Red semiconductor light-emitting device for display pixel, and display apparatus comprising same

Abstract

A red semiconductor light-emitting device for a display pixel, according to an embodiment, comprises: a first semiconductor light-emitting structure including a first conductive-type first semiconductor layer, a first active layer disposed on the first conductive-type first semiconductor layer, and a second conductive-type second semiconductor layer disposed on the first active layer; a tunnel junction structure disposed on the first semiconductor light-emitting structure; and a second semiconductor light-emitting structure, which is disposed on the tunnel junction structure and has a second active layer, wherein the second conductive-type second semiconductor layer includes a second conductive-type second-1 semiconductor layer and a second conductive-type second-2 semiconductor layer, and the doping concentration of the second conductive-type second-1 semiconductor layer can be different from the doping concentration of the second conductive-type second-2 semiconductor layer.

Description

Red semiconductor light-emitting element for display pixels and display device including the same

[0001] The present invention relates to a red semiconductor light-emitting element for a display pixel and a display device including the same.

[0002] Large-area displays include liquid crystal displays (LCDs), OLED displays, and micro-LED displays.

[0003] A micro-LED display is a display that uses micro-LEDs, which are semiconductor light-emitting elements with a diameter or cross-sectional area of ​​100㎛ or less, as display elements.

[0004] Micro-LED displays use semiconductor light-emitting diodes (micro-LEDs) as display elements, so they have superior performance in many characteristics, including contrast ratio, response speed, color reproducibility, viewing angle, brightness, resolution, lifespan, luminous efficiency, and brightness.

[0005] In particular, micro-LED displays have the advantage of being able to freely adjust the size and resolution by separating and combining the screen in a modular manner, and of being able to implement a flexible display.

[0006]

[0007] However, large-scale micro-LED displays require millions or more micro-LEDs, which poses a technical challenge in quickly and accurately transferring micro-LEDs to the display panel.

[0008] Recently developed transfer technologies include the pick and place process, the laser lift-off method, and the self-assembly method.

[0009] Among these, the self-assembly method is advantageous for implementing large-screen display devices, as it is a method in which semiconductor light-emitting elements find their own assembly positions within a fluid.

[0010] Recently, U.S. Patent No. 9,825,202 presented a micro-LED structure suitable for self-assembly, but research on the technology for manufacturing displays through self-assembly of micro-LEDs is still insufficient.

[0011] In particular, in the case of rapidly transferring millions or more semiconductor light-emitting elements to a large display in the prior art, there is a technical problem that although the transfer speed can be improved, the transfer error rate can increase, resulting in a lower transfer yield.

[0012] Meanwhile, a self-assembly transfer process using dielectrophoresis (DEP) is being attempted in related technologies, but there is a problem of low self-assembly rate due to non-uniformity of DEP force.

[0013]

[0014] Meanwhile, according to undisclosed internal technology, self-assembly of red (R) micro LED chips, green (G) micro LED chips, and blue (B) LED chips using DEP force is being studied.

[0015] In the case of micro red LED chips, due to their fast mobility compared to blue LEDs and green LEDs, carrier leakage is severe at low initial currents, which causes a decrease in chip brightness, resulting in increased power consumption and a decrease in color reproducibility of the micro LED.

[0016] Meanwhile, internal technology is researching a tandem-structured micro LED with two active layers to improve the low brightness of the Red chip. However, the luminous efficiency of the upper and lower active layers in the tandem-structured micro LED is not uniform, and the luminous efficiency of the lower active layer is reduced.

[0017] One of the technical challenges of the embodiment is to prevent the optical efficiency of the lower active layer from being reduced in a tandem structure having two active layers.

[0018] Additionally, one of the technical challenges of the embodiment is to improve the electrical problem of the hole barrier.

[0019] Additionally, one of the technical challenges of the embodiment is to prevent the lower active layer from being damaged during the growth of the upper active layer.

[0020] In addition, one of the technical challenges of the present invention is to provide a red semiconductor light-emitting element for a display pixel that improves brightness without causing problems of increased power consumption or decreased color reproducibility, and a display device including the same.

[0021] The technical problems of the embodiment are not limited to those described in this article, but include those that can be understood through the description of the invention.

