block diagram illustrating a display device according to an exemplary embodiment of the present disclosure. [Figure 24] FIG. 1 is a circuit diagram illustrating one sub-pixel for a passive matrix type display device. [Figure 25] FIG. 1 is a circuit diagram showing a first sub-pixel for an active matrix type display device. [Figure 26] FIG. 2 is a plan view illustrating a pixel according to an exemplary embodiment of the present disclosure. [Figure 27A] FIG. 27 is a cross-sectional view taken along line II' in FIG. 26. [Figure 27B] FIG. 27 is a cross-sectional view taken along line II-II' in FIG. 26. [Figure 28] FIG. 2 is a plan view showing a substrate on which first to third epitaxial stacks are laminated. [Figure 29A] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29B] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29C] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29D] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29E] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29F] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29G] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29H] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29I] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29J] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29K] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 29L] 29 is a cross-sectional view taken along line II' of FIG. 28, showing the steps of laminating first to third epitaxial stacks on a substrate in order. [Figure 30A] 10A to 10C are plan views sequentially showing steps of connecting the second and third epitaxial stacks to the second and third sub-scan lines and the data lines. [Figure 30B] 30B are cross-sectional views taken along lines II', IIa-IIa', and IIb-IIb' in FIG. 30A. [Figure 31A] 10A to 10C are plan views sequentially showing steps of connecting the second and third epitaxial stacks to the second and third sub-scan lines and the data lines. [Figure 31B] 31B are cross-sectional views taken along lines II', IIa-IIa', and IIb-IIb' in FIG. 31A. [Figure 32A] 10A to 10C are plan views sequentially showing steps of connecting the second and third epitaxial stacks to the second and third sub-scan lines and the data lines. [Figure 32B] 32B are cross-sectional views taken along lines II', IIa-IIa', and IIb-IIb' in FIG. 32A. [Figure 33A] 10A to 10C are plan views sequentially showing steps of connecting the second and third epitaxial stacks to the second and third sub-scan lines and the data lines. [Figure 33B]33B are cross-sectional views taken along lines II', IIa-IIa', and IIb-IIb' in FIG. 33A. [Figure 34A] 10A to 10C are plan views sequentially showing steps of connecting the second and third epitaxial stacks to the second and third sub-scan lines and the data lines. [Figure 34B] 34B are cross-sectional views taken along lines II', IIa-IIa', and IIb-IIb' in FIG. 34A. [Figure 35A] 10A to 10C are plan views sequentially showing steps of connecting the second and third epitaxial stacks to the second and third sub-scan lines and the data lines. [Figure 35B] 35B are cross-sectional views taken along lines II', IIa-IIa', and IIb-IIb' in FIG. 35A. [Figure 36A] 1 is a cross-sectional view illustrating a light-emitting stack structure according to an exemplary embodiment of the present disclosure. [Figure 36B] 1 is a cross-sectional view illustrating a light-emitting stack structure according to an exemplary embodiment of the present disclosure. [Figure 36C] 1 is a cross-sectional view illustrating a light-emitting stack structure according to an exemplary embodiment of the present disclosure. [Figure 37A] FIG. 1 is a plan view illustrating a light-emitting stack structure according to an exemplary embodiment of the present disclosure. [Figure 37B] FIG. 37B is a cross-sectional view taken along line II' of FIG. 37A. [Figure 38A] 1A to 1C are plan views sequentially illustrating a method for manufacturing a light-emitting stacked structure according to an exemplary embodiment of the present disclosure. [Figure 38B] FIG. 38B is a cross-sectional view taken along line II in FIG. 38A. [Figure 39A] 1A to 1C are plan views sequentially illustrating a method for manufacturing a light-emitting stacked structure according to an exemplary embodiment of the present disclosure. [Figure 39B] FIG. 39B is a cross-sectional view taken along line II in FIG. 39A. [Figure 40A] 1A to 1C are plan views sequentially illustrating a method for manufacturing a light-emitting stacked structure according to an exemplary embodiment of the present disclosure. [Figure 40B] FIG. 40B is a cross-sectional view taken along line II in FIG. 40A. [Figure 40C] FIG. 40B is a cross-sectional view taken along line II in FIG. 40A. [Figure 40D] FIG. 40B is a cross-sectional view taken along line II in FIG. 40A. [Figure 40E] FIG. 40B is a cross-sectional view taken along line II in FIG. 40A. [Figure 40F] FIG. 40B is a cross-sectional view taken along line II in FIG. 40A. [Figure 40G] FIG. 40B is a cross-sectional view taken along line II in FIG. 40A. [Figure 41A] 1A to 1C are plan views sequentially illustrating a method for manufacturing a light-emitting stacked structure according to an exemplary embodiment of the present disclosure. [Figure 41B] FIG. 41B is a cross-sectional view taken along line II in FIG. 41A. [Figure 41C] FIG. 41B is a cross-sectional view taken along line II in FIG. 41A. [Figure 41D] FIG. 41B is a cross-sectional view taken along line II in FIG. 41A. [Figure 42A] 1A to 1C are plan views sequentially illustrating a method for manufacturing a light-emitting stacked structure according to an exemplary embodiment of the present disclosure. [Figure 42B] FIG. 42B is a cross-sectional view taken along line II in FIG. 42A. [Figure 43A] 1A to 1C are plan views sequentially illustrating a method for manufacturing a light-emitting stacked structure according to an exemplary embodiment of the present disclosure. [Figure 43B] FIG. 43B is a cross-sectional view taken along line II in FIG. 43A. [Figure 44] 1 is a cross-sectional view illustrating a light-emitting stack structure according to an exemplary embodiment of the present disclosure. [Figure 45] FIG. 2 is a cross-sectional view showing a textured portion formed on a second epitaxial stack. [Figure 46] 1 is a cross-sectional view illustrating a light-emitting stack structure according to an exemplary embodiment of the present disclosure. [Figure 47] 1 is a cross-sectional view illustrating a light-emitting stack structure having a light conversion layer according to an exemplary embodiment of the present disclosure. [Figure 48] 1 is a cross-sectional view illustrating a light-emitting stack structure having a light conversion layer according to an exemplary embodiment of the present disclosure. [Figure 49] FIG. 2 is a plan view illustrating a light emitting stack structure mounted on a printed circuit board according to an exemplary embodiment of the present disclosure. [Figure 50]FIG. 2 is a plan view illustrating a light emitting stack structure mounted on a printed circuit board according to an exemplary embodiment of the present disclosure. [Figure 51] 1 is a schematic cross-sectional view of a light-emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 52A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 52B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 52C] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 52D] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 52E] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 53] FIG. 2 is a schematic circuit diagram illustrating the operation of a display device according to one exemplary embodiment of the present disclosure. [Figure 54] 1 is a schematic plan view of a display device according to an exemplary embodiment of the present disclosure. [Figure 55] FIG. 55 is an enlarged plan view of one pixel of the display device shown in FIG. 54. [Figure 56] FIG. 56 is a schematic cross-sectional view taken along line AA in FIG. 55. [Figure 57] FIG. 56 is a schematic cross-sectional view taken along line BB in FIG. 55. [Figure 58A] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 58B] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 58C] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 58D] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 58E] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 58F] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 58G] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 58H] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 59] FIG. 10 is a schematic plan view of a display device according to another exemplary embodiment of the present disclosure. [Figure 60] 1 is a schematic cross-sectional view of a light-emitting diode pixel for a display according to one exemplary embodiment of the present disclosure. [Figure 61] FIG. 2 is a schematic circuit diagram illustrating the operation of a display device according to an exemplary embodiment of the present disclosure. [Figure 62] 1 is a schematic plan view of a display device according to a specific illustrative embodiment of the present disclosure; [Figure 63] FIG. 63 is an enlarged plan view of one pixel of the display device shown in FIG. 62. [Figure 64A] FIG. 64 is a schematic cross-sectional view taken along line AA in FIG. 63. [Figure 64B] FIG. 64 is a schematic cross-sectional view taken along line BB in FIG. 63. [Figure 64C] FIG. 64 is a schematic cross-sectional view taken along line CC in FIG. 63. [Figure 64D] FIG. 64 is a schematic cross-sectional view taken along line DD in FIG. 63. [Figure 65A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 65B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 66A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 66B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 67A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 67B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 67C] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 68A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 68B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 68C] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 69A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 69B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 70A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 70B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 71A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 71B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 72A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 72B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 73A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 73B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 74A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 74B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 75] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 76A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 76B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 77] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a display device according to certain exemplary embodiments of the present disclosure. [Figure 78] FIG. 10 is a schematic circuit diagram illustrating the operation of a display device according to another exemplary embodiment of the present disclosure. [Figure 79] 1 is a schematic cross-sectional view of a light-emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 80] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 81] FIG. 2 is a schematic circuit diagram illustrating the operation of a display device according to one exemplary embodiment of the present disclosure. [Figure 82]1 is a schematic plan view of a display device according to an exemplary embodiment of the present disclosure. [Figure 83] FIG. 83 is an enlarged plan view of one pixel of the display device shown in FIG. 82. [Figure 84] FIG. 84 is a schematic cross-sectional view taken along line AA in FIG. 83. [Figure 85] FIG. 84 is a schematic cross-sectional view taken along line BB in FIG. 83. [Figure 86A] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86B] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86C] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86D] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86E] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86F] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86G] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86H] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86I] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86J] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 86K] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 87]FIG. 10 is a schematic plan view of a display device according to another exemplary embodiment of the present disclosure. [Figure 88] FIG. 10 is a schematic circuit diagram illustrating the operation of a display device according to another exemplary embodiment of the present disclosure. [Figure 89A] 1 is a schematic cross-sectional view of a light-emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 89B] FIG. 89B is an enlarged cross-sectional view of the first LED stack of FIG. 89A. [Figure 90A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 90B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 90C] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure. [Figure 91] FIG. 2 is a schematic circuit diagram illustrating the operation of a display device according to one exemplary embodiment of the present disclosure. [Figure 92] 1 is a schematic plan view of a display device according to an exemplary embodiment of the present disclosure. [Figure 93] FIG. 93 is an enlarged plan view of one pixel of the display device shown in FIG. 92. [Figure 94] FIG. 94 is a schematic cross-sectional view taken along line AA in FIG. 93. [Figure 95] FIG. 94 is a schematic cross-sectional view taken along line BB in FIG. 93. [Figure 96A] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96B] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96C] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96D]1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96E] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96F] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96G] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96H] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96I] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96J] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 96K] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. [Figure 97] FIG. 10 is a schematic circuit diagram illustrating the operation of a display device according to another exemplary embodiment of the present disclosure. [Figure 98] FIG. 10 is a schematic plan view of a display device according to another exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0220] Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to fully convey the concept of the present disclosure to those skilled in the art to which the present disclosure pertains. Therefore, the present disclosure is not limited to the embodiments disclosed herein and may be embodied in other forms. In the drawings, the width, length, thickness, etc. of elements may be exaggerated for clarity and illustrative purposes. When an element or layer is referred to as being "disposed on" or "disposed on" another element or layer, the element or layer may be directly "disposed on" or "disposed on" the other element or layer, or there may be intervening elements or layers. Throughout the specification, the same reference numerals refer to the same elements having the same or similar function.

[0221] DETAILED DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. As used herein, a light emitting device or light emitting diode according to an exemplary embodiment has a diameter of about 10,000 μm, as is known in the art. 2 In other exemplary embodiments, the micro LEDs may include micro LEDs having a surface area of ​​less than about 4,000 μm, depending on the particular application. 2 Less than or about 2,500 μm 2 It may have a surface area of ​​less than 1000 nm.

[0222] FIG. 1 is a schematic cross-sectional view of a light emitting diode stack 100 for a display according to one exemplary embodiment of the present disclosure.

[0223] Referring to FIG. 1, the light-emitting diode stack 100 may include a support substrate 51, a second substrate 31, a third substrate 41, a first LED stack 23, a second LED stack 33, a third LED stack 43, a first-p reflective electrode 25, a second-p transparent electrode 35, a third-p transparent electrode 45, a first color filter 37, a second color filter 47, a first bonding layer 53, a second bonding layer 55, and a third bonding layer 57.

[0224] The support substrate 51 supports the semiconductor stacks 23, 33, and 43. The support substrate 51 may include, but is not limited to, circuitry on or within its surface. The support substrate 51 may include, for example, a Si substrate or a Ge substrate.

[0225] Each of the first LED stack 23, the second LED stack 33, and the third LED stack 43 includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed therebetween. The active layer may have a multiple quantum well structure.

[0226] For example, the first LED stack 23 may be an inorganic light emitting diode adapted to emit red light, the second LED stack 33 may be an inorganic light emitting diode adapted to emit green light, and the third LED stack 43 may be an inorganic light emitting diode adapted to emit blue light. The first LED stack 23 may include a GaInP-based well layer, and each of the second LED stack 33 and the third LED stack 43 may include a GaInN-based well layer.

[0227] At the same time, both surfaces of each of the first to third LED stacks 23, 33, and 43 are n-type and p-type semiconductor layers, respectively. In this exemplary embodiment, each of the first to third LED stacks 23, 33, and 43 has an n-type upper surface and a p-type lower surface. Because the third LED stack 43 has an n-type upper surface, a roughened surface is formed on the upper surface of the third LED stack 43 by chemical etching. However, it should be understood that the present disclosure is not limited in this respect, and the semiconductor types of the upper and lower surfaces of each LED stack can vary.

[0228] The first LED stack 23 is disposed near the support substrate 51, the second LED stack 33 is disposed on the first LED stack 23, and the third LED stack 43 is disposed on the second LED stack 33. Since the first LED stack 23 emits light having a longer wavelength than the second and third LED stacks 33 and 43, light generated from the first LED stack 23 is emitted to the outside via the second and third LED stacks 33 and 43. Furthermore, since the second LED stack 33 emits light having a longer wavelength than the third LED stack 43, light generated from the second LED stack 33 is emitted to the outside via the third LED stack 43.

[0229] The second substrate 31 is a growth substrate for the second LED stack 33 and may be, for example, a GaN-based substrate. The second substrate 31 is a homogeneous substrate for the second LED stack 33 and is monolithically bonded to the second LED stack 33. The second substrate 31 is doped with an n-type dopant, such as Si, to serve as an n-type semiconductor layer. Because a homogeneous substrate for the second LED stack 33 is used as the second substrate 31, the dislocation density of the second LED stack 33 grown on the second substrate 31 can be reduced, thereby improving the luminous efficiency of the second LED stack 33. The second LED stack 33 may have a dislocation density of, for example, 103 to 107 / cm2. Because GaN-based semiconductor layers grown on a sapphire substrate generally have a dislocation density of 108 / cm2 or more, the dislocation density of the second LED stack 33 can be significantly reduced by using a GaN growth substrate.

[0230] The third substrate 41 is a growth substrate for the third LED stack 43 and may be a GaN-based substrate, for example, a GaN substrate. The third substrate 41 is a homogeneous substrate for the third LED stack 43 and is monolithically bonded to the third LED stack 43. The third substrate 41 is doped with an n-type dopant, such as Si, to be used as an n-type semiconductor layer. Because a homogeneous substrate for the third LED stack 43 is used as the third substrate 41, the dislocation density of the third LED stack 43 grown on the third substrate 41 can be reduced, thereby improving the luminous efficiency of the third LED stack 43. The third LED stack 43 may have a dislocation density of, for example, 103 to 107 / cm2.

[0231] Although both the second substrate 31 and the third substrate 41 are used in this exemplary embodiment, one of the second substrate 31 and the third substrate 41 can be omitted, and both the second substrate 31 and the third substrate 41 can be removed as described below with reference to FIG.

[0232] The first-p reflective electrode 25 forms ohmic contact with the p-type semiconductor layer of the first LED stack 23 and reflects light generated from the first LED stack 23. For example, the first-p reflective electrode 25 is made of Au—Ti or Au—Sn. The first-p reflective electrode 25 may also include a diffusion barrier layer.

[0233] The second-p transparent electrode 35 forms an ohmic contact with the p-type semiconductor layer of the second LED stack 33. The second-p transparent electrode 35 is made of a metal layer or a conductive oxide layer that is transparent to red and green light.

[0234] In addition, the third-p transparent electrode 45 forms an ohmic contact with the p-type semiconductor layer of the third LED stack 43. The third-p transparent electrode 45 is composed of a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0235] The first p-reflective electrode 25, the second p-transparent electrode 35 and the third p-transparent electrode 45 can assist current spreading by making ohmic contact with the p-type semiconductor layer of each LED stack.

[0236] The first color filter 37 may be interposed between the first LED stack 23 and the second LED stack 33. In addition, the second color filter 47 may be interposed between the second LED stack 33 and the third LED stack 43. The first color filter 37 transmits light generated from the first LED stack 23 while reflecting light generated from the second LED stack 33. The second color filter 47 transmits light generated from the first and second LED stacks 23 and 33 while reflecting light generated from the third LED stack 43. As a result, the light generated from the first LED stack 23 is emitted to the outside via the second LED stack 33 and the third LED stack 43, and the light generated from the second LED stack 33 is emitted to the outside via the third LED stack 43. In addition, the light emitting diode stack can prevent light generated from the second LED stack 33 from entering the first LED stack 23 or can prevent light generated from the third LED stack 43 from entering the second LED stack 33, thereby preventing light loss. Meanwhile, light generated from the first LED stack 23 is emitted to the outside through the second-p transparent electrode 35 and the third-p transparent electrode 45, and light generated from the second LED stack 33 is emitted to the outside through the third-p transparent electrode 45.

[0237] In some exemplary embodiments, the first color filter 37 can reflect the light generated from the third LED stack 43 .

[0238] The first and second color filters 37 and 47 may be, for example, low-pass filters that pass light in a low-frequency band (i.e., a long-wavelength band), band-pass filters that pass light in a predetermined wavelength band, or band-stop filters that prevent light from passing in a predetermined wavelength band. In particular, each of the first and second color filters 37 and 47 may be a band-stop filter including a distributed Bragg reflector (DBR). A distributed Bragg reflector can be formed by alternately stacking insulating layers with different refractive indices, such as TiO2 and SiO2. At the same time, the stop band of the distributed Bragg reflector can be controlled by adjusting the thickness of the TiO2 and SiO2 layers. Low-pass and band-pass filters can also be formed by alternately stacking insulating layers with different refractive indices.

[0239] The first bonding layer 53 bonds the first LED stack 23 to the support substrate 51. As shown, the first-p reflective electrode 25 may be adjacent to the first bonding layer 53. The first bonding layer 53 may be a light-transmitting or opaque layer. The first bonding layer 53 may be, for example, a transparent inorganic insulating layer, a transparent organic insulating layer, or a transparent conductive layer.

[0240] The second bonding layer 55 bonds the second LED stack 33 to the first LED stack 23. As shown, the second bonding layer 55 may be adjacent to the first LED stack 23 and the first color filter 37. However, it should be understood that the present disclosure is not limited in this respect, and a transparent conductive layer may be disposed on the first LED stack 23. The second bonding layer 55 transmits light generated from the first LED stack 23. The second bonding layer 55 may be, for example, a transparent inorganic insulating layer, a transparent organic insulating layer, or a transparent conductive layer, and may be formed, for example, of light-transmitting spin-on glass.

[0241] The third bonding layer 57 bonds the third LED stack 43 to the second LED stack 33. As shown, the third bonding layer 57 may be adjacent to the second substrate 31, which is monolithically bonded to the second LED stack 33, or may be adjacent to the second color filter 47. However, it should be understood that the present disclosure is not limited thereto. If the second substrate 31 is omitted, the third bonding layer 57 may be adjacent to the second LED stack 33. Alternatively, a transparent conductive layer may be disposed on the second LED stack 33 or the second substrate 31, and the third bonding layer 57 may be adjacent to the transparent conductive layer. The third bonding layer 57 transmits light generated from the first LED stack 23 and the second LED stack 33. The third bonding layer 57 may be, for example, a transparent inorganic insulating layer, a transparent organic insulating layer, or a transparent conductive layer, and may be formed, for example, of light-transmitting spin-on glass.

[0242] FIG. 2 is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack for a display according to one exemplary embodiment of the present disclosure.

[0243] Referring to FIG. 2, first, a first LED stack 23 is grown on a first substrate 21, and a first-p reflective electrode 25 is formed on the first LED stack 23.

[0244] The first substrate 21 may be, for example, a GaAs substrate. Additionally, the first LED stack 23 is made of AlGaInP-based semiconductor layers, including an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. The first-p reflective electrode 25 forms ohmic contact with the p-type semiconductor layer.

[0245] Meanwhile, the second LED stack 33 is grown on the second substrate 31, and the second-p transparent electrode 35 and the first color filter 37 are formed on the second LED stack 33. The second LED stack 33 is composed of a GaN-based semiconductor layer and may include a GaInN well layer. The second substrate 31 is a homogeneous substrate for the GaN-based semiconductor layer and may be, for example, a GaN substrate. Alternatively, the second substrate 31 may be an n-type semiconductor doped with an n-type dopant. The composition ratio of GaInN for the second LED stack 33 may be determined so that the second LED stack 33 emits green light. Meanwhile, the second-p transparent electrode 35 forms ohmic contact with the p-type semiconductor layer.

[0246] Furthermore, a third LED stack 43 is grown on the third substrate 41, and a third-p transparent electrode 45 and a second color filter 47 are formed on the third LED stack 43. The third LED stack 43 is composed of a GaN-based semiconductor layer and may include a GaInN well layer. The third substrate 41 is a homogeneous substrate for the GaN-based semiconductor layer and may be, for example, a GaN substrate. The composition ratio of GaInN for the third LED stack 43 may be determined so that the third LED stack 43 emits blue light. Meanwhile, the third-p transparent electrode 45 forms ohmic contact with the p-type semiconductor layer.

[0247] The first color filter 37 and the second color filter 47 are the same as those described with reference to FIG. 1, and a repeated description thereof will be omitted.

[0248] 1 and 2, the first LED stack 23 is bonded to the support substrate 51 via a first bonding layer 53. The first bonding layer 53 may be pre-formed on the support substrate 51, and the first-p reflective electrode 25 may be disposed facing the support substrate 51 and bonded to the first bonding layer 53. The first substrate 21 is removed from the first LED stack 23 by chemical etching.

[0249] Thereafter, the second LED stack 33 is bonded to the first LED stack 23 via the second bonding layer 55. The first color filter 37 is disposed facing the first LED stack 23 and bonded to the second bonding layer 55. The second bonding layer 55 may be pre-formed on the first LED stack 23, and the first color filter 37 may be disposed facing the second bonding layer 55 and bonded to the second bonding layer 55. The second substrate 31 may have a reduced thickness due to a thinning process compared to when the second substrate is used as a growth substrate. Alternatively, the entire second substrate 31 may be removable.

[0250] Thereafter, the third LED stack 43 is bonded to the second LED stack 33 via the third bonding layer 57. The second color filter 47 is arranged facing the second substrate 31 and bonded to the third bonding layer 57. The third bonding layer 57 may be pre-arranged on the second substrate 31, and the second color filter 47 may be arranged facing the third bonding layer 57 and bonded to the third bonding layer 57. As a result, a light-emitting diode stack for a display is provided, having the third LED stack 43 exposed to the outside, as shown in FIG. 1 . The third substrate 41 may be further thinned or completely removed.

[0251] A display device can be provided by patterning stacks of first to third LED stacks 23, 33 and 43 on a supporting substrate 51 in a pixel unit, and then connecting the first to third LED stacks to each other via interconnection lines. Exemplary embodiments of the display device will be described below.

[0252] FIG. 3 is a schematic circuit diagram illustrating the operation of a display device according to one exemplary embodiment of the present disclosure, and FIG. 4 is a schematic plan view of a display device according to an exemplary embodiment of the present disclosure.

[0253] Referring first to Figures 3 and 4, a display device according to this exemplary embodiment can be implemented to operate in a passive matrix manner.

[0254] 1 has a structure in which first to third LED stacks 23, 33, and 43 are stacked vertically, so that one pixel includes three light emitting diodes R, G, and B. The first light emitting diode R corresponds to the first LED stack 23, the second light emitting diode G corresponds to the second LED stack 33, and the third light emitting diode B corresponds to the third LED stack 43.

[0255] 3 and 4, one pixel includes first to third light-emitting diodes R, G, and B, each of which corresponds to a subpixel. The anodes of the first to third light-emitting diodes R, G, and B are connected to a common line, such as a data line, and the cathodes are connected to different lines, such as scan lines. For example, in the first pixel, the anodes of the first to third light-emitting diodes R, G, and B are commonly connected to the data line Vdata1, and the cathodes are connected to scan lines Vscan1-1, Vscan1-2, and Vscan1-3, respectively. As a result, the light-emitting diodes R, G, and B in each pixel can be driven independently.

[0256] Additionally, each of the light emitting diodes R, G and B is driven by pulse width modulation or by varying the magnitude of the current, thereby allowing adjustment of the brightness of each sub-pixel.

[0257] Referring again to Figure 4, a plurality of pixels are formed by patterning the stack described with reference to Figure 1, and each pixel is connected to a first-p reflective electrode 25 and interconnection lines 71, 73 and 75. As shown in Figure 3, the first-p reflective electrode 25 can be used as a data line Vdata, and the interconnection lines 71, 73 and 75 can be formed as scan lines.

[0258] The pixels are arranged in a matrix, with the anodes of the light-emitting diodes R, G, and B of each pixel connected in common to the first-p reflective electrode 25, and the cathodes connected to interconnection lines 71, 73, and 75 that are separated from each other. The interconnection lines 71, 73, and 75 can be used as scan lines Vscan.

[0259] 5 is an enlarged plan view of one pixel of the display device shown in FIG. 4, FIG. 6 is a schematic cross-sectional view taken along line AA in FIG. 5, and FIG. 7 is a schematic cross-sectional view taken along line BB in FIG. 5.

[0260] Referring to Figures 4, 5, 6 and 7, in each pixel, a portion of the first-p reflective electrode 25, a portion of the upper surface of the first LED stack 23, a portion of the second-p transparent electrode 35, a portion of the upper surface of the second substrate 31, a portion of the third-p transparent electrode 45, and the upper surface of the third substrate 41 are exposed to the outside.

[0261] The third LED stack 43 may have a roughened surface 43a on its top surface. The roughened surface 43a may be formed across the entire top surface of the third substrate 41, as shown, or may be formed in some areas thereof. In structures in which the third substrate 41 is removed, a roughened surface is formed on the third LED stack 43.

[0262] The first insulating layer 61 may cover the side surfaces of each pixel. The first insulating layer 61 may be formed of an optically transparent material such as SiO2. In this case, the first insulating layer 61 may cover the entire upper surface of the third substrate 41. Alternatively, the first insulating layer 61 may include a distributed Bragg reflector to reflect light traveling toward the side surfaces of the first to third LED stacks 23, 33, and 43. In this case, the first insulating layer 61 at least partially exposes the upper surface of the third substrate 41.

[0263] The first insulating layer 61 may include an opening 61a exposing the upper surface of the third substrate 41, an opening 61b exposing the upper surface of the second substrate 31, an opening 61c (see Figure 8H) exposing the ohmic electrode 29 of the first LED stack 23, an opening 61d exposing the third-p transparent electrode 45, an opening 61e exposing the second-p transparent electrode 35, and an opening 61f exposing the first-p reflective electrode 25.

[0264] The interconnection lines 71 and 75 are formed on the support substrate 51 near the first to third LED stacks 23, 33, and 43, and are disposed on the first insulating layer 61 so as to be insulated from the first-p reflective electrode 25. Meanwhile, a connection portion 77a connects the third-p transparent electrode 45 to the first-p reflective electrode 25, and a connection portion 77b connects the second-p transparent electrode 35 to the first-p reflective electrode 25, so that the anodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43 are commonly connected to the first-p reflective electrode 25.

[0265] The connection portion 71 a connects the top surface of the third substrate 41 to the interconnection line 71 , and the connection portion 75 a connects the top surface of the first LED stack 23 to the interconnection line 75 .

[0266] A second insulating layer 81 may be disposed on the interconnection lines 71 and 73 and cover the top surface of the third substrate 41. The second insulating layer 81 may have an opening 81a that partially exposes the top surface of the second substrate 31.

[0267] The interconnection line 73 is disposed on the second insulating layer 81, and the connecting portion 73a can connect the upper surface of the second substrate 31 to the interconnection line 73. The connecting portion 73a can pass through the upper portion of the interconnection line 75 and is insulated from the interconnection line 75 by the second insulating layer 81.

[0268] Although the electrode of each pixel is described as being connected to a data line and a scan line in this exemplary embodiment, it should be understood that various embodiments are possible. In this exemplary embodiment, interconnection lines 71 and 75 are formed on the first insulating layer 61, and interconnection line 73 is formed on the second insulating layer 81, but it should be understood that the present disclosure is not limited thereto. For example, all interconnection lines 71, 73, and 75 may be formed on the first insulating layer 61 and covered by the second insulating layer 81, which may have an opening configured to expose the interconnection line 73. In this structure, the connecting portion 73a can connect the upper surface of the second substrate 31 to the interconnection line 73 through the opening in the second insulating layer 81.

[0269] Alternatively, the interconnection lines 71, 73 and 75 may be formed inside the support substrate 51, and connection portions 71a, 73a and 75a on the first insulating layer 61 may connect the upper surface of the first LED stack 23 and the upper surfaces of the second and third substrates 31 and 41 to the interconnection lines 71, 73 and 75.

[0270] 8A-8K are schematic cross-sectional views illustrating a method for manufacturing a display device according to one exemplary embodiment of the present disclosure. The following description is given regarding a method for forming the pixel of FIG.

[0271] First, the light-emitting diode stack 100 described in FIG. 1 is prepared.

[0272] 8A, a roughened surface 41a is formed on the upper surface of the third substrate 41. The roughened surface 41a is formed on the upper surface of the third substrate 41 so as to correspond to each pixel area. The roughened surface 41a is formed by chemical etching, for example, photo-enhanced chemical etching (PEC).

[0273] The roughened surface 41 a may be formed partially within each pixel area in consideration of the area of ​​the third substrate 41 that will be etched in a subsequent process, but is not limited to this. Alternatively, the roughened surface 41 a may be formed over the entire upper surface of the third substrate 41.

[0274] 8B , the peripheral area of ​​the third substrate 41 and the third LED stack 43 in each pixel is etched away to expose the third-p transparent electrode 45. As shown, the third substrate 41 can be held to have a rectangular or square shape. A plurality of depressions are formed along the periphery of the third substrate 41 and the third LED stack 43. These depressions may be formed continuously on the third substrate 41 and the third LED stack 43.

[0275] 8C, the upper surface of the second substrate 31 is exposed by removing the third-p transparent electrode 45 exposed in other regions except for a portion of the third-p transparent electrode 45 exposed in one of the recesses. Thus, the upper surface of the second substrate 31 is exposed around the third substrate 41 and in the other recesses except for the recess where the third-p transparent electrode 45 partially remains.

[0276] Referring to FIG. 8D, the second substrate 31 exposed in other areas except for a portion of the second substrate 31 exposed within one recess is removed, and then the second LED stack 33 is removed, thereby exposing the second-p transparent electrode 35.

[0277] 8E , the upper surface of the first LED stack 23 is exposed by removing the second-p transparent electrode 35 exposed in other regions except for a portion of the second-p transparent electrode 35 exposed in one of the recesses. Thus, the upper surface of the first LED stack 23 is exposed around the periphery of the third substrate 41, and the upper surface of the first LED stack 23 is exposed in at least one of the recesses formed in the third substrate 41.

[0278] 8F, the first-p reflective electrode 25 is exposed by removing the exposed portion of the first LED stack 23 in the other region except for the first LED stack 23 exposed in one of the recesses. The first-p reflective electrode 25 is exposed around the periphery of the third substrate 41.

[0279] 8G, a linear interconnection line is formed by patterning the first-p reflective electrode 25. Here, the support substrate 51 may be exposed. The first-p reflective electrode 25 can connect pixels arranged in one row among the pixels arranged in a matrix (see FIG. 4).

[0280] Referring to FIG. 8H, a first insulating layer 61 (see FIGS. 6 and 7) is formed to cover the pixel. The first insulating layer 61 covers the first-p reflective electrode 25, the side surfaces of the first to third LED stacks 23, 33, and 43, and the side surfaces of the second and third substrates 31 and 41. In addition, the first insulating layer 61 may at least partially cover the top surface of the third substrate 41. If the first insulating layer 61 is a transparent layer such as a SiO2 layer, the first insulating layer 61 may cover the entire top surface of the third substrate 41. Alternatively, the first insulating layer 61 may include a distributed Bragg reflector. In this case, the first insulating layer 61 may at least partially expose the top surface of the third substrate 41, allowing light to be emitted to the outside.

[0281] The first insulating layer 61 can include an opening 61a exposing the third substrate 41, an opening 61b exposing the second substrate 31, an opening 61c exposing the first LED stack 23, an opening 61d exposing the third-p transparent electrode 45, an opening 61e exposing the second-p transparent electrode 35, and an opening 61f exposing the first-p reflective electrode 25. A plurality of openings 61f adapted to expose the first-p reflective electrode 25 may be formed.

[0282] 8I, interconnection lines 71 and 75 and connecting portions 71a, 75a, 77a, and 77b are formed by a lift-off process. The interconnection lines 71 and 75 are insulated from the first-p reflective electrode 25 by a first insulating layer 61. The connecting portion 71a electrically connects the third substrate 41 to the interconnection line 71, and the connecting portion 75a electrically connects the first LED stack 23 to the interconnection line 75. The connecting portion 77a electrically connects the third-p transparent electrode 45 to the first-p reflective electrode 25, and the connecting portion 77b electrically connects the second-p transparent electrode 35 to the first-p reflective electrode 25.

[0283] Referring to FIG. 8J, a second insulating layer 81 (see FIGS. 6 and 7) covers the interconnection lines 71 and 75 and the connecting portions 71a, 75a, 77a, and 77b. The second insulating layer 81 may also cover the entire upper surface of the third substrate 41. The second insulating layer 81 has an opening 81a that exposes the upper surface of the second substrate 31. The second insulating layer 81 may be formed of, for example, silicon oxide or silicon nitride, and may include a distributed Bragg reflector. In a structure in which the second insulating layer 81 includes a distributed Bragg reflector, the second insulating layer 81 is formed to expose at least a portion of the upper surface of the third substrate 41, allowing light to be emitted to the outside.

[0284] 8K, the interconnection line 73 and the connecting portion 73a are formed. The interconnection line 75 and the connecting portion 73a are formed by a lift-off process. The interconnection line 73 is disposed on a second insulating layer 81 and is insulated from the first-p reflective electrode 25 and the interconnection lines 71 and 75. The connecting portion 73a electrically connects the second substrate 31 to the interconnection line 73. The connecting portion 73a can penetrate the upper portion of the interconnection line 75 and is insulated from the interconnection line 75 by the second insulating layer 81.

[0285] As a result, the pixel area is completed as shown in Fig. 5. In addition, as shown in Fig. 4, a plurality of pixels are formed on the support substrate 51 and connected to each other by the first-p reflective electrode 25 and the interconnection lines 71, 73 and 75, so as to be operable in a passive matrix manner.

[0286] Although a method for manufacturing a display device adapted to operate in a passive matrix manner has been shown in this exemplary embodiment, it should be understood that the present disclosure is not limited thereto. That is, display devices according to exemplary embodiments can be manufactured in a variety of ways to operate in a passive matrix manner using the light emitting diode stack shown in FIG.

[0287] For example, in this illustrative embodiment, interconnection line 73 is shown as being formed on second insulating layer 81, but interconnection line 73 may be formed on first insulating layer 61 along with interconnection lines 71 and 75, and connecting portion 73a may be formed on second insulating layer 81 to connect second substrate 31 to interconnection line 73. Alternatively, interconnection lines 71, 73, and 75 may be disposed within support substrate 51.

[0288] 9 is a schematic circuit diagram illustrating the operation of a display device according to another exemplary embodiment of the present disclosure. While the above-described embodiments relate to display devices driven by a passive matrix method, this exemplary embodiment relates to a display device driven by an active matrix method.

[0289] Referring to FIG. 9, the driving circuit according to this exemplary embodiment includes two or more transistors Tr1 and Tr2 and a capacitor. When a power supply is connected to the select lines Vrow1 to Vrow3 and a voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding light-emitting diode. In addition, the corresponding capacitor is charged according to the value of the data lines Vdata1 to Vdata3. Since the turn-on state of the transistor Tr2 can be maintained by the charged voltage of the capacitor, the voltage of the capacitor is maintained and applied to the light-emitting diodes LED1 to LED3 even when the power supplied to the select line Vrow1 is cut off. In addition, the current flowing in the light-emitting diodes LED1 to LED3 can be changed according to the value of the data lines Vdata1 to Vdata3. The current can be continuously supplied via a current supply source Vdd, thereby enabling continuous light emission.

[0290] The transistors Tr1 and Tr2 and the capacitor are formed inside the support substrate 51. For example, thin film transistors formed on a silicon substrate can be used for active matrix driving.

[0291] The light-emitting diodes LED1 to LED3 correspond to the first to third LED stacks 23, 33, and 43, respectively, stacked in one pixel. The anodes of the first to third LED stacks are connected to a transistor Tr2, and the cathodes thereof are connected to ground.

[0292] Although one example of a circuit for active matrix driving is shown in this exemplary embodiment, it should be understood that other types of circuits can also be used. In addition, in this exemplary embodiment, the anodes of the light emitting diodes LED1 to LED3 are connected to different transistors Tr2 and their cathodes are connected to ground, but in other exemplary embodiments, the anodes of the light emitting diodes may be connected to a current supply source Vdd and their cathodes may be connected to different transistors.

[0293] 10 is a schematic plan view of a display device according to another exemplary embodiment of the present disclosure. The following description will be given for one pixel among a plurality of pixels arranged on a support substrate 151.

[0294] Referring to FIG. 10, the pixel according to this illustrative embodiment is substantially similar to the pixel described with reference to FIGS. 4 to 7, except that the supporting substrate 151 is a thin film transistor panel including transistors and capacitors, and the first-p reflective electrode 25 is confined within the lower region of the first LED stack 23.

[0295] The cathode of the third LED stack 43 is connected to the support substrate 151 via the connection portion 171a. For example, as shown in Fig. 9, the cathode of the third LED stack 43 is connected to ground by an electrical connection to the support substrate 151. The cathodes of the second LED stack 33 and the first LED stack 23 may also be connected to ground by an electrical connection to the support substrate 151 via the connection portions 173a and 175a.

[0296] On the other hand, the first-p reflective electrode 25 is connected to the transistor Tr2 (see FIG. 9) inside the support substrate 151. The third-p transparent electrode 45 and the second-p transparent electrode 35 are also connected to the transistor Tr2 (see FIG. 9) inside the support substrate 151 via connection portions 171a and 173b.

[0297] In this manner, the first to third LED stacks 23, 33 and 43 are connected to one another, thereby forming a circuit for active matrix driving, as shown in FIG.

[0298] Although one example of electrical connections for active matrix driving is shown in this exemplary embodiment, it should be understood that the present disclosure is not limited thereto and that the circuit for the display device can be modified in various ways into various circuits for active matrix driving.

[0299] 1, the first-p reflective electrode 25, the second-p transparent electrode 35, and the third-p transparent electrode 45 form ohmic contacts with the p-type semiconductor layers of the first LED stack 23, the second LED stack 33, and the third LED stack 43, respectively, but separate ohmic contact layers are not provided on the second substrate 31 and the third substrate 41. When the pixel has a small size of 200 μm or less, there is no difficulty in current spreading even if a separate ohmic contact layer is not formed in the n-type semiconductor layer. However, to ensure current spreading, a transparent electrode layer may be disposed on each of the second substrate 31 and the third substrate 41.

[0300] In addition, the first to third LED stacks 23, 33 and 43 are connected to each other in various structures.

[0301] FIG. 11 is a schematic cross-sectional view of a light-emitting diode stack 101 for a display according to another exemplary embodiment of the present disclosure.