[0022] A red semiconductor light-emitting element for a display pixel according to an embodiment includes a first semiconductor light-emitting structure including a first conductive first semiconductor layer, a first active layer disposed on the first conductive first semiconductor layer, and a second conductive second semiconductor layer disposed on the first active layer; a tunnel junction structure disposed on the first semiconductor light-emitting structure; and a second semiconductor light-emitting structure disposed on the tunnel junction structure and having a second active layer; wherein the second conductive second semiconductor layer includes a second conductive 2-1 semiconductor layer and a second conductive 2-2 semiconductor layer, and doping concentrations of the second conductive 2-1 semiconductor layer and the second conductive 2-2 semiconductor layer may be different.

[0023] Additionally, in the embodiment, the second conductive type 2-1 semiconductor layer may be adjacent to the first active layer, and the second conductive type 2-2 semiconductor layer may be adjacent to the tunnel junction structure.

[0024] Additionally, in the embodiment, the doping concentration of the second conductive type 2-1 semiconductor layer may be lower than the doping concentration of the second conductive type 2-2 semiconductor layer.

[0025] Additionally, in the embodiment, the doping concentration of the second conductive type 2-1 semiconductor layer may be 2.0E+17 to 3.5E+17, and the doping concentration of the second conductive type 2-2 semiconductor layer may be 3.5E+17 to 7.5E+17.

[0026] Additionally, in the embodiment, the thickness of the second conductive type 2-2 semiconductor layer may be within one to three times the thickness of the second conductive type 2-1 semiconductor layer.

[0027] Additionally, in the embodiment, the tunnel junction structure may include a first conductive type second tunnel junction layer and a first conductive type second tunnel junction layer disposed on the second conductive type first tunnel junction layer.

[0028] In addition, in the embodiment, the second challenge type first tunnel junction layer is 1X1019 atoms / cm 3 It may include a p-type AlGaAs layer doped to a concentration higher than that of the p-type AlGaAs layer.

[0029] In addition, in the embodiment, the first challenge type second tunnel junction layer is 1X10 19 atoms / cm 3 It may include an n-type GaInP layer doped with a concentration greater than or equal to the concentration.

[0030] In addition, in the embodiment, the tunnel junction structure further includes a second conductive third tunnel junction layer disposed below the second conductive first tunnel junction layer, and the second conductive third tunnel junction layer is 1X10 19 atoms / cm 3 It may include a p-type GaAs layer doped with a concentration greater than or equal to the concentration.

[0031] In addition, in the embodiment, the first semiconductor light-emitting structure further includes a second conductive fifth semiconductor layer disposed between the tunnel junction structure and the second conductive second semiconductor layer, and the second conductive fifth semiconductor layer comprises p-(Al x Ga 1-x ) y In 1-y P layer (where 0.0≤x≤0.8, 0.2≤y≤0.6) may be included.

[0032] In addition, in the embodiment, the first semiconductor light-emitting structure further includes a second conductive sixth semiconductor layer disposed between the tunnel junction structure and the second conductive fifth semiconductor layer, and the second conductive sixth semiconductor layer comprises p-(Al x1 Ga 1-x1 ) y In 1-y It includes a P layer (wherein 0.0≤x1≤0.8, 0.2≤y≤0.6), and the composition of Al in the second conductive sixth semiconductor layer can be graded.

[0033] According to a red semiconductor light-emitting element for a display pixel according to an embodiment and a display device including the same, by configuring a second conductive second semiconductor layer in a first light-emitting structure as a plurality of layers according to dopant concentration, there is a technical effect of preventing the dopant from diffusing into a lower active layer, thereby improving the light-emitting efficiency of the lower active layer in a tandem structure.

[0034] In addition, the embodiment has a technical effect of improving the uniformity of light intensity according to wavelength in a red semiconductor light-emitting device.

[0035] In addition, the embodiment has a technical effect of enabling high brightness by enabling red wavelength light emission from two active layers by including a first semiconductor light emitting structure, a second semiconductor light emitting structure, and a tunnel junction structure.

[0036] In addition, the embodiment has a technical effect of improving the power consumption of the LED display by more than 11.2% while obtaining the same brightness increase effect as applying two red semiconductor light-emitting elements.

[0037] In addition, since the embodiment has a second conductive fifth semiconductor layer between the tunnel junction structure and the first semiconductor light-emitting structure, it is possible to improve an electrical problem of a hole barrier (HB) that occurs when a hole moving through the tunnel junction cannot move smoothly due to an electrical barrier generated in a heterojunction region.