[0302] 1 , like the light-emitting diode stack 100 described with reference to Fig. 1 , the light-emitting diode stack 101 includes a support substrate 51, a first LED stack 23, a second LED stack 33, a third LED stack 43, a second substrate 31, a third substrate 41, a second-p transparent electrode 35, a third-p transparent electrode 45, a first color filter 137, a second color filter 47, a first bonding layer 153, a second bonding layer 155, and a third bonding layer 157. In addition, the light-emitting diode stack 101 may further include a first-n reflective electrode 129, a first-p transparent electrode 125, and a second-n transparent electrode 139.

[0303] The support substrate 51 supports the semiconductor stacks 23, 33, and 43. The support substrate 51 may include, but is not limited to, circuitry on or within its surface. The support substrate 51 may include, for example, a Si substrate or a Ge substrate.

[0304] The first LED stack 23, the second LED stack 33, and the third LED stack 43 are similar to those described with reference to Fig. 1, and a detailed description thereof will be omitted. However, this exemplary embodiment differs from the exemplary embodiment shown in Fig. 1 in that the first LED stack 23 and the second LED stack 33 each have an n-type bottom surface and a p-type top surface. As in the exemplary embodiment shown in Fig. 1, the third LED stack 43 according to this exemplary embodiment has a p-type bottom surface and an n-type top surface.

[0305] The second substrate 31 and the third substrate 41 are similar to those described with reference to FIG. 1, and a detailed description thereof will be omitted.

[0306] Meanwhile, since the first LED stack 23 has a p-type upper surface, the first-p transparent electrode 125 forms an ohmic contact with the upper surface of the first LED stack 23. The first-p transparent electrode 125 transmits light, for example, red light, generated from the first LED stack 23.

[0307] The 1-n reflective electrodes 129 form ohmic contact with the lower surface of the first LED stack 23. The 1-n reflective electrodes 129 form ohmic contact with the first LED stack 23 and reflect light generated from the first LED stack 23. The 1-n reflective electrodes 129 are formed of, for example, Au—Ti or Au—Sn. The 1-n reflective electrodes 129 may also include a diffusion barrier layer.

[0308] The second-p transparent electrode 35 forms an ohmic contact with the p-type semiconductor layer of the second LED stack 33. Because the second LED stack 33 has a p-type upper surface, the second-p transparent electrode 35 is disposed on the second LED stack 33. The second-p transparent electrode 35 is composed of a metal layer or a conductive oxide layer that is transparent to red and green light.

[0309] The second-n transparent electrode 139 can form an ohmic contact with the lower surface of the second substrate 31. The second-n transparent electrode 139 is also composed of a metal layer or a conductive oxide layer that is transparent to red and green light. The second-n transparent electrode 139 is partially exposed by patterning the second LED stack 33 and the second substrate 31 to provide a connection terminal for electrical connection to the n-type semiconductor layer of the second LED stack 33.

[0310] The third-p transparent electrode 45 forms an ohmic contact with the p-type semiconductor layer of the third LED stack 43. The third-p transparent electrode 45 is made of a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0311] The first color filter 137 is interposed between the first LED stack 23 and the second LED stack 33. In addition, the second color filter 47 is interposed between the second LED stack 33 and the third LED stack 43. The first color filter 137 transmits light generated from the first LED stack 23 and reflects light generated from the second LED stack 33. On the other hand, the second color filter 47 transmits light generated from the first and second LED stacks 23 and 33 and reflects light generated from the third LED stack 43. Therefore, the light generated from the first LED stack 23 is emitted to the outside via the second substrate 31, the second LED stack 33, the third LED stack 43, and the third substrate 41, and the light generated from the second LED stack 33 is emitted to the outside via the third LED stack 43 and the third substrate 41. Furthermore, the light-emitting diode stack 101 can prevent light generated from the second LED stack 33 from entering the first LED stack 23 and can prevent light generated from the third LED stack 43 from entering the second LED stack 33, thereby preventing light loss. Light generated from the first LED stack 23 is emitted to the outside through the first-p transparent electrode 125, the second-p transparent electrode 35, the second-n transparent electrode 139, and the third-p transparent electrode 45. Furthermore, light generated from the second LED stack 33 is emitted to the outside through the second-p transparent electrode 35 and the third-p transparent electrode 45.

[0312] In some exemplary embodiments, the first color filter 137 can reflect the light generated from the third LED stack 43 .

[0313] The first and second color filters 137 and 47 may be, for example, low-pass filters that allow light to pass through them in a low frequency band, i.e., a long wavelength band, band-pass filters that allow light to pass through them in a predetermined wavelength band, or band-stop filters that prevent light from passing through them in a predetermined wavelength band. In particular, each of the first and second color filters 137 and 47 may be a band-stop filter including a distributed Bragg reflector (DBR). A distributed Bragg reflector can be formed by alternately stacking insulating layers having different refractive indices, such as TiO2 and SiO2. At the same time, the stop band of the distributed Bragg reflector can be controlled by adjusting the thickness of the TiO2 and SiO2 layers. Low-pass filters and band-pass filters can also be formed by alternately stacking insulating layers having different refractive indices.

[0314] The first bonding layer 153 bonds the first LED stack 23 to the support substrate 51. As shown, the first-n reflective electrodes 129 may be adjacent to the first bonding layer 153. The first bonding layer 153 may be a light-transmitting or opaque layer. The first bonding layer 153 may be, for example, a transparent inorganic insulating layer, a transparent organic insulating layer, or a transparent conductive layer.

[0315] The second bonding layer 155 couples the second LED stack 33 to the first LED stack 23. As shown, the second bonding layer 155 may be disposed on the first color filter 137 and adjacent to the second-n transparent electrode 139. The second bonding layer 155 transmits light generated from the first LED stack 23. The second bonding layer 155 may be, for example, a transparent inorganic insulating layer, a transparent organic insulating layer, or a transparent conductive layer, and may be formed, for example, of light-transmitting spin-on glass.

[0316] The third bonding layer 157 bonds the third LED stack 43 to the second LED stack 33. As shown, the third bonding layer 157 may be adjacent to the second-p transparent electrode 35 and the second color filter 47. The third bonding layer 157 transmits light generated from the first LED stack 23 and the second LED stack 33. The third bonding layer 157 may be, for example, a transparent inorganic insulating layer, a transparent organic insulating layer, or a transparent conductive layer, and may be formed, for example, of light-transmitting spin-on glass.

[0317] 12A to 12F are schematic cross-sectional views illustrating a method for manufacturing a light-emitting diode stack for a display according to yet another exemplary embodiment of the present disclosure.

[0318] 12A , first, a third LED stack 43 is grown on a third substrate 41, and then a third-p transparent electrode 45 and a second color filter 47 are formed on the third LED stack 43. The third LED stack 43 is composed of a GaN-based semiconductor layer and may include a GaInN well layer. The third substrate 41 is a homogeneous substrate for the GaN-based semiconductor layer and may be, for example, a GaN substrate doped with an n-type dopant. The composition ratio of GaInN for the third LED stack 43 may be determined so that the third LED stack 43 emits blue light. The third-p transparent electrode 45 forms ohmic contact with the p-type semiconductor layer.

[0319] 12B, a second LED stack 33 is grown on a second substrate 31, and a second-p transparent electrode 35 is formed on the second LED stack 33. The second LED stack 33 is composed of a GaN-based semiconductor layer and may include a GaInN well layer. The second substrate 31 is a homogeneous substrate for the GaN-based semiconductor layer and may be, for example, a GaN substrate doped with an n-type dopant. The composition ratio of GaInN for the second LED stack 33 may be determined so that the second LED stack 33 emits green light. Meanwhile, the second-p transparent electrode 35 forms ohmic contact with the p-type semiconductor layer.

[0320] The second substrate 31 is disposed such that the third bonding layer 157 is provided on the second color filter 47 and the second-p transparent electrode 35 on the second substrate 31 is adjacent to the third bonding layer 157. The third bonding layer 157 is formed of, for example, spin-on glass. Thus, the second LED stack 33 is bonded to the third LED stack 43.

[0321] 12C, the 2-n transparent electrode 139 is formed on the second substrate 31. The 2-n transparent electrode 139 forms an ohmic contact with the second substrate 31. The 2-n transparent electrode 139 is composed of a metal layer or a conductive oxide layer. The 2-n transparent electrode 139 is optional.

[0322] Referring to FIG. 12D, a first LED stack 23 is grown on a first substrate 21, a first-p transparent electrode 125 is formed on the first LED stack 23, and a first color filter 137 is formed on the first-p transparent electrode 125.

[0323] The first substrate 21 may be, for example, a GaAs substrate. Additionally, the first LED stack 23 is made of AlGaInP-based semiconductor layers, including an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. The first-p transparent electrode 125 forms ohmic contact with the p-type semiconductor layer.

[0324] The first color filter 137 is substantially the same as that described with reference to FIG. 1, and a detailed description thereof will be omitted to avoid repetition.

[0325] Thereafter, a second bonding layer 155 is provided on the second-n transparent electrode 139, and the second substrate 31 is disposed such that the first color filter 137 on the first substrate 21 is adjacent to the second bonding layer 155. The second bonding layer 155 is formed of, for example, spin-on glass. Thus, the first LED stack 23 is bonded to the second LED stack 33.

[0326] 12E, the first LED stack 23 is bonded to the second LED stack 33, and the first substrate 21 is removed from the first LED stack 23 by chemical etching. As a result, the first LED stack 23 is exposed.

[0327] 12F, the 1-n reflective electrodes 129 are formed on the exposed first LED stack 23. The 1-n reflective electrodes 129 include a metal layer that reflects light generated from the first LED stack 23.

[0328] Then, a first bonding layer 153 is disposed on the first-n reflective electrodes 129, and a support substrate 51 is bonded thereto. As a result, a light-emitting diode stack 101 having an externally exposed third substrate 41 is provided, as shown in FIG.

[0329] A display device can be provided by patterning a stack 101 of the first to third LED stacks 23, 33 and 43 on a support substrate 51 in a pixel unit, and then connecting the first to third LED stacks to each other via interconnection lines.

[0330] FIG. 13 is a schematic cross-sectional view of a light emitting diode stack 102 for a display according to another exemplary embodiment of the present disclosure.

[0331] 13, a light-emitting diode stack 102 according to this illustrative embodiment is generally similar to the light-emitting diode stack 100 described with reference to FIG. 1, except that the second substrate 31 and the third substrate 41 are removed. The second substrate 31 and the third substrate 41 are used as growth substrates for the second LED stack 33 and the third LED stack 43, respectively, and are then removed from the second LED stack 33 and the third LED stack 43. Each of the second LED stack 33 and the third LED stack 43 is grown on a homogeneous GaN-based substrate, thereby providing a reduced dislocation density of 10 to 10 / cm.

[0332] Since the second substrate 31 and the third substrate 41 are removed, the interconnection lines electrically connected to these substrates 31 and 41 are electrically connected to the second LED stack 33 and the third LED stack 43, respectively. In addition, a roughened surface 41 a is formed on the top surface of the third LED stack 43.

[0333] FIG. 14 is a schematic cross-sectional view of a light-emitting diode stack 103 for a display according to yet another exemplary embodiment of the present disclosure.

[0334] 14, a light-emitting diode stack 103 according to this illustrative embodiment is generally similar to the light-emitting diode stack 101 described with reference to FIG. 11, except that the second substrate 31 and the third substrate 41 are removed. The second substrate 31 and the third substrate 41 are used as growth substrates for the second LED stack 33 and the third LED stack 43, respectively, and are then removed from the second LED stack 33 and the third LED stack 43. Each of the second LED stack 33 and the third LED stack 43 is grown on a homogeneous GaN-based substrate, thereby providing a reduced dislocation density of 10 to 10 / cm.

[0335] Since the second substrate 31 and the third substrate 41 are removed, the interconnection lines electrically connected to these substrates 31 and 41 are electrically connected to the second LED stack 33 and the third LED stack 43, respectively. In addition, a roughened surface 41 a is formed on the top surface of the third LED stack 43.

[0336] According to the exemplary embodiment, display light-emitting diode stacks 100, 101, 102, and 103 can be used to form multiple pixels at the wafer level, eliminating the need to individually package light-emitting diodes. Additionally, the light-emitting diode stack according to the exemplary embodiment has a structure in which first to third LED stacks 23, 33, and 43 are vertically stacked, thereby securing an area for subpixels within a limited pixel area. Furthermore, the light-emitting diode stack according to the exemplary embodiment allows light generated from the first LED stack 23, the second LED stack 33, and the third LED stack 43 to be emitted to the outside, thereby reducing light loss. Furthermore, each of the second LED stack 33 and the third LED stack 43 is grown on a homogeneous substrate, thereby reducing the dislocation density and improving light-emitting efficiency. Furthermore, the second substrate 31 and the third substrate 41 can remain on the second LED stack 33 and the third LED stack 43 without being removed, thereby simplifying the process of manufacturing the light-emitting diode stack.

[0337] FIG. 15 is a cross-sectional view illustrating a light-emitting stack structure according to an exemplary embodiment of the present disclosure.

[0338] 15, a light emitting stack according to an exemplary embodiment of the present disclosure includes multiple epitaxial stacks stacked on top of each other. The epitaxial stacks are disposed on a substrate 210.

[0339] The substrate 210 has a plate shape provided with a front surface and a rear surface.

[0340] The substrate 210 may have various shapes, each of which provides a front surface on which the epitaxial stacks are mounted. The substrate 210 may include an insulating material. The substrate 210 may be made of, but is not limited to, glass, quartz, silicon, an organic polymer, or an organic-inorganic composite material. That is, the material of the substrate 210 should not be particularly limited as long as it has insulating properties. In an exemplary embodiment of the present disclosure, a line portion may be further disposed on the substrate 210 to apply a light-emitting signal and a common voltage to each epitaxial stack. In particular, if each epitaxial stack operates using an active matrix method, a driving device including a thin film transistor may be further disposed on the substrate in addition to the line portion. For this purpose, the substrate 210 may be provided as a printed circuit board or a composite substrate obtained by forming the line portion and / or the driving device on glass, quartz, silicon, an organic polymer, or an organic-inorganic composite material.

[0341] The epitaxial stack is deposited in sequence on the front side of the substrate 210 .

[0342] In an exemplary embodiment of the present disclosure, two or more epitaxial stacks are provided, and the epitaxial stacks emit light having different wavelength bands from each other. That is, a plurality of epitaxial stacks are provided, and the epitaxial stacks have different energy bands from each other. In this exemplary embodiment, three epitaxial stacks are shown stacked in sequence on the substrate 210. In the following examples, the three layers stacked in sequence on the substrate 210 are referred to as first, second, and third epitaxial stacks 220, 230, and 240, respectively.

[0343] Each epitaxial stack can emit colored light in the visible light band among various wavelength bands. The light emitted from the lowest epitaxial stack is colored light with the longest wavelength and the lowest energy band, and the wavelengths of the colored light emitted from the epitaxial stacks gradually decrease from the bottom to the top of the epitaxial stack. The light emitted from the highest epitaxial stack is colored light with the shortest wavelength and the highest energy band. For example, the first epitaxial stack 220 emits a first colored light L1, the second epitaxial stack 230 emits a second colored light L2, and the third epitaxial stack 240 emits a third colored light L3. The first, second, and third colored lights L1, L2, and L3 may be different colors, or may have different wavelength bands that decrease in order. That is, the first, second and third colored lights L1, L2 and L3 may have different wavelength bands, and the colored lights may have progressively shorter wavelength bands with progressively higher energies from the first colored light L1 to the third colored light L3.

[0344] In this exemplary embodiment, the first color light L1 may be red light, the second color light L2 may be green light, and the third color light L3 may be blue light.

[0345] Each epitaxial stack emits light in the direction of the front surface of the substrate 210. In this case, light emitted from one epitaxial stack passes through other epitaxial stacks located on the optical path of the light emitted from that epitaxial stack before traveling in the direction of the front surface of the substrate 210. The direction of the front surface of the substrate 210 indicates the direction in which the first, second, and third epitaxial stacks 220, 230, and 240 are stacked.

[0346] Hereinafter, for convenience of explanation, the direction toward the front surface of the substrate 210 will be referred to as the "front direction" or "upward direction," and the direction toward the rear surface of the substrate 210 will be referred to as the "rear direction" or "downward direction." However, the terms "upward" and "downward" indicate directions relative to each other and may vary depending on the arrangement or stacking direction of the light emitting stack structure.

[0347] Each epitaxial stack emits light upward and transmits most of the light emitted from the epitaxial stack located below it. That is, light emitted from the first epitaxial stack 220 travels toward the front after passing through the second epitaxial stack 230 and the third epitaxial stack 240, and light emitted from the second epitaxial stack 230 travels toward the front after passing through the third epitaxial stack 240. For this reason, at least a portion, preferably the entire portion, of the epitaxial stacks other than the bottommost epitaxial stack is formed of an optically transparent material. The term "optically transparent material" refers not only to a material that transmits all light, but also to a material that transmits light having a predetermined wavelength or a portion of light having a predetermined wavelength. In an exemplary embodiment, each epitaxial stack can transmit at least about 60% of the light from the epitaxial stack located below it. According to other embodiments, each epitaxial stack can transmit greater than about 80% of the light from the epitaxial stack located below it, and according to other embodiments, each epitaxial stack can transmit greater than about 90% of the light from the epitaxial stack located below it.

[0348] In the light emitting stack structure having the above structure according to the exemplary embodiment of the present disclosure, the epitaxial stacks can be independently driven because signal lines that apply light emitting signals to the epitaxial stacks are independently connected to the epitaxial stacks, and various colors can be displayed depending on the light emitted from each epitaxial stack. In addition, because the epitaxial stacks that emit light having different wavelengths are formed to overlap each other, the light emitting stack structure can be formed within a small area.

[0349] 16 is a cross-sectional view showing a light-emitting stack structure according to an exemplary embodiment of the present disclosure having a line portion that allows each epitaxial stack to be driven independently. 17A to 17C are cross-sectional views showing details of each epitaxial stack in FIG. 16.

[0350] Referring to FIG. 16, the light-emitting stack structure includes a light-emitting area EA and a peripheral area PA disposed adjacent to the light-emitting area EA.

[0351] The light emitting areas EA are areas where light is emitted upward from the first, second and third epitaxial stacks 220, 230 and 240. The light emitting areas EA of the first, second and third epitaxial stacks 220, 230 and 240 overlap each other, so that the light emitting areas EA of the first, second and third epitaxial stacks 220, 230 and 240 have the same area as each other.

[0352] The peripheral area PA is an area where line portions connected to the first, second, and third epitaxial stacks 220, 230, and 240 are arranged. Light is emitted from the first, second, and third epitaxial stacks 220, 230, and 240 arranged in the peripheral area PA. However, although not shown, various additional components may be arranged in the peripheral area PA in addition to the line portions, and a separate blocking layer or reflective layer that prevents light from emitting to the outside may also be arranged in the peripheral area PA. Therefore, light does not exit through the peripheral area PA.

[0353] The first, second, and third epitaxial stacks 220, 230, and 240 are disposed on the substrate 210, with corresponding adhesive layers among the first, second, and third adhesive layers 250a, 250b, and 250c interposed therebetween. The first, second, and third adhesive layers 250a, 250b, and 250c may include a non-conductive material and a light-transmitting material. For example, the first, second, and third adhesive layers 250a, 250b, and 250c may include an optically clear adhesive (OCA). The materials of the first, second, and third adhesive layers 250a, 250b, and 250c are not particularly limited as long as they are optically transparent and stably bonded to the respective epitaxial stacks. For example, the first, second, and third adhesive layers 250a, 250b, and 250c can include organic materials such as SU-8, various resists, parylene, epoxy-based polymers such as poly(methyl methacrylate) (PMMA) and benzocyclobutene (BCB), and inorganic materials such as silicon oxide, aluminum oxide, and fused glass. Conductive oxides can also be used as adhesive layers, if necessary, provided they are insulated from other components. When organic materials or inorganic materials such as fused glass are used as adhesive layers, the first, second, and third epitaxial stacks 220, 230, and 240 and the substrate 210 are bonded together by coating the adhesive sides of the first, second, and third epitaxial stacks 220, 230, and 240 and the substrate 210 with the materials and then applying high temperature and pressure to the materials under high vacuum. When an inorganic material (excluding molten glass) is used as the adhesive layer, the first, second, and third epitaxial stacks 220, 230, and 240 and the substrate 210 are bonded together by depositing the material on the adhesive side of the first, second, and third epitaxial stacks 220, 230, and 240 and the substrate 210, planarizing the material using chemical mechanical planarization (CMP), performing a plasma treatment on the surfaces of the material, and bonding under high vacuum.

[0354] 17A to 17C, first, second, and third epitaxial stacks 220, 230, and 240 include, in order, first semiconductor layers 221, 231, and 241, active layers 223, 233, and 243, and second semiconductor layers 225, 235, and 245. It should be noted that, although the first semiconductor layers 221, 231, and 241, the active layers 223, 233, and 243, and the second semiconductor layers 225, 235, and 245 are stacked in an upward direction in FIGS. 17A to 17C, the first, second, and third epitaxial stacks 220, 230, and 240 in FIGS. 17A to 17C are shown in reverse in FIG. That is, the first, second and third epitaxial stacks 220, 230 and 240 shown in FIG. 16 are arranged in the order of second semiconductor layers 225, 235 and 245, active layers 223, 233 and 243 and first semiconductor layers 221, 231 and 241 from top to bottom.

[0355] 17A, the first semiconductor layer 221, the active layer 223, and the second semiconductor layer 225 of the first epitaxial stack 220 may include a semiconductor material that emits red light. Examples of semiconductor materials that emit red light include aluminum gallium arsenide (AlGaAs), gallium arsenide phosphide (GaAsP), aluminum gallium indium phosphide (AlGaInP), and gallium phosphide (GaP). However, the semiconductor material that emits red light should not be limited to these or other materials, and various other materials may be used.

[0356] The first semiconductor layer 221 may be a semiconductor layer containing first-conductivity-type impurities, and the second semiconductor layer 225 may be a semiconductor layer containing second-conductivity-type impurities. The first and second conductivity types have opposite polarities. When the first conductivity type is n-type, the second conductivity type is p-type, and when the first conductivity type is p-type, the second conductivity type is n-type. In the exemplary embodiment of the present disclosure, a structure in which an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are formed in this order will be described as a representative example. The first semiconductor layer 221 may be referred to as an "n-type semiconductor layer," and the second semiconductor layer 225 may be referred to as a "p-type semiconductor layer." This is for convenience of explanation; in other embodiments of the present disclosure, the first semiconductor layer 221 and the second semiconductor layer 225 may be p-type and n-type semiconductor layers, respectively.

[0357] A mesa is formed in the first epitaxial stack 220 by removing portions of the n-type semiconductor layer 221, the active layer 223, and the p-type semiconductor layer 225. A first n-type contact electrode 229 is disposed on the exposed upper surface of the n-type semiconductor layer 221, and a first p-type contact electrode 227 is disposed on the p-type semiconductor layer 225 in which the mesa is formed.

[0358] The first n-type contact electrode 229 and the first p-type contact electrode 227 may have a single-layer structure or a multi-layer structure of a metal material. For example, the first n-type contact electrode 229 and the first p-type contact electrode 227 may include a metal material such as Al, Ti, Cr, Au, Ag, Ti, Sn, Ni, Cr, W, Cu, or an alloy thereof. In particular, the first p-type contact electrode 227 may include a metal material with high reflectivity, which can improve the upward light-emitting efficiency of light emitted from the first epitaxial stack 220.

[0359] The first epitaxial stack 220 is inverted and disposed on the substrate 210 with the first adhesive layer 250a interposed therebetween, so that the first n-type contact electrode 229 and the first p-type contact electrode 227 are disposed between the substrate 210 and the second adhesive layer 250b. The first p-type contact electrode 227 overlaps the light emitting area EA and reflects light emitted from the active layer 223 of the first epitaxial stack 220 upward.

[0360] 17B, ​​the second epitaxial stack 230 includes an n-type semiconductor layer 231, an active layer 233, and a p-type semiconductor layer 235, which are stacked in this order. The n-type semiconductor layer 231, the active layer 233, and the p-type semiconductor layer 235 may include a semiconductor material that emits green light. Examples of semiconductor materials that emit green light include indium gallium nitride (InGaN), gallium nitride (GaN), gallium phosphide (GaP), aluminum gallium indium phosphide (AlGaInP), and aluminum gallium phosphide (AlGaP). However, the semiconductor material that emits green light should not be limited to these, and various other materials may be used.

[0361] 16, the second p-type contact electrode 237 is disposed on the p-type semiconductor layer 235 of the second epitaxial stack 230. In FIG. 16, the second epitaxial stack 230 corresponds to the inverted second epitaxial stack 230 of FIG. 17B, so the second p-type contact electrode 237 is disposed between the first epitaxial stack 220 and the second epitaxial stack 230, specifically, between the second adhesion layer 250b and the second epitaxial stack 230.

[0362] The second p-type contact electrode 237 may include a transparent conductive material, for example, a transparent conductive oxide (TCO), and may have a thickness of about 2000 angstroms to about 2 micrometers.

[0363] 17C, the third epitaxial stack 240 includes an n-type semiconductor layer 241, an active layer 243, and a p-type semiconductor layer 245, which are stacked in this order. The n-type semiconductor layer 241, the active layer 243, and the p-type semiconductor layer 245 may include a semiconductor material that emits blue light. Examples of the semiconductor material that emits blue light include gallium nitride (GaN), indium gallium nitride (InGaN), and zinc selenide (ZnSe). However, the semiconductor material that emits blue light should not be limited thereto, and various other materials may be used.

[0364] 16 again, the third p-type contact electrode 247 is disposed on the p-type semiconductor layer 245 of the third epitaxial stack 240. In FIG. 16, the third epitaxial stack 240 corresponds to the inverted third epitaxial stack 240 of FIG. 17C, so the third p-type contact electrode 247 is disposed between the second epitaxial stack 230 and the third epitaxial stack 240, specifically, between the third adhesion layer 250c and the third epitaxial stack 240.

[0365] In this illustrative example, the n-type semiconductor layers 221, 231, and 241 and the p-type semiconductor layers 225, 235, and 245 of the first, second, and third epitaxial stacks 220, 230, and 240, respectively, have a single-layer structure, but depending on the embodiment, the n-type semiconductor layers 221, 231, and 241 and the p-type semiconductor layers 225, 235, and 245 of the first, second, and third epitaxial stacks 220, 230, and 240, respectively, may have a multi-layer structure and may include a superlattice layer. The active layers 223, 233, and 243 of the first, second, and third epitaxial stacks 220, 230, and 240 may have a single quantum well structure or a multiple quantum well structure.

[0366] In this exemplary embodiment, the second and third p-type contact electrodes 237 and 247 are disposed to overlap the light emitting area EA. The second and third p-type contact electrodes 237 and 247 may comprise a transparent conductive material to transmit light from the underlying epitaxial stack. For example, each of the second and third p-type contact electrodes 237 and 247 may comprise a transparent conductive oxide (TCO). Transparent conductive oxides include tin oxide (SnO), indium oxide (InO), zinc oxide (ZnO), and the like. The transparent conductive oxide can include indium tin oxide (ITO) and indium tin zinc oxide (ITZO). The transparent conductive oxide can be deposited by chemical vapor deposition (CVD) or physical vapor deposition (PVD) using an evaporator or sputtering. The second and third p-type contact electrodes 237 and 247 can have a thickness sufficient to function as an etching stopper in the following manufacturing process while maintaining a satisfactory transmittance.

[0367] In this exemplary embodiment, the first, second, and third p-type contact electrodes 227, 237, and 247 are connected to a common line. The common line is a line to which a common voltage is applied. Furthermore, a common signal line is connected to the first n-type contact electrode 229 and the p-type semiconductor layers 235 and 245 of the second and third epitaxial stacks 230 and 240, respectively. In this exemplary embodiment, a common voltage Sc is applied to the first p-type contact electrode 227, the second p-type contact electrode 237, and the third p-type contact electrode 247 via the common line, and an emission signal is applied to the first n-type contact electrode 229, the n-type semiconductor layer 231 of the second epitaxial stack 230, and the n-type semiconductor layer 241 of the third epitaxial stack 240 via an emission signal line. Thus, the emission of light from the first, second, and third epitaxial stacks 220, 230, and 240 is controlled. The light emission signals include first, second and third light emission signals SR, SG and SB corresponding to the first, second and third epitaxial stacks 220, 230 and 240, respectively, and the first, second and third light emission signals SR, SG and SB are signals corresponding to the emission of red light, green light and blue light, respectively.

[0368] In the above-described embodiment, a common voltage is applied to the p-type semiconductor layers of the first, second, and third epitaxial stacks 220, 230, and 240, and an optical emission signal is applied to the n-type semiconductor layers of the first, second, and third epitaxial stacks 220, 230, and 240, but the embodiments of the present disclosure should not be limited thereto. According to other embodiments of the present disclosure, a common voltage may be applied to the n-type semiconductor layers of the first, second, and third epitaxial stacks 220, 230, and 240, and an optical emission signal may be applied to the p-type semiconductor layers of the first, second, and third epitaxial stacks 220, 230, and 240. This structure can be easily realized by forming each epitaxial stack in the order of a p-type semiconductor layer, an active layer, and an n-type semiconductor layer, which is different from the stacking order of the epitaxial stacks formed in the above-described embodiment, in which an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are formed in this order. In the above-described embodiment, the first, second, and third epitaxial stacks 220, 230, and 240 are driven in response to light-emitting signals applied thereto. That is, the first epitaxial stack 220 is driven in response to the first light-emitting signal SR, the second epitaxial stack 230 is driven in response to the second light-emitting signal SG, and the third epitaxial stack 240 is driven in response to the third light-emitting signal SB. In this case, the first, second, and third light-emitting signals SR, SG, and SB are applied independently to the first, second, and third epitaxial stacks 220, 230, and 220, respectively. As a result, the first, second, and third epitaxial stacks 220, 230, and 240 are independently driven. The light-emitting stacked structure can provide light of various hues by combining the first, second, and third color lights emitted upward from the first, second, and third epitaxial stacks.

[0369] When displaying colors, the light-emitting stack structure having the above-described structure provides different color lights through overlapping areas rather than through different areas on a plane, thereby enabling miniaturization and integration of light-emitting elements. According to the prior art, light-emitting elements emitting different color lights, e.g., red, green, and blue light, are spaced apart on a plane to achieve a full-color display. Therefore, since the light-emitting elements are spaced apart on a plane, the area occupied by the light-emitting elements in the prior art is relatively large. In contrast, according to the present disclosure, light-emitting elements emitting different color lights are arranged overlapping each other within the same area to form a light-emitting stack structure, thereby enabling a full-color display to be achieved in a significantly smaller area than the prior art. Therefore, a high-resolution display device can be manufactured within a small area.

[0370] Furthermore, even in the case of conventional light-emitting devices manufactured using a stacking method, the conventional light-emitting devices are manufactured by individually forming contact portions within each light-emitting element, for example, by separately forming light-emitting elements and connecting the light-emitting elements to each other using wiring. As a result, the structure of the light-emitting device is complex and difficult to manufacture. However, the light-emitting stack structure according to the exemplary embodiment of the present disclosure is manufactured by sequentially stacking multiple epitaxial stacks on a single substrate, forming contact portions within the epitaxial stacks with minimal steps, and connecting line portions to the epitaxial stacks. In addition, according to the exemplary embodiment of the present disclosure, since a single light-emitting stack structure is implemented instead of conventional light-emitting elements, the manufacturing method of the display device can be simplified compared to the conventional manufacturing method of a display device in which light-emitting elements of individual colors are separately manufactured and then individually mounted.

[0371] The light emitting stack structure according to the exemplary embodiments of the present disclosure may additionally include various components for providing colored light with high purity and high efficiency. For example, the light emitting stack structure according to the exemplary embodiments of the present disclosure may include a wavelength pass filter for preventing light having a relatively short wavelength from traveling to an epitaxial stack emitting light having a relatively long wavelength.

[0372] In the following embodiments, to avoid duplication, features different from those of the above-described embodiments will be mainly described, and parts not described will be assumed to be the same or similar to those of the above-described embodiments.

[0373] FIG. 18 is a cross-sectional view illustrating a light-emitting stack having a predetermined wavelength pass filter according to an exemplary embodiment of the present disclosure.

[0374] Referring to FIG. 18, a light emitting stack according to an exemplary embodiment of the present disclosure can include a first wavelength pass filter 261 disposed between the first epitaxial stack 220 and the second epitaxial stack 230 .

[0375] The first wavelength pass filter 261 selectively transmits light having a predetermined wavelength. The first wavelength pass filter 261 can transmit the first color light emitted from the first epitaxial stack 220 and can block or reflect light other than the first color light. Therefore, the first color light emitted from the first epitaxial stack 220 can travel upward, and the second and third color lights emitted from the second and third epitaxial stacks 230 and 240, respectively, do not travel toward the first epitaxial stack 220, but can be reflected or blocked by the first wavelength pass filter 261.

[0376] The second and third color lights have shorter wavelengths and higher energies than the first color light. When the second and third color lights are incident on the first epitaxial stack 220, additional light emission may be stimulated in the first epitaxial stack 220. In this exemplary embodiment, the second and third color lights can be prevented from entering the first epitaxial stack 220 by the first wavelength pass filter 261.

[0377] In an exemplary embodiment of the present disclosure, a second wavelength pass filter 263 is disposed between the second epitaxial stack 230 and the third epitaxial stack 240. The second wavelength pass filter 263 can transmit the first and second color lights emitted from the first and second epitaxial stacks 220 and 230, respectively, and can block or reflect light other than the first and second color lights. Therefore, the first and second color lights emitted from the first and second epitaxial stacks 220 and 230, respectively, can travel upward, and the third color light emitted from the third epitaxial stack 240 does not travel toward the first and second epitaxial stacks 220 and 230, or can be reflected or blocked by the second wavelength pass filter 263.

[0378] Similar to the above description, the third color light has a shorter wavelength and higher energy than the first and second color lights. When the third color light is incident on the first and second epitaxial stacks 220 and 230, additional light emission may be guided within the first and second epitaxial stacks 220 and 230. In this exemplary embodiment, the third color light can be prevented from entering the first and second epitaxial stacks 220 and 230 by the second wavelength pass filter 263.

[0379] The light emitting stack structure according to the exemplary embodiment of the present disclosure may further include various components to provide highly efficient and uniform light. For example, the light emitting stack structure according to the exemplary embodiment of the present disclosure may include various uneven portions on the light emitting surface.

[0380] 19 and 20 are cross-sectional views illustrating light emitting stack structures having textured portions formed in at least a portion of the epitaxial stack according to exemplary embodiments of the present disclosure.

[0381] A light-emitting stack structure according to an exemplary embodiment of the present disclosure may include a textured portion PR formed on the upper surface of at least one of the n-type semiconductor layers 221, 231, and 241 of the first, second, and third epitaxial stacks 220, 230, and 240. In an exemplary embodiment of the present disclosure, the textured portion PR of each epitaxial stack may be selectively formed. For example, the textured portion PR may be disposed on the first and third epitaxial stacks 220 and 240 as shown in FIG. 19 , and the textured portion PR may be disposed on the first, second, and third epitaxial stacks 220, 230, and 240 as shown in FIG. 20 . The textured portion PR of each epitaxial stack is disposed on the n-type semiconductor layers 221, 231, and 241 corresponding to the light-emitting surfaces of the first, second, and third epitaxial stacks 220, 230, and 240, respectively.

[0382] The uneven portion PR is used to improve light emission efficiency. The uneven portion PR can be provided in various shapes, such as polygonal pyramids, hemispheres, or roughened surfaces, on which the uneven portions are randomly arranged. The uneven portion PR can be formed using a sapphire substrate that has been textured or patterned by various etching processes.

[0383] In an exemplary embodiment of the present disclosure, the first, second, and third color lights from the first, second, and third epitaxial stacks 220, 230, and 240 may have differences in luminous intensity, which may lead to differences in visibility. In this exemplary embodiment, the luminous efficiency can be improved by selectively forming textured portions PR on the light-emitting surfaces of the first, second, and third epitaxial stacks 220, 230, and 240, thereby reducing the difference in luminous intensity between the first, second, and third color lights. Because color lights corresponding to red and / or blue have lower visibility than color lights corresponding to green, the difference in visibility can be reduced by texturing the first epitaxial stack 220 and / or the third epitaxial stack 240. In particular, red light has a relatively lower luminous intensity because it is provided from the lowest portion of the light-emitting stack. In this case, when the uneven portion PR is formed on the first epitaxial stack 220, the light efficiency can be improved.

[0384] The light emitting stack structure having the above-described structure corresponds to a light emitting element capable of displaying various colors and can be used as a pixel in a display device. In the following description, a display device using the light emitting stack structure having the above-described structure as its component will be described.

[0385] FIG. 21 is a plan view showing a display device 2100 according to an exemplary embodiment of the present disclosure, and FIG. 22 is an enlarged plan view showing a portion P1 of FIG.

[0386] 21 and 22, a display device 2100 according to an exemplary embodiment of the present disclosure displays any visual information such as text, video, photographs, and two-dimensional or three-dimensional images.

[0387] The display device 2100 can have a variety of shapes, such as a closed polygon with straight sides, such as a rectangle, a circle or ellipse with curved sides, and a semicircle or semi-ellipse with straight and curved sides. In the exemplary embodiment of the present disclosure, a display device having a rectangular shape is shown.

[0388] The display device 2100 includes a plurality of pixels 2110 for displaying an image. Each pixel 2110 is the smallest unit for displaying an image. Each pixel 2110 may include a light-emitting stack structure having the structure described above and may emit white light and / or colored light.

[0389] In an exemplary embodiment of the present disclosure, each pixel 2110 includes a first subpixel 2110R that emits red light, a second subpixel 2110G that emits green light, and a third subpixel 2110B that emits blue light. The first, second, and third subpixels 2110R, 2110G, and 2110B may correspond to the first, second, and third epitaxial stacks 220, 230, and 240, respectively, of the light-emitting stack structure described above.

[0390] The pixels 2110 are arranged in a matrix. The expression that the pixels 2110 are arranged in a matrix can indicate that the pixels 2110 are not only arranged in a precise line along rows or columns, but also that the pixels 2110 are generally arranged along rows or columns while the detailed positions of the pixels 2110 vary, for example, in a zigzag manner.

[0391] FIG. 23 is a block diagram illustrating a display device according to an exemplary embodiment of the present disclosure.

[0392] 23, a display device 2100 according to an exemplary embodiment of the present disclosure includes a timing controller 2350, a scan driver 2310, a data driver 2330, a line unit, and pixels. When each pixel includes multiple sub-pixels, each sub-pixel is individually connected to the scan driver 2310 and the data driver 2330 via the line unit.

[0393] The timing controller 2350 receives various control signals and image data required to drive the display device 2100 from an external source (e.g., a system that transmits image data). The timing controller 2350 rearranges the received image data and applies the rearranged image data to the data driver 2330. The timing controller 2350 also generates scan control signals and data control signals required to drive the scan driver 2310 and the data driver 2330, and applies the generated scan control signals and data control signals to the scan driver 2310 and the data driver 2330, respectively.

[0394] The scan driver 2310 receives a scan control signal from the timing controller 2350 and generates a scan signal in response to the scan control signal.

[0395] The data driver 2330 receives data control signals and image data from the timing controller 2350, and generates data signals in response to the data control signals.

[0396] The line section includes a plurality of signal lines. Specifically, the line section includes scan lines 2130 connecting the scan driver 2310 and the sub-pixels, and data lines 2120 connecting the data driver 2330 and the sub-pixels. The scan lines 2130 are connected to the sub-pixels, respectively, and the scan lines connected to the sub-pixels, respectively, are shown as first, second, and third sub-scan lines 2130R, 2130G, and 2130B.

[0397] In addition, the line section may further include lines connecting the timing controller 2350 and the scan driver 2310, the timing controller 2350 and the data driver 2330, or other components to each other for transmitting signals.

[0398] The scan lines 2130 apply scan signals generated by the scan driver 2310 to the sub-pixels. The data signals generated by the data driver 2330 are applied to the data lines 2120.