[0038] In addition, the embodiment has a technical effect that can further improve the electrical problem of the hole barrier (HB) by further including a second conductive sixth semiconductor layer in which the composition of Al is graded.

[0039] The technical effects of the embodiments are not limited to those described in this article, but include those that can be understood through the description of the invention.

[0040] Figure 1 is an exemplary diagram of a living room of a house in which a display device according to an embodiment is placed.

[0041] Figure 2 is an enlarged view of the first panel area in the display device of Figure 1.

[0042] Fig. 3 is a cross-sectional view along line B1-B2 of area A2 of Fig. 2.

[0043] Fig. 4 is an exemplary diagram showing a light-emitting element according to an embodiment being assembled on a substrate by a self-assembly method.

[0044] Figure 5 is a graph showing the luminescence intensity according to wavelength of a semiconductor light-emitting element for a display pixel being studied in internal technology.

[0045] Fig. 6 is a cross-sectional view of a red semiconductor light-emitting element for a display pixel according to the first embodiment.

[0046] Fig. 7 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting device according to the second embodiment.

[0047] Fig. 8 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting device according to the third embodiment.

[0048] Fig. 9 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting device according to the fourth embodiment.

[0049] Fig. 10 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting device according to the fifth embodiment.

[0050] Fig. 11 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting device according to the sixth embodiment.

[0051] Fig. 12 is a graph showing the luminescence intensity according to wavelength in a red semiconductor light-emitting device to which an embodiment is applied.

[0052] Hereinafter, embodiments disclosed in the present specification will be described in detail with reference to the attached drawings. The suffixes "module" and "part" used in the following description for components are given or used interchangeably for the sake of ease of writing the specification, and do not in themselves have distinct meanings or roles. In addition, the attached drawings are intended to facilitate easy understanding of the embodiments disclosed in the present specification, and the technical ideas disclosed in the present specification are not limited by the attached drawings. In addition, when an element such as a layer, region, or substrate is referred to as existing "on" another element, this includes that it may be directly on the other element, or that other intermediate elements may exist therebetween.

[0053] The display devices described in this specification may include digital TVs, mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, slate PCs, tablet PCs, Ultra-Books, desktop computers, and the like. However, the configuration according to the embodiments described in this specification may also be applied to devices capable of displaying, even if they are new product types developed in the future.

[0054]

[0055] A light-emitting element and a display device including the same according to the following embodiment are described.

[0056] FIG. 1 illustrates a living room of a house in which a display device (100) according to an embodiment is placed.

[0057] The display device (100) of the embodiment can display the status of various electronic products such as a washing machine (101), a robot vacuum cleaner (102), and an air purifier (103), and can communicate with each electronic product based on IOT and control each electronic product based on user setting data.

[0058] A display device (100) according to an embodiment may include a flexible display manufactured on a thin and flexible substrate. The flexible display can be bent or rolled like paper while maintaining the characteristics of a conventional flat panel display.

[0059] In a flexible display, visual information can be realized by independently controlling the light emission of unit pixels arranged in a matrix form. A unit pixel refers to the smallest unit for realizing a single color. The unit pixels of a flexible display can be realized by light-emitting elements. In an embodiment, the light-emitting elements may be micro-LEDs or nano-LEDs, but are not limited thereto.

[0060]

[0061] Figure 2 is an enlarged view of the first panel area (A1) in the display device of Figure 1.

[0062] According to FIG. 2, the display device (100) of the embodiment can be manufactured by mechanically and electrically connecting a plurality of panel areas, such as the first panel area (A1), through tiling.

[0063] The first panel area (A1) may include a plurality of light-emitting elements (150) arranged for each unit pixel (PX in FIG. 2).

[0064] For example, a unit pixel (PX) may include a first sub-pixel (PX1), a second sub-pixel (PX2), and a third sub-pixel (PX3). For example, a plurality of red light-emitting elements (150R) may be arranged in the first sub-pixel (PX1), a plurality of green light-emitting elements (150G) may be arranged in the second sub-pixel (PX2), and a plurality of blue light-emitting elements (150B) may be arranged in the third sub-pixel (PX3). The unit pixel (PX) may further include a fourth sub-pixel in which no light-emitting element is arranged, but this is not limited thereto. Meanwhile, the light-emitting element (150) may be a semiconductor light-emitting element.