[0399] The sub-pixels are connected to scan lines 2130 and data lines 2120. The sub-pixels selectively emit light in response to data signals provided from data lines 2120 when scan signals from scan lines 2130 are applied thereto. As an example, each sub-pixel emits light at a brightness corresponding to the data signal applied thereto in each frame period. A sub-pixel to which a data signal corresponding to black brightness is applied does not emit light in that frame period, and therefore black is displayed.

[0400] In exemplary embodiments of the present disclosure, the sub-pixels can be driven in a passive or active matrix manner. When the display device is driven in an active matrix manner, the display device 2100 can be driven by additionally receiving first and second pixel power supplies in addition to the scan signal and the data signal.

[0401] 24 is a circuit diagram showing one subpixel for a passive matrix type display device, where the subpixel may be one of a red subpixel, a green subpixel, and a blue subpixel, and a first subpixel 2110R is shown in this exemplary embodiment.

[0402] 24, the first subpixel 2110R includes a light emitting element 2150 connected between the scan line 2130 and the data line 2120. The light emitting element 2150 corresponds to the first epitaxial stack 220. When a voltage equal to or greater than a threshold voltage is applied between the p-type semiconductor layer and the n-type semiconductor layer, the first epitaxial stack 220 emits light with a brightness corresponding to the level of the voltage applied thereto. That is, the light emission of the first subpixel 2110R can be controlled by controlling the voltage of the scan signal applied to the scan line 2130 and / or the voltage of the data signal applied to the data line 2120.

[0403] 25 is a circuit diagram showing a first sub-pixel 2110R for an active matrix type display device. When the display device is an active matrix type display device, the first sub-pixel 2110R can be driven by further receiving first and second pixel power supplies ELVDD and ELVSS in addition to the scan signal and the data signal.

[0404] Referring to FIG. 25, the first subpixel 2110R includes one or more light-emitting elements 2150 and a transistor portion connected to the light-emitting elements 2150.

[0405] The light emitting element 2150 may correspond to the first epitaxial stack 220, and a p-type semiconductor layer of the light emitting element 2150 is connected to a first pixel power supply ELVDD via a transistor unit, and an n-type semiconductor layer of the light emitting element 2150 is connected to a second pixel power supply ELVSS. The first pixel power supply ELVDD and the second pixel power supply ELVSS may have different potentials. For example, the second pixel power supply ELVSS may have a potential lower than the potential of the first pixel power supply ELVDD by an amount equal to or greater than the threshold voltage of the light emitting element 2150. Each light emitting element 2150 emits light at a brightness corresponding to a driving current controlled by the transistor unit.

[0406] According to an exemplary embodiment of the present disclosure, the transistor portion includes first and second transistors M1 and M2 and a storage capacitor Cst, but the configuration of the transistor portion should not be limited to the embodiment shown in FIG.

[0407] The first transistor (switching transistor) M1 includes a source electrode connected to the data line 2120, a drain electrode connected to the first node N1, and a gate electrode connected to the scan line 2130. When a scan signal having a voltage sufficient to turn on the first transistor M1 is provided via the scan line 2130, the first transistor M1 is turned on to electrically connect the data line 2120 and the first node N1. In this case, the data signal for the frame is applied to the data line 2120, and therefore the data signal is applied to the first node N1. The storage capacitor Cst is charged by the data signal applied to the first node N1.

[0408] The second transistor (driving transistor) M2 includes a source electrode connected to the first pixel power supply ELVDD, a drain electrode connected to the n-type semiconductor layer of the light emitting element 2150, and a gate electrode connected to the first node N1. The second transistor M2 controls the amount of driving current supplied to the light emitting element 2150 in response to the voltage of the first node N1.

[0409] One electrode of the storage capacitor Cst is connected to the first pixel power supply ELVDD, and the other electrode of the storage capacitor Cst is connected to the first node N1. The storage capacitor Cst is charged to a voltage corresponding to the data signal applied to the first node N1 and holds the charged voltage until the data signal of the next frame is provided.

[0410] For convenience of explanation, FIG. 25 illustrates a transistor portion including two transistors. However, the number of transistors included in the transistor portion should not be limited to two, and the configuration of the transistor portion can be changed in various ways. For example, the transistor portion can include more transistors and more capacitors. In addition, in this exemplary embodiment, the configurations of the first and second transistors, storage capacitors, and lines are not shown in detail, but the first and second transistors, storage capacitors, and lines can be changed in various ways within the scope of realizing a circuit according to an exemplary embodiment of the present disclosure.

[0411] The above-described pixels can be varied in a variety of ways within the scope of this disclosure and can be realized with the following structures:

[0412] FIG. 26 is a plan view showing a pixel according to an exemplary embodiment of the present disclosure, and FIGS. 27A and 27B are cross-sectional views taken along lines II' and II-II' in FIG. 26, respectively.

[0413] 26, 27A, and 27B, a pixel according to an exemplary embodiment of the present disclosure includes a light-emitting area EA and a peripheral area PA. An epitaxial stack is stacked within the light-emitting area EA. In this exemplary embodiment, the epitaxial stack includes first, second, and third epitaxial stacks 220, 230, and 240.

[0414] The first, second, and third epitaxial stacks 220, 230, and 240 are connected to the first, second, and third sub-scan lines 2130R, 2130G, and 2130B and the data line 2120. In an exemplary embodiment of the present disclosure, the first, second, and third sub-scan lines 2130R, 2130G, and 2130B may extend in a first direction, for example, the horizontal direction in FIG. 26 . The data line 2120 is connected to the first p-type contact electrode 227 through the first contact hole CH1, and the first p-type contact electrode 227 essentially functions as the data line 2120. Therefore, hereinafter, the first p-type contact electrode 227 may be referred to as the data line 2120. The data line 2120 may extend in a second direction, for example, the vertical direction in FIG. 26 across the first, second, and third sub-scan lines 2130R, 2130G, and 2130B. However, the extending directions of the first, second and third sub-scan lines 2130R, 2130G and 2130B and the data lines 2120 should not be limited to this or thereto, and can be changed in various ways according to the arrangement of pixels.

[0415] The first sub-scan line 2130R and the data line, specifically the first p-type contact electrode 227, are connected to the first epitaxial stack 220. The data line 2120 and the second sub-scan line 2130G are connected to the second epitaxial stack 230 through first and second contact holes CH1 and CH2, respectively. The data line 2120 and the third sub-scan line 2130B are connected to the third epitaxial stack 240 through first and second contact holes CH1 and CH2, respectively. In this illustrative embodiment, the first and second contact holes CH1 and CH2 are formed in the peripheral area PA.

[0416] Adhesion layers, contact electrodes, and wavelength pass filters are disposed between the substrate 210 and the first epitaxial stack 220, between the first epitaxial stack 220 and the second epitaxial stack 230, and between the second epitaxial stack 230 and the third epitaxial stack 240. Below, a pixel according to an exemplary embodiment of the present disclosure will be described according to the stacking order.

[0417] According to this exemplary embodiment, a first epitaxial stack 220 having a mesa structure is disposed on a substrate 210 with a first adhesion layer 250a interposed therebetween.

[0418] A first insulating layer 271 is disposed on the lower surface of the first epitaxial stack 220, i.e., the surface facing the substrate 210. The first insulating layer 271 is provided with a plurality of contact holes therethrough. A first n-type contact electrode 229, which contacts the n-type semiconductor layer of the first epitaxial stack 220, is disposed in the contact hole corresponding to the peripheral area PA, and a first p-type contact electrode 227, which contacts the p-type semiconductor layer of the first epitaxial stack 220, is disposed in the contact hole corresponding to the light emitting area EA. First and second ohmic electrodes 229′ and 227′ are disposed on the areas where the first n-type contact electrode 229 and the first p-type contact electrode 227 are to be formed, for ohmic contact with the first p-type contact electrode 227 and the first n-type contact electrode 229. The first and second ohmic electrodes 229′ and 227′ for ohmic contact may include various materials. In an exemplary embodiment of the present disclosure, the second ohmic electrode 227′ corresponding to the p-type ohmic electrode may include Au(Zn) or Au(Be). In this case, since the material for the second ohmic electrode 227′ has a lower reflectivity than Ag, Al, and Au, an additional reflective electrode may be disposed. Ag or Au may be used as the material for the additional reflective electrode, and a layer including Ti, Ni, Cr, or Ta may be disposed as an adhesion layer for adhesion to adjacent components. In this case, the adhesion layer is thinly deposited on the upper and lower surfaces of the reflective electrode including Ag or Au.

[0419] The first p-type contact electrode 227 overlaps the light emitting area EA and is provided to cover the entire light emitting area EA in a plan view. The first p-type contact electrode 227 includes a reflective material and can reflect light within the first epitaxial stack 220. In this case, the first insulating layer 271 is formed to have reflectivity so that light can be easily reflected within the first epitaxial stack 220. For example, the first insulating layer 271 may have an omni-directional reflector (ODR) structure.

[0420] A second insulating layer 273 is disposed between the first p-type contact electrode 227 and the substrate 210. The second insulating layer 273 covers the lower surface of the first epitaxial stack 220 on which the first p-type contact electrode 227 is formed, and has a contact hole passing therethrough with the first n-type contact electrode 229 exposed. The first sub-scan line 2130R is disposed between the second insulating layer 273 and the substrate 210 and applies a data signal to the first n-type contact electrode 229.

[0421] A second adhesive layer 250b is disposed on the first epitaxial stack 220, and a first wavelength pass filter 261, a second p-type contact electrode 237, and a second epitaxial stack 230 are disposed in this order on the second adhesive layer 250b. Although not separately shown, the second epitaxial stack 230 includes a p-type semiconductor layer, an active layer, and an n-type semiconductor layer, which are stacked in this order from the bottom of the second epitaxial stack 230 upward.

[0422] In this illustrative embodiment, the first wavelength pass filter 261 and the second p-type contact electrode 237 may have substantially the same area as the first epitaxial stack 220, and the second epitaxial stack 230 may have a smaller area than the first epitaxial stack 220. Because the second epitaxial stack 230 has a smaller area than the first epitaxial stack 220, a portion of the second p-type contact electrode 237 may be exposed.

[0423] A third adhesive layer 250c is disposed on the second epitaxial stack 230, and a second wavelength pass filter 263, a third p-type contact electrode 247, and a third epitaxial stack 240 are disposed in this order on the third adhesive layer 250c. Although not separately shown, the third epitaxial stack 240 includes a p-type semiconductor layer, an active layer, and an n-type semiconductor layer, which are stacked in this order from the bottom of the third epitaxial stack 240 upward.

[0424] The third epitaxial stack 240 may have a smaller area than the second epitaxial stack 230. The third epitaxial stack 240 may have a smaller area than the third p-type contact electrode 247, so that a portion of the upper surface of the third p-type contact electrode 247 may be exposed. In addition, the third p-type contact electrode 247 may have a smaller area than the second epitaxial stack 230, so that a portion of the upper surface of the second epitaxial stack 230 may be exposed.

[0425] A third insulating layer 275 is disposed on the third epitaxial stack 240 to cover the layered structure of the first, second, and third epitaxial stacks 220, 230, and 240. The third insulating layer 275 can include, but is not limited to, a variety of organic / inorganic insulating materials. For example, the third insulating layer 275 can include inorganic insulating materials including silicon nitride and silicon oxide, or organic insulating materials such as polyimide.

[0426] The third insulating layer 275 includes a first contact hole CH1 that penetrates the layer while exposing the upper surfaces of the first, second, and third p-type contact electrodes 227, 237, and 247, and a second contact hole CH2 that penetrates the layer while exposing the upper surfaces of the n-type semiconductor layers of the second and third epitaxial stacks 230 and 240.

[0427] The data line 2120 and the first, second, and third sub-scan lines 2130R, 2130G, and 2130B are disposed on the third insulating layer 275. The data line 2120 is simultaneously connected to the first, second, and third p-type contact electrodes 227, 237, and 247 through a first contact hole CH1 formed through the third insulating layer 275. The second and third sub-scan lines 2130G and 2130B are respectively connected to the n-type semiconductor layer of the second epitaxial stack 230 and the n-type semiconductor layer of the third epitaxial stack 240 through a second contact hole CH2.

[0428] In an exemplary embodiment of the present disclosure, the second sub-scan line 2130G is in direct contact with and electrically connected to the n-type semiconductor layer of the second epitaxial stack 230, and the third sub-scan line 2130B is in direct contact with and electrically connected to the n-type semiconductor layer of the third epitaxial stack 240. However, in other embodiments, a second n-type contact electrode may be further disposed between the second sub-scan line 2130G and the n-type semiconductor layer of the second epitaxial stack 230, and the second sub-scan line 2130G and the n-type semiconductor layer of the second epitaxial stack 230 may be electrically connected to each other by the second n-type contact electrode. In addition, a third n-type contact electrode may be further disposed between the third sub-scan line 2130B and the n-type semiconductor layer of the third epitaxial stack 240, and the third sub-scan line 2130B and the n-type semiconductor layer of the third epitaxial stack 240 may be electrically connected to each other by the third n-type contact electrode.

[0429] A fourth insulating layer 277 is disposed on the data line 2120 and the first, second, and third sub-scan lines 2130R, 2130G, and 2130B to cover the data line 2120 and the first, second, and third sub-scan lines 2130R, 2130G, and 2130B, and the fourth insulating layer 277 may include, but is not limited to, various organic / inorganic insulating materials.

[0430] Although not separately shown in this illustrative embodiment, uneven portions may be selectively disposed on the upper surfaces of the first, second, and third epitaxial stacks 220, 230, and 240, i.e., on the upper surfaces of the n-type semiconductor layers of the first, second, and third epitaxial stacks 220, 230, and 240. Each uneven portion may be disposed only within an area corresponding to the light emitting area EA, or may be disposed on the entire upper surface of each n-type semiconductor layer. Therefore, the second and third sub-scan lines 2130G and 2130B may be in contact with and electrically connected to an n-type semiconductor layer that the uneven portion PR does not have disposed thereon, or may be in contact with and electrically connected to an n-type semiconductor layer that the uneven portion PR has disposed thereon.

[0431] Although not shown in detail, in an exemplary embodiment of the present disclosure, an optically opaque layer may be further disposed on the fourth insulating layer 277 corresponding to the side surface of the pixel. The optically opaque layer may act as a light blocking layer to prevent light from the first, second, and third epitaxial stacks 220, 230, and 240 from exiting the side surface of the pixel, and may include a material that absorbs or reflects light.

[0432] The optically opaque layer should not be particularly limited as long as it absorbs or reflects light to block its transmission. In exemplary embodiments of the present disclosure, the optically opaque layer may be a distributed Bragg reflector (DBR) dielectric mirror, a metal reflective layer formed on an insulating layer, or a black organic polymer layer. When a metal reflective layer is used as the optically opaque layer, the metal reflective layer may be in a floating state, in which the metal reflective layer is electrically isolated from other pixel components.

[0433] Light-impermeable layers disposed on the sides of pixels can prevent light emitted from a particular pixel from affecting or mixing with light emitted from adjacent pixels.

[0434] A pixel having the above structure can be manufactured by sequentially stacking first, second, and third epitaxial stacks on a substrate, and will be described in detail below with reference to FIG. 28 and FIGS. 29A to 29L.

[0435] Figure 28 is a plan view showing a substrate on which the first to third epitaxial stacks are stacked, and Figures 29A to 29L are cross-sectional views taken along line II' in Figure 28 showing the steps of stacking the first to third epitaxial stacks on the substrate in sequence.

[0436] 28 and 29A, a first epitaxial stack 220 is formed on a first initial substrate 210p. In an exemplary embodiment of the present disclosure, the first initial substrate 210p may be made of a semiconductor, such as gallium arsenide (GaAs), required to form the first epitaxial stack 220. The first epitaxial stack 220 is manufactured by forming an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on the first initial substrate 210p, and removing portions of the n-type semiconductor layer, the active layer, and the p-type semiconductor layer to form a mesa structure.

[0437] 28 and 29B, a first insulating layer 271 is formed on a first initial substrate 210p, and contact holes are formed through the first insulating layer 271 to partially expose the p-type semiconductor layer and the n-type semiconductor layer. A plurality of contact holes may be provided on the upper part of the p-type semiconductor layer. Ohmic electrodes 227' and 229' are formed on the p-type semiconductor layer and the n-type semiconductor layer exposed through the contact holes, respectively.

[0438] 28 and 29C, a first n-type contact electrode 229 and a first p-type contact electrode 227 are formed on a first initial substrate 210p on which ohmic electrodes 227' and 229' are formed. The first n-type contact electrode 229 is formed on the n-type semiconductor layer, and the first p-type contact electrode 227 is formed on the p-type semiconductor layer. The first n-type contact electrode 229 and the first p-type contact electrode 227 are formed of a reflective material.

[0439] 28 and 29D, a second insulating layer 273 is formed on a first initial substrate 210p having a first n-type contact electrode 229 and a first p-type contact electrode 227 formed thereon, and a first sub-scan line 2130R is formed on the second insulating layer 273. A contact hole is formed through the second insulating layer 273 at a position corresponding to the first n-type contact electrode 229, and the first sub-scan line 2130R is connected to the first n-type contact electrode 229 through the contact hole formed at the position corresponding to the first n-type contact electrode 229.

[0440] 28 and 29E, the first epitaxial stack 220 formed on the first initial substrate 210p is inverted and bonded to the substrate 210 with the first adhesive layer 250a interposed therebetween.

[0441] 28 and 29F, the first initial substrate 210p is removed after the first epitaxial stack 220 is bonded to the substrate 210. The first initial substrate 210p can be removed by various methods, such as a wet etching process, a dry etching process, a physical removal process, or a laser lift-off process. Although not shown, after the first initial substrate 210p is removed, an uneven portion PR is formed on the upper surface (n-type semiconductor layer) of the first epitaxial stack 220. The uneven portion PR is textured by various etching processes. For example, the uneven portion PR may be formed by various processes, such as a dry etching process using microphotography, a wet etching process using crystalline properties, a texturing process using a physical method such as sandblasting, an ion beam etching process, or a texturing process using the etching rate difference of a block copolymer.

[0442] 28 and 29G, a second epitaxial stack 230 is formed on a second initial substrate 210q. The second initial substrate 210q may be a sapphire substrate. The second epitaxial stack 230 is manufactured by forming an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on the second initial substrate 210q. A second p-type contact electrode 237 and a first wavelength pass filter 261 may be further formed on the second epitaxial stack 230.

[0443] Referring to Figures 28 and 29H, the second epitaxial stack 230 formed on the second initial substrate 210q is inverted and bonded to the first epitaxial stack 220 with the second adhesive layer 250b interposed therebetween.

[0444] 28 and 29I, after the second epitaxial stack 230 is bonded to the first epitaxial stack 220, the second initial substrate 210q is removed.

[0445] Although not shown, after the second initial substrate 210q is removed, an uneven portion PR is formed on the upper surface (n-type semiconductor layer) of the second epitaxial stack 230. The uneven portion PR may be formed by using a sapphire substrate that has been textured by various etching processes or patterned as the second initial substrate 210q. The second initial substrate 210q can be removed by various methods. For example, if the second initial substrate 210q is a sapphire substrate, the sapphire substrate can be removed by a laser lift-off process, a stress lift-off process, a chemical lift-off process, or a physical polishing process.

[0446] 28 and 29J, a third epitaxial stack 240 is formed on a third initial substrate 210r. The third initial substrate 210r may be a sapphire substrate. The third epitaxial stack 240 is manufactured by forming an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on the third initial substrate 210r. A third p-type contact electrode 247 and a second wavelength pass filter 263 may be further formed on the third epitaxial stack 240.

[0447] Referring to Figures 28 and 29K, the third epitaxial stack 240 formed on the third initial substrate 210r is flipped over and bonded to the second epitaxial stack 230 with the third adhesive layer 250c interposed therebetween.

[0448] 28 and 29L, the third initial substrate 210r is removed after the third epitaxial stack 240 is bonded to the second epitaxial stack 230, so that all of the first, second, and third epitaxial stacks 220, 230, and 240 are stacked on the substrate 210. Although not shown, after the third initial substrate 210r is removed, an uneven portion PR is formed on the upper surface (n-type semiconductor layer) of the third epitaxial stack 240. The uneven portion PR may be textured by various etching processes or may be formed by using a patterned sapphire substrate as the third initial substrate 210r.

[0449] Through the above-described steps, the first epitaxial stack 220 is connected to the first sub-scan line 2130R and the data line, i.e., the first p-type contact electrode 227, but the second and third epitaxial stacks 230 and 240 are not connected to the second and third sub-scan lines 2130G and 2130B and the data line 2120. Therefore, steps are performed to connect the second and third epitaxial stacks 230 and 240 to the second and third sub-scan lines 2130G and 2130B and the data line 2120.

[0450] Figures 30A to 35A are plan views sequentially showing the process for connecting the second and third epitaxial stacks 230 and 240 to the second and third sub-scan lines 2130G and 2130B and the data line 2120, and Figures 30B to 35B are cross-sectional views along lines I-I', IIa-IIa' and IIb-IIb' in Figures 30A to 35A, respectively.

[0451] 30A and 30B, a portion of the third epitaxial stack 240 is removed so as to expose a portion of the upper surface of the third p-type contact electrode 247. The third p-type contact electrode 247 functions as an etching stopper when the third epitaxial stack 240 is etched.

[0452] 31A and 31B, the third p-type contact electrode 247, the second wavelength pass filter 263, and a portion of the third adhesive layer 250c are etched, thereby exposing a portion of the upper surface of the second epitaxial stack 230. In this case, the contact area to which the third p-type contact electrode 247 and the data line 2120 are connected is not etched.

[0453] 32A and 32B, a portion of the second epitaxial stack 230 is removed to expose a portion of the upper surface of the second p-type contact electrode 237. The second p-type contact electrode 237 functions as an etch stop when the second epitaxial stack 230 is etched.

[0454] 33A and 33B, the second p-type contact electrode 237, the first wavelength pass filter 261, the second adhesive layer 250b, the first epitaxial stack 220, and a portion of the first insulating layer 271 are etched. As a result, the second insulating layer 273 and a portion of the first p-type contact electrode 227 are exposed to the outside. In this case, the contact area to which the second p-type contact electrode 237 and the data line 2120 are connected is not etched.

[0455] 34A and 34B, a third insulating layer 275 having first and second contact holes CH1 and CH2 formed therethrough is formed on the substrate 210. The portion to which the data line 2120 is connected, i.e., portions of the upper surfaces of the first, second, and third p-type contact electrodes 227, 237, and 247, is exposed through the first contact hole CH1. The portion to which the second and third sub-scan lines 2130G and 2130B are connected, i.e., portions of the upper surfaces of the n-type semiconductor layers of the second and third epitaxial stacks 230 and 240, is exposed through the first contact hole CH1. A portion of the upper surface of the conductor layer is exposed through the second contact hole CH2.

[0456] 35A and 35B, the second and third sub-scan lines 2130G and 2130B and the data line 2120 are formed on a substrate 210 on which first and second contact holes CH1 and CH2 are formed. The second and third sub-scan lines 2130G and 2130B and the data line 2120 are formed by forming a metal layer on the substrate 210 and patterning the metal layer. The second and third sub-scan lines 2130G and 2130B are connected to the second and third n-type semiconductor layers, respectively, through the second contact hole CH2, and the data line 2120 is connected to the first, second, and third p-type contact electrodes 227, 237, and 247 through the first contact hole CH1.

[0457] A fourth insulating layer 277 is formed on the substrate 210, on which the second and third sub-scan lines 2130G and 2130B and the data line 2120 are formed.

[0458] In the exemplary embodiment of the present disclosure, even if not shown, a light-opaque layer may be further disposed on the third insulating layer 275 or the fourth insulating layer 277 corresponding to the side of the pixel. The light-opaque layer may be formed by a DBR dielectric mirror, a metal reflective layer formed on the insulating layer, or an organic polymer. When a metal reflective layer is used as the light-opaque layer, the metal reflective layer may be in a floating state, in which the metal reflective layer is electrically isolated from other pixel components.

[0459] As described above, display devices according to exemplary embodiments of the present disclosure can be fabricated by stacking multiple epitaxial stacks in sequence and forming line portions and contact structures in the epitaxial stacks substantially simultaneously.

[0460] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure relate to light-emitting stack structures that can be used as light sources in a variety of devices.

[0461] 36A to 36C are cross-sectional views illustrating light-emitting stacked structures according to exemplary embodiments of the present disclosure.

[0462] 36A to 36C, a light emitting stack structure according to an exemplary embodiment of the present disclosure includes two epitaxial stacks stacked in sequence, namely, a first epitaxial stack 320 and a second epitaxial stack 330. The first and second epitaxial stacks 320 and 330 are disposed on a substrate 310.

[0463] The substrate 310 has a plate shape provided with a front surface and a rear surface.

[0464] The substrate 310 is formed of an optically transparent insulating material. The expression "the substrate 310 has optically transparent properties" refers to various cases, such as when the substrate 310 is transparent so that it transmits light substantially entirely, when the substrate 310 is semi-transparent so that it transmits only light having a specific wavelength, or when the substrate 310 is partially transparent so that it transmits only a portion of light having a specific wavelength.

[0465] The substrate 310 may be made of one of the growth substrates on which the epitaxial stack disposed on the front surface of the substrate 310, i.e., the first epitaxial stack 320, is grown. In this case, the substrate 310 may be a sapphire substrate, but the substrate 310 should not be limited thereto. That is, in addition to a sapphire substrate, various transparent insulating materials can be used as the substrate 310, as long as the material is transparent and has insulating properties and the epitaxial stack is disposed on the upper surface of the substrate 310. For example, the substrate 310 may be made of glass, quartz, an organic polymer, or an organic-inorganic composite material. In an exemplary embodiment of the present disclosure, a line section may be further disposed on the substrate 310 to apply a light-emitting signal and a common voltage to each epitaxial stack. For this purpose, the substrate 310 may be provided as a printed circuit board or a composite substrate obtained by forming the line section and / or the driving device on glass, quartz, silicon, an organic polymer, or an organic-inorganic composite material. The first epitaxial stack 320 includes an n-type semiconductor layer 321, an active layer 323, and a p-type semiconductor layer 325, which are stacked in this order. In this exemplary embodiment, the n-type semiconductor layer 321 and the p-type semiconductor layer 325 may have a single-layer structure, a multi-layer structure, or a superlattice layer. In addition, the active layer 323 may have a single quantum well structure or a multi-quantum well structure. The second epitaxial stack 330 includes an n-type semiconductor layer 331, an active layer 333, and a p-type semiconductor layer 335, which are stacked in this order. In this exemplary embodiment, the n-type semiconductor layer 331 and the p-type semiconductor layer 335 may have a single-layer structure, a multi-layer structure, or a superlattice layer. In addition, the active layer 333 may have a single quantum well structure or a multi-quantum well structure.

[0466] The n-type semiconductor layer 331, the active layer 333, and the p-type semiconductor layer 335 of the second epitaxial stack 330 may include a semiconductor material that emits red light.

[0467] As semiconductor materials that emit red light, aluminum gallium arsenide (AlGaAs), gallium arsenide phosphide (GaAsP), aluminum gallium indium phosphide (AlGaInP), and gallium phosphide (GaP) can be used. However, the semiconductor materials that emit red light should not be limited thereto, and various other materials can be used. In this exemplary embodiment, if the semiconductor layer emits light of another color, semiconductor materials corresponding to that other color may be selected.

[0468] First and second epitaxial stacks 320 and 330 are sequentially stacked on the front surface of substrate 310, and each of first and second epitaxial stacks 320 and 330 emits light. First epitaxial stack 320 emits color light having a relatively shorter wavelength and a relatively higher energy band than second epitaxial stack 330, and second epitaxial stack 330 emits color light having a relatively longer wavelength and a relatively lower energy band than first epitaxial stack 320.

[0469] In an exemplary embodiment of the present disclosure, the first and second epitaxial stacks 320 and 330 can emit light having different wavelength bands. That is, multiple epitaxial stacks are provided, and the epitaxial stacks have different energy bands. Each epitaxial stack can emit colored light in the visible light band among the light in various wavelength bands. For example, the first epitaxial stack 320 can emit a first colored light L1, and the second epitaxial stack 330 can emit a second colored light L2.

[0470] The first and second light L1 and L2 may be different color lights. The first and second color lights L1 and L2 may be color lights having different wavelength bands that are longer in order. In this exemplary embodiment, each of the first and second color lights L1 and L2 may exhibit a hue of a predetermined wavelength band, and may be selected so that the first and second color lights L1 and L2 exhibit white when mixed with each other. For example, the first color light L1 may be blue light, and the second color light L2 may be red light. As another example, the first color light L1 may be blue light, and the second color light L2 may be yellow light. As another example, the first color light L1 may be blue light, and the second color light L2 may be green light. When the first and second color lights L1 and L2 are mixed with each other, the mixed light of the first and second color lights L1 and L2 can exhibit approximately white color, but due to the difference in luminous intensity between the first and second color lights L1 and L2, there will be differences in color temperature and color coordinates.

[0471] For convenience of explanation, the first colored light L1 will be described as blue light, and the second colored light L2 will be described as red light.

[0472] Each epitaxial stack emits light toward the rear surface of the substrate 310. The rear surface direction corresponds to the opposite direction in which the first and second epitaxial stacks 320 and 330 are stacked. For ease of explanation, the direction in which the front surface of the substrate 310 faces will be referred to as the "front surface direction" or "upper direction," and the direction in which the rear surface of the substrate 310 faces will be referred to as the "rear surface direction" or "lower direction." However, the terms "upper" and "lower" indicate directions relative to each other and may vary depending on the arrangement or stacking direction of the light-emitting stacked structure.

[0473] Each of the first and second epitaxial stacks 320 and 330 emits light downward. That is, the first epitaxial stack 320 emits light toward the substrate 310 disposed below it, and the second epitaxial stack 330 emits light toward the first epitaxial stack 320 and the substrate 310 disposed below it. In this case, the first epitaxial stack 320 transmits most of the light emitted from the second epitaxial stack 330 disposed above it. For this reason, at least a portion, preferably the entire first epitaxial stack 320, is formed of an optically transparent material. The term "optically transparent material" refers not only to a material that transmits light substantially entirely, but also to a material that transmits light having a predetermined wavelength or a portion of light having a predetermined wavelength. In an exemplary embodiment, the first epitaxial stack 320 can transmit greater than about 60% of the light from the second epitaxial stack 330 disposed thereon. According to other embodiments, the first epitaxial stack 320 can transmit greater than about 80% of the light from the second epitaxial stack 330 disposed thereon, and according to other embodiments, the first epitaxial stack 320 can transmit greater than about 90% of the light from the second epitaxial stack 330 disposed thereon.

[0474] In the light emitting stack structure having the above-described structure according to the exemplary embodiment of the present disclosure, the first and second epitaxial stacks 320 and 330 can be driven independently because signal lines for applying light emitting signals to the first and second epitaxial stacks 320 and 330 are independently connected to the first and second epitaxial stacks 320 and 330. Therefore, colored light having various color temperatures and white light can be displayed depending on the light emitted from each epitaxial stack. In addition, because the first and second epitaxial stacks 320 and 330 emitting light having different wavelengths are formed to overlap each other, the light emitting stack structure can be formed within a small area.

[0475] As a result, the light-emitting stack structure according to the exemplary embodiments of the present disclosure can achieve white light close to sunlight, and can emit light with various hues according to the user's requirements.

[0476] Fig. 37A is a plan view showing a light-emitting stack structure according to an exemplary embodiment of the present disclosure, and Fig. 37B is a cross-sectional view taken along line II' in Fig. 37A. For ease of explanation, the structure of the light-emitting stack structure in a plan view will be described with reference to Fig. 37A, and the structure of the light-emitting stack structure in a cross section will be described with reference to Fig. 37B.

[0477] Referring to Figures 37A and 37B, the light emitting stack structure according to the exemplary embodiments of the present disclosure may have a substantially rectangular shape, but the shape of the light emitting stack structure should not be limited to a rectangular shape.

[0478] In an exemplary embodiment of the present disclosure, the light emitting stack structure includes, in a plan view, a light emitting area EA and a peripheral area PA. The first and second epitaxial stacks 320 and 330 are stacked within the light emitting area EA of the light emitting stack structure. The peripheral area PA is disposed adjacent to at least one side of the light emitting area EA. In this exemplary embodiment, the peripheral area PA is provided to surround the light emitting area EA. A contact portion is disposed within the peripheral area PA and electrically connects the first and second epitaxial stacks 320 and 330 to wiring. The contact portion is an area where a contact hole is provided through at least a portion of the first and second epitaxial stacks 320 and 330, and the contact portion includes first, second, and third contact portions 320C, 330C, and 340C. The first contact portion 320C is provided to supply a light-emitting signal to the first epitaxial stack 320, the second contact portion 330C is provided to supply a light-emitting signal to the second epitaxial stack 330, and the third contact portion 340C is provided to supply a common voltage to the first and second epitaxial stacks 320 and 330. In this illustrative embodiment, for electrical connection between the electrode portion and wiring, a first contact hole CH1 is provided in the first contact portion 320C, a second contact hole CH2 is provided in the second contact portion 330C, and third and fourth contact holes CH3 and CH4 are provided in the third contact portion 340C.

[0479] In this exemplary embodiment, the contact portions are disposed at positions corresponding to the corners of a rectangle. That is, if the light emitting stack structure has a rectangular shape, the first contact portion 320C, the second contact portion 330C, and the third contact portion 340C are disposed at three of the four corners of the rectangle so that the light emitting area is located in the center. However, the positions of the contact portions should not be limited thereto and can be changed in various ways. That is, the contact portions may be disposed at the center of the sides of the rectangle or inside the rectangle.

[0480] In this exemplary embodiment, the first and second epitaxial stacks 320 and 330 may overlap each other in a plan view. The first and second epitaxial stacks 320 and 330 may completely overlap each other in the light emitting area EA, but may not completely overlap each other in the peripheral area due to contact with the electrode portions.

[0481] Each of the first and second epitaxial stacks 320 and 330 includes an electrode portion for applying a light emission signal to the first and second epitaxial stacks 320 and 330 .

[0482] The electrode portion includes a first signal electrode 320E, a second signal electrode 330E, and a common electrode 340E.

[0483] The first signal electrode 320E, the second signal electrode 330E, and the common electrode 340E are spaced apart from one another in a plan view, and are disposed at positions corresponding to the first contact portion 320C, the second contact portion 330C, and the third contact portion 340C, respectively.

[0484] In this case, the first signal electrode 320E, the second signal electrode 330E, and the common electrode 340E may be disposed only in the peripheral area PA, or may be disposed across both the peripheral area PA and the light-emitting area EA. Because the light-emitting stack structure according to the exemplary embodiment of the present disclosure emits light L downward, the first signal electrode 320E, the second signal electrode 330E, and the common electrode 340E formed on the light-emitting stack structure are not disposed on the light path. Therefore, the first signal electrode 320E, the second signal electrode 330E, and the common electrode 340E are provided to cover the light-emitting area EA. In this exemplary embodiment, the first signal electrode 320E and the second signal electrode 330E are disposed in the peripheral area PA, and the common electrode 340E has an area larger than the first and second signal electrodes 320E and 330E and is disposed over a portion of the peripheral area PA and the light-emitting area EA.

[0485] The first signal electrode 320E and the common electrode 340E are connected to the first epitaxial stack 320. The second signal electrode 330E and the common electrode 340E are connected to the second epitaxial stack 330. The first signal electrode 320E is connected to the first epitaxial stack 320 through a first contact hole CH1, and the common electrode 340E is connected to the first epitaxial stack 320 through a third contact hole CH3. The second signal electrode 330E is connected to the second epitaxial stack 330 through a second contact hole CH2, and the common electrode 340E is connected to the second epitaxial stack 330 through a fourth contact hole CH4.

[0486] Next, the light-emitting stacked structure will be described in accordance with the stacking order with reference to FIGS. 37A and 37B.

[0487] According to this exemplary embodiment, a first epitaxial stack 320 is disposed on a substrate 310 .

[0488] A first p-type contact electrode 327 is disposed on the first epitaxial stack 320. Specifically, the first p-type contact electrode 327 is provided to contact the p-type semiconductor layer of the first epitaxial stack 320. The first p-type contact electrode 327 may include a transparent conductive material, such as a transparent conductive oxide (TCO), and may have a thickness of about 2000 angstroms to about 2 micrometers. Transparent conductive oxides may include tin oxide (SnO), indium oxide (InO), zinc oxide (ZnO), indium tin oxide (ITO), and indium tin zinc oxide (ITZO). The transparent conductive oxide may be deposited by chemical vapor deposition (CVD) or physical vapor deposition (PVD) using an evaporator or sputtering. The material of the first p-type contact electrode 327 should not be limited thereto.

[0489] In an exemplary embodiment of the present disclosure, the long-pass filter 360 is disposed on the first p-contact electrode 327. The long-pass filter 360 may be a component for providing colored light with high purity and high efficiency and can be selectively used in the light emitting stack. The long-pass filter 360 is used to block light having a relatively shorter wavelength from traveling to an epitaxial stack that emits light having a relatively longer wavelength.

[0490] In this illustrative embodiment, the long-wavelength pass filter 360 selectively transmits light having a predetermined wavelength. The long-wavelength pass filter 360 can transmit the second color light emitted from the second epitaxial stack 330 and can block or reflect light other than the second color light. Therefore, the second color light emitted from the second epitaxial stack 330 can travel downward, and the first color light emitted from the first epitaxial stack 320 does not need to travel toward the second epitaxial stack 330 but can be reflected or blocked by the long-wavelength pass filter 360.

[0491] The first color light is light having a relatively shorter wavelength and relatively higher energy than the second color light. When the first color light is incident on the second epitaxial stack 330, additional light emission may be stimulated in the second epitaxial stack 330. In this exemplary embodiment, the first color light can be prevented from entering the second epitaxial stack 330 by the long-pass filter 360.

[0492] The long pass filter 360 is disposed in the light emitting area EA and the peripheral area PA, although the long pass filter 360 may not be disposed in the peripheral area (AP) if desired.

[0493] A second epitaxial stack 330 is disposed on the first epitaxial stack 320 with a first p-type contact electrode 327 disposed thereon with an adhesion layer 350 interposed therebetween.

[0494] The adhesive layer 350 can include a non-conductive material or an optically transparent material. For example, the adhesive layer 350 can include an optically clear adhesive (OCA). The material of the adhesive layer 350 should not be particularly limited as long as the material of the adhesive layer 350 is optically transparent and can stably bond each epitaxial stack. For example, the adhesive layer 350 can include organic materials such as SU-8, various resists, parylene, epoxy-based polymers such as poly(methyl methacrylate) (PMMA) and benzocyclobutene (BCB), and inorganic materials such as silicon oxide, aluminum oxide, and fused glass. Also, if necessary, a conductive oxide can be used as the adhesive layer. In this case, the conductive oxide needs to be insulated from other components. When an organic material is used as the adhesive layer and fused glass is used as the inorganic material, the first and second epitaxial stacks 320 and 330 are bonded together by coating the material on the adhesive sides of the first and second epitaxial stacks 320 and 330 and applying high temperature and pressure to the material under high vacuum conditions. When an inorganic material (other than fused glass) is used as the adhesive layer, the first and second epitaxial stacks 320 and 330 are bonded together by depositing the inorganic material on the adhesive sides of the first and second epitaxial stacks 320 and 330, planarizing the inorganic material using chemical mechanical planarization (CMP), performing a plasma treatment on the surface of the inorganic material, and bonding the first and second epitaxial stacks 320 and 330 together under high vacuum conditions.

[0495] A second epitaxial stack 330 is disposed on the adhesion layer 350 .

[0496] By removing portions of the n-type semiconductor layer, the active layer, and the p-type semiconductor layer, a mesa M is formed in the second epitaxial stack 330. Portions of the semiconductor layers (specifically, portions of the n-type semiconductor layer and the active layer) are removed from portions where the mesa M is not formed, thereby exposing the top surface of the n-type semiconductor layer. The area where the mesa M is arranged may overlap with the light emitting area EA, and the area where the mesa M is not arranged may overlap with the peripheral area PA, in particular, the contact portion.

[0497] A second n-type contact electrode 339 is disposed on the exposed upper surface of the n-type semiconductor layer. A second p-type contact electrode 337 is disposed on top of the p-type semiconductor layer on which the mesa is formed, with an ohmic electrode 337' and a first insulating layer 371 interposed therebetween.