[0065]

[0066] Next, Fig. 3 is a cross-sectional view along line B1-B2 of area A2 of Fig. 2.

[0067] Referring to FIG. 3, the display device (100) of the embodiment may include a substrate (200), assembly wiring (201, 202), a first insulating layer (211a), a second insulating layer (211b), a third insulating layer (206), and a plurality of light-emitting elements (150).

[0068] The assembly wiring may include a first assembly wiring (201) and a second assembly wiring (202) that are spaced apart from each other. The first assembly wiring (201) and the second assembly wiring (202) may be provided to generate a dielectrophoretic force for assembling the light emitting element (150). In addition, the first assembly wiring (201) and the second assembly wiring (202) may be electrically connected to electrodes of the light emitting element to function as electrodes of the display panel.

[0069] The assembly wiring (201, 202) may be formed of a light-transmitting electrode (ITO) or may include a metal material with excellent electrical conductivity. For example, the assembly wiring (201, 202) may be formed of at least one of titanium (Ti), chromium (Cr), nickel (Ni), aluminum (Al), platinum (Pt), gold (Au), tungsten (W), molybdenum (Mo), or an alloy thereof.

[0070] A first insulating layer (211a) may be disposed between the first assembly wiring (201) and the second assembly wiring (202), and a second insulating layer (211b) may be disposed on the first assembly wiring (201) and the second assembly wiring (202). The first insulating layer (211a) and the second insulating layer (211b) may be an oxide film, a nitride film, or the like, but are not limited thereto.

[0071]

[0072] The light-emitting element (150) may include a red light-emitting element (150), a green light-emitting element (150G), and a blue light-emitting element (150B0) to form a unit pixel (sub-pixel), but is not limited thereto, and may also include a red phosphor and a green phosphor to implement red and green, respectively.

[0073] The substrate (200) may be formed of glass or polyimide. In addition, the substrate (200) may include a flexible material such as polyethylene naphthalate (PEN) or polyethylene terephthalate (PET). In addition, the substrate (200) may be a transparent material, but is not limited thereto.

[0074] The third insulating layer (206) may include an insulating and flexible material such as polyimide, PEN, PET, etc., and may be formed integrally with the substrate (200) to form a single substrate.

[0075] The third insulating layer (206) may be a conductive adhesive layer having adhesive properties and conductivity, and the conductive adhesive layer may be flexible to enable a flexible function of the display device. For example, the third insulating layer (206) may be a conductive adhesive layer such as an anisotropic conductive film (ACF) or an anisotropic conductive medium, a solution containing conductive particles, etc. The conductive adhesive layer may be a layer that is electrically conductive in a direction vertical to the thickness, but electrically insulating in a direction horizontal to the thickness.

[0076] The third insulating layer (206) may include an assembly hole (203) into which a light-emitting element (150) is inserted. Therefore, during self-assembly, the light-emitting element (150) can be easily inserted into the assembly hole (203) of the third insulating layer (206). The assembly hole (203) may be referred to as an insertion hole, a fixing hole, an alignment hole, or the like.

[0077] The gap between the assembly wiring (201, 202) is formed to be smaller than the width of the light emitting element (150) and the width of the assembly hole (203), so that the assembly position of the light emitting element (150) can be fixed more precisely using an electric field.

[0078] A third insulating layer (206) is formed on the assembly wiring (201, 202) to protect the assembly wiring (201, 202) from the fluid (1200) and prevent leakage of current flowing in the assembly wiring (201, 202). The third insulating layer (206) may be formed as a single layer or multiple layers of an inorganic insulator such as silica or alumina or an organic insulator.

[0079] Additionally, the third insulating layer (206) may include an insulating and flexible material such as polyimide, PEN, PET, etc., and may be formed integrally with the substrate (200) to form a single substrate.

[0080] The third insulating layer (206) may be an adhesive insulating layer or a conductive adhesive layer having conductivity. The third insulating layer (206) may be flexible, thereby enabling a flexible function of the display device.

[0081] The third insulating layer (206) has a partition wall, and an assembly hole (203) can be formed by this partition wall. For example, when forming the substrate (200), a part of the third insulating layer (206) is removed, so that each of the light emitting elements (150) can be assembled into the assembly hole (203) of the third insulating layer (206).