[0498] The first insulating layer 371 covers the upper surface of the second epitaxial stack 330 and includes a contact hole formed therethrough corresponding to the portion where the ohmic electrode 337' will be disposed. The ohmic electrode 337' is disposed corresponding to the area where the third contact portion 340C will be disposed and may have various shapes, for example, a donut shape as shown in FIG. 37A.

[0499] The ohmic electrode 337' can be used for ohmic contact and can include a variety of materials. In an exemplary embodiment of the present disclosure, the ohmic electrode 337' can include Au(Zn) or Au(Be). In this case, the material for the ohmic electrode 337' has a lower reflectivity than Ag, Al, and Au, so an additional reflective electrode can be disposed. Ag or Au can be used as the material for the additional reflective electrode, and a layer containing Ti, Ni, Cr, or Ta can be disposed as an adhesion layer for adhesion to adjacent components. In this case, the adhesion layer is thinly deposited on the upper and lower surfaces of the reflective electrode containing Ag or Au.

[0500] The second p-type contact electrode 337 is disposed on the first insulating layer 371. The second p-type contact electrode 337 may overlap the light emitting area EA and is provided to cover the entire light emitting area EA in a plan view. The second p-type contact electrode 337 includes a reflective material and can reflect light from the second epitaxial stack 330 downward. Various reflective metals, such as Ag, Al, and Au, can be used as the reflective material for the second p-type contact electrode 337, and a layer including Ti, Ni, Cr, or Ta may be disposed as an adhesion layer for adhesion to adjacent components.

[0501] In particular, if the second epitaxial stack 330 emits red light, the second p-type contact electrode 337 may include a material having high reflectivity in the wavelength band of red light. For example, the second p-type contact electrode 337 may include "Au," which has high reflectivity in the wavelength band of red light. In this case, "Au" can absorb blue light leaking from the bottom of the second p-type contact electrode 337, thereby reducing unnecessary color interference.

[0502] In this exemplary embodiment, the first insulating layer 271 is formed to have reflective properties to facilitate reflection of light from the second epitaxial stack 330. For example, the first insulating layer 371 may have an omni-directional reflector (ODR) structure.

[0503] A second insulating layer 373 is disposed on top of the first insulating layer 371, on which the second p-type contact electrode 337 is disposed. The second insulating layer 373 covers the top surface of the second epitaxial stack 330 and the side surfaces of each component disposed below the second insulating layer 373.

[0504] In this exemplary embodiment, the second insulating layer 373 may further have reflectivity. In addition, although not shown in detail, in the exemplary embodiment of the present disclosure, an optically opaque layer may be further disposed on a side portion of the second insulating layer 373 corresponding to the side surface of the light-emitting stack. The optically opaque layer may act as a light-blocking layer to prevent light from the first and second epitaxial stacks 320 and 330 from emitting through the side surface of the light-emitting stack, and may include a material that absorbs or reflects light.

[0505] The optically opaque layer should not be particularly limited as long as it absorbs or reflects light to block light transmission. In exemplary embodiments of the present disclosure, the optically opaque layer may be a distributed Bragg reflector (DBR) dielectric mirror, a metal reflective layer formed on an insulating layer, or a black organic polymer layer. When a metal reflective layer is used as the optically opaque layer, the metal reflective layer may be in a floating state, in which the metal reflective layer is electrically isolated from other components of the light-emitting stack structure.

[0506] A light-impermeable layer disposed on the side of a light-emitting stack structure can prevent light emitted from a particular light-emitting stack structure from affecting adjacent light-emitting stack structures or from mixing with light emitted from adjacent light-emitting stack structures.

[0507] The first and second signal electrodes 320E and 330E and the common electrode 340E are disposed on the second insulating layer 373. The first and second signal electrodes 320E and 330E and the common electrode 340E may have a single layer or multiple layers of metal. For example, the first and second signal electrodes 320E and 330E and the common electrode 340E may include a variety of materials, including Al, Ti, Cr, Ni, Au, Ag, Sn, W, and Cu metals or alloys thereof.

[0508] The first and second signal electrodes 320E and 330E and the common electrode 340E are connected to the corresponding components via first, second, third and fourth contact holes CH1, CH2, CH3 and CH4 provided underneath.

[0509] The first signal electrode 320E is connected to the n-type semiconductor layer of the first epitaxial stack 320 through a first contact hole CH1. The first contact hole CH1 is provided by penetrating, from top to bottom, the second insulating layer 373, the first insulating layer 371, the second epitaxial stack 330, the adhesive layer 350, the long wavelength pass filter 360, the first p-type contact electrode 327, and a portion of the first epitaxial stack 320. In particular, portions of the p-type semiconductor layer and the active layer of the first epitaxial stack 320 are removed to expose the upper surface of the n-type semiconductor layer of the first epitaxial stack 320, and therefore the first signal electrode 320E is connected to the n-type semiconductor layer of the first epitaxial stack 320 through the first contact hole CH1.

[0510] The second signal electrode 330E is connected to the n-type semiconductor layer of the second epitaxial stack 330 through a second contact hole CH2. The second contact hole CH2 is provided by penetrating the second insulating layer 373 and the first insulating layer 371 from above. Therefore, the upper surface of the n-type semiconductor layer of the second epitaxial stack 330 is exposed through the second contact hole CH2, and therefore the second signal electrode 330E is connected to the n-type semiconductor layer of the second epitaxial stack 330 through the second contact hole CH2.

[0511] The common electrode 340E is connected to the first p-type contact electrode 327 of the first epitaxial stack 320 via a third contact hole CH3. The third contact hole CH3 is provided by penetrating, from above, the second insulating layer 373, the first insulating layer 371, the second epitaxial stack 330, the adhesive layer 350, and the long wavelength pass filter 360. Therefore, the upper surface of the first p-type contact electrode 327 is exposed, and the common electrode 340E is connected to the first p-type contact electrode 327 via the third contact hole CH3.

[0512] In addition, the common electrode 340E is connected to the second p-type contact electrode 337 of the second epitaxial stack 330 through a fourth contact hole CH4. The fourth contact hole CH4 is provided by penetrating a portion of the second insulating layer 373. Therefore, the upper surface of the second p-type contact electrode 337 is exposed, and the common electrode 340E is connected to the second p-type contact electrode 337 through the fourth contact hole CH4.

[0513] The light emitting stack structure having the above-described structure emits light downward using light emitted from the first and second epitaxial stacks 320 and 330. In this case, separate driving signals are applied to the first and second epitaxial stacks 320 and 330 via the first and second signal electrodes 320E and 330E, respectively, so that the light emissions of the first and second epitaxial stacks 320 and 330 can be independently controlled. That is, whether the first epitaxial stack 320 emits light can be determined by the light emitting signal and common voltage applied to the first epitaxial stack 320 via the first signal electrode 320E and the common electrode 340E, respectively. Whether the second epitaxial stack 330 emits light can be determined by the light emitting signal and common voltage applied to the second epitaxial stack 330 via the second signal electrode 330E and the common electrode 340E, respectively. As a result, the light emissions of the first epitaxial stack 320 and the second epitaxial stack 330 may differ individually depending on the signal applied to the first signal electrode 320E and the signal applied to the second signal electrode 330E.

[0514] In the above-described embodiment, a common voltage is applied to the p-type semiconductor layer of the first and second epitaxial stacks 320 and 330, and an emission signal is applied to the n-type semiconductor layer of the first and second epitaxial stacks 320 and 330, but the embodiments of the present disclosure should not be limited thereto. According to another embodiment of the present disclosure, a common voltage is applied to the n-type semiconductor layer of the first and second epitaxial stacks 320 and 330, and an emission signal is applied to the p-type semiconductor layer of the first and second epitaxial stacks 320 and 330. Such a structure can be easily realized by arranging the components of each epitaxial stack in the order of p-type semiconductor layer, active layer, and n-type semiconductor layer, which is different from the stacking order of the semiconductor layers in the present disclosure, i.e., n-type semiconductor layer, active layer, and p-type semiconductor layer.

[0515] Therefore, the light emitting stack structure according to this exemplary embodiment can provide white light with different color temperatures depending on the operation mode by separately driving the first and second epitaxial stacks. In particular, the color temperature can be finely controlled by separately controlling the currents applied to the first and second epitaxial stacks. Therefore, when the light emitting stack structure according to this exemplary embodiment is applied to a lighting device, the light can be controlled according to the user's sensitivity. In addition, white light is generated by mixing colored light from the first and second epitaxial stacks in various ways, resulting in white light with a high color rendering index and a wide correlated color temperature.

[0516] Furthermore, when displaying colors, the light-emitting stack structure having the above-described structure provides different color lights through overlapping areas rather than through different areas on a plane, thereby enabling miniaturization and integration of light-emitting elements. According to the prior art, light-emitting elements emitting different color lights, e.g., red and blue light, are spaced apart on a plane to achieve white light. Therefore, since the light-emitting elements are spaced apart on a plane, the area occupied by the light-emitting elements in the prior art is relatively large. In contrast, according to the present disclosure, light-emitting elements emitting different color lights are arranged in the same overlapping area to form a light-emitting stack structure, thereby achieving white light in a significantly smaller area than the prior art. Therefore, high-resolution display devices can be manufactured in a small area.

[0517] Furthermore, even in the case of conventional light emitting devices manufactured using a stacking method, the conventional light emitting devices are manufactured by individually forming contact portions within each light emitting device, for example, by individually and separately forming the light emitting devices and connecting the light emitting devices to each other using wiring. As a result, the structure of the light emitting device is complex and the light emitting device is not easy to manufacture. However, the light emitting stack structure according to the exemplary embodiment of the present disclosure is manufactured by sequentially stacking multiple epitaxial stacks on a single substrate and connecting line portions to the epitaxial stacks with a minimal number of steps, thereby simplifying the structure and manufacturing method of the light emitting stack structure.

[0518] The light emitting stack structure having the above-described structure can be manufactured by sequentially stacking first and second epitaxial stacks on a substrate, as will be described with reference to the accompanying drawings. The light emitting stack structure according to the exemplary embodiment of the present disclosure may be manufactured in a single unit, or multiple light emitting stack structures may be formed substantially simultaneously using a substrate having a large area. When the light emitting stack structures are formed substantially simultaneously, recessed portions may be formed to electrically and physically separate adjacent light emitting stack structures from each other, and each light emitting stack structure can be separated into a single light emitting stack structure by cutting the portion corresponding to the recessed portion in a final process.

[0519] In the following examples, one light emitting stack structure is shown as a representative example. When multiple light emitting stack structures are formed, the parts corresponding to the outermost lines in the drawings correspond to the periphery of the substrate and the boundaries between adjacent light emitting stack structures.

[0520] Figures 38A, 39A, 40A, 41A, 42A and 43A are plan views sequentially showing a method for manufacturing a light-emitting stacked structure according to an exemplary embodiment of the present disclosure, and Figures 38B, 39B, 40B to 40G, 41B to 41D, 42B and 43B are cross-sectional views taken along line II in Figures 38A, 39A, 40A, 41A, 42A and 43A, respectively.

[0521] A light emitting stack structure according to an exemplary embodiment of the present disclosure may be manufactured by forming a first epitaxial stack 320 on a substrate 310, forming a second epitaxial stack 330 on a separate temporary substrate, forming the second epitaxial stack 330 on the first epitaxial stack 320, and forming an electrode portion connecting the first and second epitaxial stacks 320 and 330. For convenience of explanation, the manufacture of the light emitting stack structure will be described below in the order of forming the second epitaxial stack 330 on the temporary substrate and then forming the second epitaxial stack 330 on the first epitaxial stack 230.

[0522] Referring to Figures 38A and 38B, a first epitaxial stack 320 is disposed on a first temporary substrate 310p.

[0523] The first temporary substrate 310p may be a semiconductor substrate 310 for forming the second epitaxial stack 330. The first temporary substrate 310p can be configured differently depending on the semiconductor layer to be formed. If the second epitaxial stack 330 includes a semiconductor layer that emits red light, the first temporary substrate 310p may be a gallium arsenide (GaAs) substrate. The second epitaxial stack 330 is fabricated by forming an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on the first temporary substrate 310p, and then removing portions of the active layer and the p-type semiconductor layer, and, if necessary, a portion of the n-type semiconductor layer, to form a mesa structure M. Since the mesa structure M is formed, the upper surface of the n-type semiconductor layer of the second epitaxial stack 330 is exposed.

[0524] 39A and 39B, a second n-type contact electrode 339, an ohmic electrode 337′, and a first insulating layer 371 are formed on the second epitaxial stack 330 on which the mesa structure M is formed. The second n-type contact electrode 339 is disposed in an area corresponding to the second contact portion 330C, and the ohmic electrode 337′ is disposed in an area corresponding to the third contact portion 340C. A contact hole exposed through the upper surface of the p-type semiconductor layer of the second epitaxial stack 330 is formed through the first insulating layer 371 in the area where the ohmic electrode 337′ is to be formed, and the ohmic electrode 337′ is formed in the contact hole.

[0525] 40A and 40B, the second p-type contact electrode 337 is formed on the first temporary substrate 310p on which the first insulating layer 371 is formed. The second p-type contact electrode 337 may include a reflective material and is formed to cover the light emitting area EA. The second p-type contact electrode 337 is formed by forming a reflective conductive material on the entire surface of the first insulating layer 371 and the ohmic electrode 337′ and patterning the reflective conductive material using a photolithography process.

[0526] Referring to Figures 40A and 40C, the second epitaxial stack 330, on which the second p-type contact electrode 337 is formed, is inverted together with the first temporary substrate 310p and bonded to a second temporary substrate 310q with a temporary adhesive layer 351 interposed therebetween.

[0527] The temporary adhesive layer 351 is removed after a predetermined process is performed by bonding the second epitaxial stack 330 to the second temporary substrate 310q. Therefore, the temporary adhesive layer 351 is formed of a material selected from among materials that have a predetermined adhesive strength and are easy to remove. The material of the temporary adhesive layer 351 should not be particularly limited.

[0528] The second temporary substrate 310q is a carrier substrate on which the second epitaxial stack 330 is temporarily bonded, and the type of the second temporary substrate 310q should not be particularly limited.

[0529] 40A and 40D, the first temporary substrate 310p is removed after the second epitaxial stack 330 is bonded to the second temporary substrate 310q. The first temporary substrate 310p can be removed by various methods, such as a wet etching process, a dry etching process, a physical removal process, or a laser lift-off process. However, the method for removing the first temporary substrate 310p should not be limited thereto. The first temporary substrate 310p can be removed by forming a sacrificial layer between the first temporary substrate 310p and the second epitaxial stack 330 and removing the sacrificial layer.

[0530] 40A and 40E, the first epitaxial stack 320 is fabricated separately from the second epitaxial stack 330. The first epitaxial stack 320 can be fabricated by sequentially forming an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on the substrate 310. A first p-type contact electrode 327, a long wavelength pass filter 360, and an adhesion layer 350 are sequentially formed on the first epitaxial stack 320.

[0531] 40A and 40F, the second epitaxial stack 330 formed on the second temporary substrate 310q is inverted and bonded to the first epitaxial stack 320 with an adhesive layer 350 interposed therebetween. In this case, the lower surface of the n-type semiconductor layer of the second epitaxial stack 330 is positioned facing the p-type semiconductor layer of the first epitaxial stack 320, and then the second epitaxial stack 330 is bonded to the first epitaxial stack 320. The adhesive layer 350 may include a non-conductive material and a material having optically transparent properties. For example, an optically transparent adhesive may be used as the adhesive layer 350.

[0532] 40A and 40G, the temporary adhesive layer 351 and the second temporary substrate 310q disposed on the second epitaxial stack 330 are removed after the second epitaxial stack 330 is bonded onto the first epitaxial stack 320. The second temporary substrate 310q can be removed by various methods. For example, if the second temporary substrate 310q is a sapphire substrate, the sapphire substrate can be removed by a laser lift-off process, a stress lift-off process, a chemical lift-off process, or a physical polishing process.

[0533] As described above, after the first epitaxial stack 320 and the second epitaxial stack 330 are formed on the substrate 310, the electrodes and contacts are formed, as will be described in detail below.

[0534] 41A and 41B, portions of the first insulating layer 371, the second epitaxial stack 330, the adhesive layer 350, and the long-wavelength pass filter 360 are removed from areas corresponding to the first contact portion 320C and the third contact portion 340C to form the first temporary contact hole CH1′ and the third contact hole CH3, respectively. In this case, recessed portions are formed along the periphery of the light-emitting stack having the first temporary contact hole CH1′ and the third contact hole CH3. The recessed portions are formed to electrically and physically isolate adjacent light-emitting stacks from each other when the light-emitting stacks are formed.

[0535] The first temporary contact hole CH1′, the third contact hole CH3, and the recessed portion R are formed using a photolithography process. The upper surface of the first p-type contact electrode 327 is exposed to the outside through the first temporary contact hole CH1′, the third contact hole CH3, and the recessed portion R.

[0536] 41A and 41C, the first p-type contact electrode 327 and portions of the first epitaxial stack 320, specifically, portions of the p-type semiconductor layer and active layer of the first epitaxial stack 320, are removed from an area corresponding to the first contact portion 320C to form a first contact hole CH1. In this case, the portions of the p-type semiconductor layer and active layer of the first epitaxial stack 320 are removed along the periphery of the light-emitting stacked structure, so that the recess portion is further etched.

[0537] Additional etching of the first contact hole CH1 and the recessed portion may be performed by a photolithography process, so that the top surface of the n-type semiconductor layer of the first epitaxial stack 320 is exposed to the outside through the first contact hole CH1 in the area corresponding to the first contact portion 320C and through the recessed portion within the periphery of the light emitting stack.

[0538] 41A and 41D, portions of the n-type semiconductor layer of the first epitaxial stack 320 are removed along the periphery of the light emitting stack, thereby further etching recessed portions to electrically and physically isolate each light emitting stack from its adjacent light emitting stack. In this operation, the additional etching of the recessed portions may be performed by a photolithography process, and the upper surface of the substrate 310 is exposed around the periphery of the light emitting stack.

[0539] 42A and 42B, a second insulating layer 373 is formed and patterned over the entire surface of the substrate 310 to form second contact holes CH2 and fourth contact holes CH4 in the second contact portion 330C and the third contact portion 340C, respectively. The second insulating layer 373 covers not only the upper components of the second epitaxial stack 330, but also the first and second epitaxial stacks 320 and 330 and the side surfaces of the light emitting stack where the recessed portions are formed.

[0540] The second contact hole CH2 and the fourth contact hole CH4 are formed by a photolithography process.

[0541] When the second contact hole CH2 is formed, the first insulating film 371 disposed under the second insulating layer 373 is patterned, thereby exposing the upper surface of the second n-type contact electrode 339 to the outside. The fourth contact hole CH4 is formed so that a portion of the upper surface of the second p-type contact electrode 337 is exposed to the outside at the third contact portion 340C. In this illustrative embodiment, the area where the fourth contact hole CH4 is formed overlaps with the area where the ohmic electrode 337′ is formed, but this is merely for convenience of explanation and should not be construed as limiting the present invention.

[0542] In this illustrative embodiment, when the second insulating layer 373 is formed in the first and third contact holes CH1 and CH3 and patterned, the second insulating layer 373 on the top surface of the n-type semiconductor layer of the first epitaxial stack 320 and the second insulating layer 373 on the top surface of the first p-type contact electrode 327 are removed so as to maintain the exposure of the top surface of the n-type semiconductor layer of the first epitaxial stack 320 and the top surface of the first p-type contact electrode 327. However, the second insulating layer 373 formed on the sidewalls of the first and third contact holes CH1 and CH3 can be maintained without being removed.

[0543] Referring to Figures 43A and 43B, a first signal electrode 320E, a second signal electrode 330E and a common electrode 340E are formed on a substrate 310 in which first, second, third and fourth contact holes CH1, CH2, CH3 and CH4 are formed.

[0544] The first signal electrode 320E, the second signal electrode 330E, and the common electrode 340E are formed by a photolithography process, and the first signal electrode 320E, the second signal electrode 330E, and the common electrode 340E are formed by a single process using one mask.