[0082] An assembly hole (203) is formed in the substrate (200) to which light-emitting elements (150) are coupled, and the surface where the assembly hole (203) is formed can come into contact with a fluid (1200). The assembly hole (203) can guide the exact assembly position of the light-emitting elements (150).

[0083] Meanwhile, the assembly hole (203) may have a shape and size corresponding to the shape of the light-emitting element (150) to be assembled at the corresponding position. Accordingly, it is possible to prevent another light-emitting element from being assembled in the assembly hole (203) or multiple light-emitting elements from being assembled.

[0084]

[0085] FIG. 4 is a drawing showing an example in which a light-emitting element according to an embodiment is assembled on a substrate by a self-assembly method, and the self-assembly method of the light-emitting element is explained with reference to the drawings.

[0086] The substrate (200) may be a panel substrate of a display device. In the following description, the substrate (200) is described as a panel substrate of a display device, but the embodiment is not limited thereto.

[0087] Referring to FIG. 4, a plurality of light-emitting elements (150) may be placed in a chamber (1300) filled with a fluid (1200). The fluid (1200) may be, but is not limited to, water such as ultrapure water. The chamber may be referred to as a tank, a container, a vessel, or the like.

[0088] After this, the substrate (200) can be placed on the chamber (1300). Depending on the embodiment, the substrate (200) can also be introduced into the chamber (1300).

[0089] As shown in FIG. 3, a pair of assembly wirings (201, 202) corresponding to each light emitting element (150) to be assembled can be arranged on the substrate (200).

[0090] Referring to FIG. 4, after the substrate (200) is placed, an assembly device (1100) including a magnetic body can move along the substrate (200). For example, a magnet or an electromagnet can be used as the magnetic body. The assembly device (1100) can move in contact with the substrate (200) to maximize the area affected by the magnetic field within the fluid (1200). Depending on the embodiment, the assembly device (1100) may include a plurality of magnetic bodies or may include magnetic bodies of a size corresponding to that of the substrate (200). In this case, the movement distance of the assembly device (1100) may be limited within a predetermined range.

[0091] By the magnetic field generated by the assembly device (1100), the light emitting element (150) within the chamber (1300) can move toward the assembly device (1100).

[0092] The light emitting element (150) may move toward the assembly device (1100) and enter the assembly hole (203) by the dielectric electrophoretic force (DEP force) to come into contact with the substrate (200).

[0093] Specifically, the assembly wiring (201, 202) forms an electric field by an externally supplied power source, and a dielectric force can be formed between the assembly wiring (201, 202) by this electric field. The light-emitting element (150) can be fixed to the assembly hole (203) on the substrate (200) by this dielectric force.

[0094] The light emitting element (150) in contact with the substrate (200) can be prevented from being detached by the movement of the assembly device (1100) due to the electric field applied by the assembly wiring (201, 202) formed on the substrate (200). According to an embodiment, the time required for each of the light emitting elements (150) to be assembled on the substrate (200) can be drastically shortened by the self-assembly method using the electromagnetic field described above, so that a large-area, high-pixel display can be implemented more quickly and economically.

[0095] At this time, a predetermined solder layer (not shown) is formed between the light-emitting element (150) assembled on the assembly hole (203) of the substrate (200) and the assembly electrode, thereby improving the bonding strength of the light-emitting element (150).

[0096] Next, a molding layer (not shown) may be formed in the assembly hole (203) of the substrate (200). The molding layer may be a light-transmitting resin or a resin containing a reflective material or a scattering material.

[0097]

[0098] Figure 5 is a graph showing the luminescence intensity according to wavelength of a semiconductor light-emitting element for a display pixel being studied in internal technology.

[0099] Referring to Fig. 5, the semiconductor light-emitting element for a display pixel being studied internally may have a tandem structure in which a second light-emitting structure is formed on a first light-emitting structure. The first active layer (MQW1) and the second active layer (MQW2) may emit light at different wavelengths.

[0100]

[0101] Meanwhile, in the tandem structure micro LED of the comparative technology, there is no recognition of problems such as uniformity of luminous efficiency for the upper and lower active layers.

[0102] On the other hand, in the internal technology, while studying a tandem structure micro LED with two active layers to improve the low brightness of the Red chip, we discovered through in-depth research the problem of the lower luminous efficiency of the lower active layer being reduced due to the non-uniform luminous efficiency of the upper and lower active layers.

[0103]

[0104] In addition, through internal technical research, the cause of the problem was discovered through in-depth research, which revealed that the first active layer of the first light-emitting structure was damaged during the growth process of the second light-emitting structure after the first light-emitting structure was formed.

[0105] In detail, there is a problem that the dopant of the p-type semiconductor layer of the first light-emitting structure diffuses into the first active layer due to the high process temperature for growing the second light-emitting structure, thereby reducing the light-emitting efficiency of the first active layer. Accordingly, there is a problem that the overall light-emitting intensity of the semiconductor light-emitting device decreases, and the difference in light-emitting intensity between the first active layer and the second active layer increases.

[0106]

[0107] Hereinafter, an embodiment for solving the above problem will be described.

[0108] Fig. 6 is a cross-sectional view of a red semiconductor light-emitting device (250A) for a display pixel according to the first embodiment. Hereinafter, the “red semiconductor light-emitting device for a display pixel” will be abbreviated as “red semiconductor light-emitting device.” The red semiconductor light-emitting device according to the embodiment

[0109] A red semiconductor light-emitting device (250A) according to the first embodiment may include a first semiconductor light-emitting structure (251), a second semiconductor light-emitting structure (252), and a tunnel junction structure (250T) disposed between the first and second semiconductor light-emitting structures (251, 252).

[0110] In addition, the first embodiment may include a first electrode layer (254n) disposed on the lower side of the first semiconductor light-emitting structure (251) and a second electrode layer (254p) disposed on the upper side of the second semiconductor light-emitting structure (252). The first electrode layer (254n) may include a magnetic metal such as nickel (Ni). The second electrode layer (254p) may include a light-transmitting ohmic layer such as ITO, IZO, ZnO, etc., but is not limited thereto. In addition, the first embodiment may further include a passivation layer (256) surrounding the first and second semiconductor light-emitting structures (251, 252). The passivation layer (256) may include an inorganic insulator such as silica, alumina, etc., but is not limited thereto.

[0111] The red semiconductor light-emitting device (250A) according to the first embodiment may be an AlGaInP-based light-emitting diode and may emit light with a wavelength within a range of about 570 nm to about 640 nm. The wavelength may be determined by the band gap energy of the light-emitting diode. For example, the band gap size may be adjusted by changing the composition ratio of Al and Ga, and the wavelength may become shorter as the composition ratio of Al increases.

[0112] In addition, the first semiconductor light-emitting structure (251) may include a first conductive first semiconductor layer (251n), a first active layer (251a) disposed on the first conductive first semiconductor layer (251n), and a second conductive second semiconductor layer (251p) disposed on the first active layer. In addition, the first semiconductor light-emitting structure (251) may further include a diffusion barrier film (not shown) disposed between the second conductive second semiconductor layer (251p) and the first active layer (251a).

[0113] The above first semiconductor light emitting structure (251) is (Al x Ga 1-x ) y In 1-yIt may include a P layer (wherein 0.0≤x≤1.0, 0.01≤y≤0.9), and the first conductive first semiconductor layer (251n) may be doped with an N-type dopant, and the second conductive second semiconductor layer (251p) may be doped with a P-type dopant, but is not limited thereto.

[0114] For example, the N-type dopant may be Si or Te, and the P-type dopant may be, but is not limited to, Mg or C (carbon).

[0115] The above first conductive type first semiconductor layer (251n) may include, but is not limited to, a high-concentration first conductive type 1-1 semiconductor layer (not shown) and a low-concentration first conductive type 1-2 semiconductor layer (not shown).

[0116] For example, the above 1-1 semiconductor layer is n + -AlGaInP layer may be included, and the first and second semiconductor layers may include an n-GaP layer, but are not limited thereto.

[0117] In addition, in the first embodiment, the second semiconductor light-emitting structure (252) may include a first conductive third semiconductor layer (252n), a second active layer (252a) disposed on the first conductive third semiconductor layer (252n), and a second conductive fourth semiconductor layer (252p) disposed on the second active layer (252a).

[0118] The above second semiconductor light emitting structure (252) is (Al x Ga 1-x ) y In 1-yIt may include a P layer (wherein 0.0≤x≤1.0, 0.01≤y≤0.9), and the first conductive third semiconductor layer (252n) may be doped with an N-type dopant, and the second conductive fourth semiconductor layer (252p) may be doped with a P-type dopant, but is not limited thereto. For example, the N-type dopant may be Si or Te, and the P-type dopant may be Mg or C (carbon), but is not limited thereto.