[0545] The first signal electrode 320E is formed in an area corresponding to the first contact portion 320C, the second signal electrode 330E is formed in an area corresponding to the second contact portion 330C, and the common electrode 340E is formed in an area corresponding to the third contact portion 340C. Therefore, the first signal electrode 320E is connected to the n-type semiconductor layer of the first epitaxial stack 320 through the first contact hole CH1, the second signal electrode 330E is directly connected to the second n-type contact electrode 339 through the second contact hole CH2, and the common electrode 340E is connected to the first p-type contact electrode 327 and the second p-type contact electrode 337 through the third and fourth contact holes CH3 and CH4, respectively.

[0546] Each light emitting stack structure is manufactured by the above-described operations. Although not shown, when multiple light emitting stack structures are manufactured substantially simultaneously, a process of cutting the substrate 310 along the boundaries of the light emitting stack structures may be further performed. When multiple light emitting stack structures are manufactured substantially simultaneously using a substrate having a large area and the light emitting stack structures are cut to divide the light emitting stack structures, the manufacturing efficiency of the light emitting stack structures can be improved and the manufacturing cost of the light emitting stack structures can be reduced.

[0547] The light emitting stack structure according to the exemplary embodiment of the present disclosure may further include various components to provide highly efficient uniform light. For example, the light emitting stack structure according to the exemplary embodiment of the present disclosure may include various uneven portions PR on the light emitting surface.

[0548] 44 is a cross-sectional view showing a light-emitting stack structure according to an exemplary embodiment of the present disclosure. Specifically, FIG. 44 shows a concave-convex portion PR formed on a second epitaxial stack 330. In the following embodiment, to avoid redundancy, features different from those of the above-described embodiment will be mainly described. Parts not described are assumed to be the same as or similar to those of the above-described embodiment.

[0549] The light emitting stack structure according to the exemplary embodiment of the present disclosure may include a roughened portion PR formed on the second epitaxial stack 330. In the exemplary embodiment of the present disclosure, the roughened portion PR is disposed on a lower surface of the n-type semiconductor layer corresponding to the light emitting surface of the second epitaxial stack 330.

[0550] The uneven portion PR is used to improve luminous efficiency. The uneven portion PR can be provided in various shapes, such as a polygonal pyramid, a hemisphere, or a rough surface, on which uneven portions are randomly arranged. The uneven portion PR can be formed by texturing using various etching processes. For example, the uneven portion PR can be formed by various processes, such as a dry etching process using microphotography, a wet etching process using crystalline properties, a texturing process using a physical method such as sandblasting, an ion beam etching process, or a texturing process using the etching rate difference of a block copolymer.

[0551] In an exemplary embodiment of the present disclosure, there may be a difference in luminous intensity between the first and second color lights from the first and second epitaxial stacks, which may induce a difference in color temperature when white light is generated. In this exemplary embodiment, textured portions are selectively formed on the light-emitting surfaces of the first and second epitaxial stacks to improve light-emitting efficiency, thereby reducing the difference in luminous intensity between the first and second color lights. In particular, color light corresponding to red is less visible than blue, and the difference in luminous intensity of the light can be reduced by texturing the second epitaxial stack.

[0552] The step of forming an uneven portion on the lower surface of the n-type semiconductor layer of the second epitaxial stack is performed after the operation shown in Figure 40D, and Figure 45 is a cross-sectional view showing the uneven portion formed on the second epitaxial stack of Figure 40D.

[0553] Referring to FIG. 45, after the first temporary substrate 310p in contact with the n-type semiconductor layer of the second epitaxial stack 330 is removed, a texturing process is performed on the exposed n-type semiconductor layer to form a textured portion PR.

[0554] According to an exemplary embodiment of the present disclosure, the uneven portion is provided with another epitaxial stack and the substrate can be removed.

[0555] 46 is a cross-sectional view of a light emitting stack structure according to an exemplary embodiment of the present disclosure. Specifically, FIG. 46 illustrates a structure in which the substrate 310 is removed and a textured portion PR is formed on the first epitaxial stack 320 in addition to the second epitaxial stack 330.

[0556] 46, the light emitting stack structure according to the exemplary embodiment of the present disclosure may have a structure in which the substrate 310 is removed. Because the substrate 310 has a relatively large thickness, the thickness of the light emitting stack structure can be significantly reduced by removing the substrate 310. Therefore, when a predetermined device is manufactured by transferring the light emitting stack structure from which the substrate 310 has been removed onto a separate wiring substrate, it is easy to thin the predetermined device.

[0557] According to this illustrative embodiment, the uneven portion PR can be disposed on the first epitaxial stack 320 to improve light efficiency. That is, the uneven portion PR is disposed on the lower surface of the n-type semiconductor layer corresponding to the light emitting surface of the first epitaxial stack 320. In this case, a patterned sapphire substrate is used as the substrate 310, and once the patterned sapphire substrate is removed, the uneven portion PR can be easily formed on the light emitting surface of the first epitaxial stack 320.

[0558] According to exemplary embodiments of the present disclosure, the light emitting stack structure may further include additional components for a high color rendering index and a wide correlated color temperature. For example, the light emitting stack structure may further include a light conversion layer for converting at least a portion of the light emitted from the first and second epitaxial stacks, respectively, into light having another wavelength.

[0559] 47 and 48 are cross-sectional views of light emitting stack structures having a light conversion layer according to exemplary embodiments of the present disclosure, with Fig. 47 showing the light emitting stack structure with the substrate removed and Fig. 48 showing the light emitting stack structure including the substrate.

[0560] 47, a light conversion layer 380 may be additionally disposed on a lower surface corresponding to the light emitting surface of the first epitaxial stack 320. Referring to FIG. 48, a light conversion layer 380 may be additionally disposed on a lower surface of the substrate 310, and the light conversion layer 380 may be provided to selectively cover the side surfaces of the light emitting stack structure.

[0561] The light conversion layer 380 may include a fluorescent material, nanostructures such as quantum dots, an organic material capable of color conversion, or a combination thereof. For example, when a fluorescent material is used as the material of the light conversion layer 380, the fluorescent material can absorb light having a predetermined wavelength and emit light having a wavelength longer than the predetermined wavelength. The fluorescent material is provided in a form mixed with a transparent or translucent binder such as PDMS (polydimethylsiloxane), PI (polyimide), PMMA (poly(methyl 2-methylpropenoate)), or ceramic.

[0562] In this exemplary embodiment, since the light emitting stack includes the light conversion layer 380, the light emitting stack can output light having a wavelength different from the first color light and / or the second color light emitted from the first and second epitaxial stacks 320 and 330. Therefore, in the exemplary embodiment of the present disclosure, the final provided light can be mixed to obtain a high color rendering index and a wide correlated color temperature.

[0563] The light emitting stack structure according to the exemplary embodiments of the present disclosure may be used independently, but should not be limited thereto, i.e., the light emitting stack structure may be used as various types of light sources after being mounted on a base substrate on which wiring is formed, such as a printed circuit board.

[0564] 49 and 50 are plan views illustrating a light emitting stack mounted on a printed circuit board 3110 according to an exemplary embodiment of the present disclosure.

[0565] 49, a plurality of light emitting stack structures 3120 according to an exemplary embodiment of the present disclosure are arranged along the vertical direction on a printed circuit board 3110 extending in one direction. Referring to FIG. 50, a plurality of light emitting stack structures 3120 according to an exemplary embodiment of the present disclosure are arranged in a matrix on a printed circuit board 3110 having a predetermined shape, such as a rectangular shape, and a predetermined area. The shape of the printed circuit board 3110 and the arrangement of the light emitting stack structures 3120 should not be limited thereto and can be varied in various ways. Therefore, the light emitting stack structure can provide light in the form of a point light source, a linear light source, or a surface light source.

[0566] Terminals are formed on the printed circuit board 3110, which can respectively apply a light-emitting signal and a common voltage to the light-emitting stack structure, and the light emission of the light-emitting stack structure may be determined by the light-emitting signal and the common voltage applied to the light-emitting stack structure via the terminals.

[0567] The light-emitting stack structure according to the exemplary embodiments of the present disclosure can be used in various lighting devices requiring white light, such as backlight units included in passive display devices and / or as indoor and / or outdoor lighting in daily life.

[0568] FIG. 51 is a schematic cross-sectional view of a light emitting diode stack 400 for a display according to one exemplary embodiment of the present disclosure.

[0569] Referring to FIG. 51, the light-emitting diode stack 400 includes a support substrate 451, a first LED stack 423, a second LED stack 433, a third LED stack 443, a reflective electrode 425, an ohmic electrode 426, a first insulating layer 427, a second insulating layer 428, an interconnection line 429, a second-p transparent electrode 435, a third-p transparent electrode 445, a first color filter 437, a second color filter 447, a first bonding layer 453, a second bonding layer 455, and a third bonding layer 457.

[0570] The support substrate 451 supports the semiconductor stacks 423, 433, and 443. The support substrate 451 may include, but is not limited to, circuitry on or within its surface. The support substrate 451 may include, for example, a glass, a sapphire substrate, a Si substrate, or a Ge substrate.

[0571] Each of the first LED stack 423, the second LED stack 433, and the third LED stack 443 includes an n-type semiconductor layer 423 a, 433 a, or 443 a, a p-type semiconductor layer 423 b, 433 b, or 443 b, and an active layer interposed therebetween. The active layer may have a multiple quantum well structure.

[0572] For example, the first LED stack 423 may be an inorganic light emitting diode adapted to emit red light, the second LED stack 433 may be an inorganic light emitting diode adapted to emit green light, and the third LED stack 443 may be an inorganic light emitting diode adapted to emit blue light. The first LED stack 423 may include a GaInP-based well layer, and each of the second LED stack 433 and the third LED stack 443 may include a GaInN-based well layer.

[0573] At the same time, both surfaces of each of the first to third LED stacks 423, 433, and 443 are n-type and p-type semiconductor layers, respectively. In this illustrative embodiment, the first conductivity type semiconductor layers 423a, 433a, and 443a of the first to third LED stacks 423, 433, and 443 are n-type semiconductor layers, and the second conductivity type semiconductor layers 423b, 433b, and 443b of the first to third LED stacks 423, 433, and 443 are p-type semiconductor layers. Because the third LED stack 443 has an n-type upper surface, a roughened surface is formed on the upper surface of the third LED stack 443 by chemical etching. However, it should be understood that the present disclosure is not limited in this respect, and the semiconductor types of the upper and lower surfaces of each LED stack can vary.

[0574] The first LED stack 423 is disposed near the support substrate 451, the second LED stack 433 is disposed on the first LED stack 423, and the third LED stack 443 is disposed on the second LED stack 433. Since the first LED stack 423 emits light having a longer wavelength than the second and third LED stacks 433 and 443, light generated from the first LED stack 423 is emitted to the outside via the second and third LED stacks 433 and 443. Furthermore, since the second LED stack 433 emits light having a longer wavelength than the third LED stack 443, light generated from the second LED stack 433 is emitted to the outside via the third LED stack 443.

[0575] The reflective electrode 425 forms ohmic contact with the second conductive type semiconductor layer of the first LED stack 423 and reflects light generated from the first LED stack 423. For example, the reflective electrode 425 may include an ohmic contact layer 425a and a reflective layer 425b.

[0576] The ohmic contact layer 425a is in partial contact with the second conductive type semiconductor layer, i.e., the p-type semiconductor layer. To prevent light absorption by the ohmic contact layer 425a, the area where the ohmic contact layer 425a contacts the p-type semiconductor layer does not exceed 50% of the entire area of ​​the p-type semiconductor layer. The reflective layer 425b covers the ohmic contact layer 425a and the insulating layer 427. As shown in the figure, the reflective layer 425b can cover the entire ohmic contact layer 425a, but is not limited to this. Alternatively, the reflective layer 425b may cover only a portion of the ohmic contact layer 425a.

[0577] Because the reflective layer 425b covers the first insulating layer 427, an omnidirectional reflector is formed by the stacked structure of the first LED stack 423 having a relatively high refractive index, the insulating layer 427 having a relatively low refractive index, and the reflective layer 425b. The reflective layer 425b covers more than 50% of the area of ​​the first LED stack 423 or most of the area of ​​the first LED stack 423, thereby improving the light-emitting efficiency.

[0578] The ohmic contact layer 425a and the reflective layer 425b may be metal layers containing gold (Au). The ohmic contact layer 425a may be formed of, for example, an Au-Zn alloy or an Au-Be alloy. The reflective layer 425b may be formed of a metal such as Al, Ag, or Au that has a relatively high reflectance for light, such as red light, generated from the first LED stack 423. In particular, Au may have a relatively low reflectance for light, such as green light or blue light, generated from the second LED stack 433 and the third LED stack 443, thereby reducing optical interference due to optical absorption of light generated from the second and third LED stacks 433 and 443 and traveling toward the support substrate 451.

[0579] The insulating layer 427 is interposed between the support substrate 451 and the first LED stack 423 and has an opening exposing the first LED stack 423. The ohmic contact layer 425a is connected to the first LED stack 423 within the opening of the insulating layer 427.

[0580] The ohmic electrode 426 forms ohmic contact with the first conductive type semiconductor layer 423a of the first LED stack 423. The ohmic electrode 426 is disposed on the first conductive type semiconductor layer 423a exposed by partially removing the second conductive type semiconductor layer 423b. Although a single ohmic electrode 426 is shown in FIG. 51 , multiple ohmic electrodes 426 are arranged in multiple regions on the support substrate 451. The ohmic electrode 426 is formed of, for example, an Au—Te alloy or an Au—Ge alloy.

[0581] The second insulating layer 428 is interposed between the support substrate 425 and the reflective electrode 425, and covers the reflective electrode 425. The second insulating layer 428 has an opening through which the ohmic electrode 426 is exposed.

[0582] The interconnection line 429 is interposed between the second insulating layer 428 and the support substrate 451, and is connected to the ohmic electrode 426 through an opening in the second insulating layer 428. The interconnection line 429 can connect multiple ohmic electrodes 426 to each other on the support substrate 451.

[0583] The second-p transparent electrode 435 forms an ohmic contact with the second conductivity type semiconductor layer 433b, i.e., the p-type semiconductor layer, of the second LED stack 433. The second-p transparent electrode 435 is composed of a metal layer or a conductive oxide layer that is transparent to red and green light.

[0584] In addition, the third-p transparent electrode 445 forms an ohmic contact with the second conductivity type semiconductor layer 443b, i.e., the p-type semiconductor layer, of the third LED stack 443. The third-p transparent electrode 445 is composed of a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0585] The reflective electrode 425, the second p-transparent electrode 435 and the third p-transparent electrode 445 can assist current spreading through ohmic contact with the p-type semiconductor layer of each LED stack.

[0586] The first color filter 437 may be interposed between the first LED stack 423 and the second LED stack 433. In addition, the second color filter 447 may be interposed between the second LED stack 433 and the third LED stack 443. The first color filter 437 transmits light generated from the first LED stack 423 while reflecting light generated from the second LED stack 433. The second color filter 447 transmits light generated from the first and second LED stacks 423 and 433 while reflecting light generated from the third LED stack 443. As a result, the light generated from the first LED stack 423 is emitted to the outside via the second LED stack 433 and the third LED stack 443, and the light generated from the second LED stack 433 is emitted to the outside via the third LED stack 443. In addition, the light-emitting diode stack can prevent light generated from the second LED stack 433 from entering the first LED stack 423, or can prevent light generated from the third LED stack 443 from entering the second LED stack 433, thereby preventing light loss.

[0587] In some demonstrative embodiments, the first color filter 437 can reflect the light generated from the third LED stack 443 .

[0588] The first and second color filters 437 and 447 may be, for example, low-pass filters that allow light to pass through them in a low-frequency band (i.e., a long-wavelength band), band-pass filters that allow light to pass through them in a predetermined wavelength band, or band-stop filters that prevent light from passing through them in a predetermined wavelength band. In particular, each of the first and second color filters 437 and 447 can be formed by alternately stacking insulating layers having different refractive indices. For example, each of the first and second color filters 437 and 447 can be formed by alternately stacking TiO2 and SiO2 layers, Ta2O5 and SiO2 layers, Nb2O5 and SiO2 layers, HfO2 and SiO2 layers, or ZrO2 and SiO2 layers. The first and / or second color filters 437 and 447 can also include a distributed Bragg reflector (DBR). A distributed Bragg reflector can be formed by alternately stacking insulating layers having different refractive indices. At the same time, the stopband of the distributed Bragg reflector can be controlled by adjusting the thickness of the TiO2 and SiO2 layers.

[0589] The first bonding layer 453 bonds the first LED stack 423 to the support substrate 451. As shown, the interconnection lines 429 may be adjacent to the first bonding layer 453. Alternatively, the interconnection lines 429 may be disposed below some regions of the second insulating layer 428 such that regions of the second insulating layer 428 that do not have the interconnection lines 429 formed thereon are adjacent to the first bonding layer 453. The first bonding layer 453 may be light-transmitting or opaque. In particular, a bonding layer formed of a light-absorbing black epoxy resin is used as the first bonding layer 453, thereby improving the contrast of the display device.

[0590] The second bonding layer 455 couples the second LED stack 433 to the first LED stack 423. As shown, the second bonding layer 455 may be adjacent to the first LED stack 423 and the first color filter 437. The ohmic electrode 426 may be covered by the second bonding layer 455. The second bonding layer 455 transmits light generated from the first LED stack 423. The second bonding layer 455 may be formed of, for example, optically transparent spin-on-glass (SOG).

[0591] The third bonding layer 457 bonds the third LED stack 443 to the second LED stack 433. As shown, the third bonding layer 457 may be adjacent to the second LED stack 433 and the second color filter 447. However, it should be understood that the present disclosure is not limited thereto. For example, a transparent conductive layer may be disposed on the second LED stack 433. The third bonding layer 457 transmits light generated from the first LED stack 423 and the second LED stack 433. The third bonding layer 457 may be formed, for example, of light-transmitting spin-on glass.

[0592] In this exemplary embodiment, the first to third bonding layers 453, 455, and 457 are formed of SOG. However, it should be understood that the present disclosure is not limited thereto, and the first to third bonding layers can be formed of other transparent organic or inorganic materials. Examples of organic materials include SU...

Claims

1. a first LED stack; a second LED stack disposed on the first LED stack; a third LED stack disposed on the second LED stack; and a reflective electrode disposed below the first LED stack; a first insulating layer covering side surfaces of the first LED stack, the second LED stack, and the third LED stack; Equipped with each of the first LED stack, the second LED stack, and the third LED stack includes a first-type semiconductor layer, a second-type semiconductor layer, and an active layer disposed between the first-type semiconductor layer and the second-type semiconductor layer; the first-type semiconductor layers of the first LED stack, the second LED stack, and the third LED stack are electrically connected to the reflective electrode; a first insulating layer extending continuously on side surfaces of the first LED stack, the second LED stack, and the third LED stack, the first insulating layer being a distributed Bragg reflector;

2. Further comprising a substrate; 10. The light emitting device of claim 1, wherein the substrate exposed by the first LED stack is covered with the first insulating layer.

3. The light emitting device of claim 1 , wherein the first LED stack, the second LED stack, and the third LED stack each emit light having a different peak wavelength from each other.

4. 4. The light emitting device of claim 3, further comprising a second bonding layer disposed between the first LED stack and the second LED stack, the second bonding layer being a transparent organic insulating layer.

5. The light emitting device of claim 3 , further comprising a third bonding layer disposed between the second LED stack and the third LED stack, the third bonding layer being a transparent organic insulating layer.

6. 10. The light emitting device of claim 1, wherein the first LED stack includes a first surface facing the second LED stack and a second surface opposite the first surface, the first surface including a roughened surface.

7. 7. The light emitting device of claim 6, wherein the third LED stack includes a first surface facing the second LED stack and a second surface opposite the first surface, the second surface including a roughened surface.

8. 8. The light-emitting device of claim 7, wherein the first LED stack is in contact with a first electrode, the second LED stack is in contact with a second electrode, and the third LED stack is in contact with a third electrode, and the second electrode and the third electrode are optically transparent.

9. The light emitting device of claim 8 , wherein the third electrode is disposed on the first surface of the third LED stack.

10. The light emitting device of claim 1 , wherein each of the first LED stack, the second LED stack, and the third LED stack is controlled independently of each other.

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