[0119] In addition, the second conductive type 4th semiconductor layer (252p) may include, but is not limited to, a low-concentration second conductive type 4-1 semiconductor layer (not shown) and a high-concentration second conductive type 4-2 semiconductor layer (not shown). For example, the 4-1 semiconductor layer may include a p-AlGaInP layer, and the 4-2 semiconductor layer may include a p +- It may include, but is not limited to, a GaP layer.

[0120] Meanwhile, in the embodiment, the second conductive second semiconductor layer (251p) may include a second conductive second-first semiconductor layer (251p1) and a second conductive second-second semiconductor layer (251p2). The second conductive second-first semiconductor layer (251p1) may be adjacent to the first active layer (251a) of the first semiconductor light-emitting structure (251). In addition, the second conductive second-second semiconductor layer (251p2) may be adjacent to the tunnel junction structure (250T). The dopants of the second conductive second-first semiconductor layer (251p1) and the second conductive second-second semiconductor layer (251p2) may be the same material, but are not limited thereto.

[0121] At this time, the doping concentration of the second conductive type 2-1 semiconductor layer (251p1) may be lower than the doping concentration of the second conductive type 2-2 semiconductor layer (251p2).

[0122] Accordingly, the embodiment has a special technical effect of reducing the problem of dopants of the second conductive second semiconductor layer diffusing into the first active layer by forming the doping concentration of the second conductive second-1 semiconductor layer adjacent to the first semiconductor light-emitting structure in the second conductive second semiconductor layer lower than the doping concentration of the second conductive second-2 semiconductor layer, thereby improving the light-emitting efficiency of the first active layer.

[0123]

[0124] Fig. 7 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting device (250B) according to a second embodiment. Referring to Fig. 7, the second conductive semiconductor layer (251p) of the first semiconductor light-emitting structure (251) may be doped with a P-type dopant. For example, it may be Mg or C (carbon), but is not limited thereto.

[0125] The second conductive type second semiconductor layer (251p) may include a second conductive type 2-1 semiconductor layer (251p1) and a second conductive type 2-2 semiconductor layer (251p2). The doping concentration of the second conductive type 2-1 semiconductor layer (251p1) may be lower than the doping concentration of the second conductive type 2-2 semiconductor layer (251p2). In detail, the doping concentration of the second conductive type 2-2 semiconductor layer (251p2) is 3.5E+17 to 7.5E+17 (atoms / cm 3 ) can be in the range (but E+17=10 17 ) In addition, the doping concentration of the second challenge type 2-1 semiconductor layer (251p1) is 2.0E+17 to 3.5E+17 (atoms / cm 3 ) may be in the range.

[0126] The doping concentration of the second conductive type 2-2 semiconductor layer (251p2) may correspond to the doping concentration of the second conductive type 4 semiconductor layer, but is not limited thereto. In addition, the doping concentration of the second conductive type 2-1 semiconductor layer (251p1) may be lower than the doping concentration of the second conductive type 4 semiconductor layer.

[0127] Accordingly, the second conductive type 2-2 semiconductor layer (251p2) adjacent to the tunnel junction structure (250T) has a high doping concentration so as to sufficiently secure carriers for electrical performance, and the second conductive type 2-1 semiconductor layer (251p1) adjacent to the first active layer has a relatively low doping concentration so as to suppress diffusion of dopants into the first active layer. Therefore, the second embodiment has a technical effect of improving the luminous efficiency of the first active layer.

[0128] Additionally, the thickness of the second conductive type 2-2 semiconductor layer (251p2) may be one to three times the thickness of the second conductive type 2-1 semiconductor layer (251p1).

[0129] Accordingly, the second conductive type 2-2 semiconductor layer (251p2) has a thickness greater than or equal to the thickness of the second conductive type 2-1 semiconductor layer (251p1), thereby sufficiently securing carriers and improving electrical performance, and the second conductive type 2-1 semiconductor layer (251p1) is formed relatively thin, thereby preventing diffusion of dopants, thereby providing a composite technical effect of improving the luminous efficiency of the first active layer.

[0130]

[0131] Fig. 8 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting device (250C) according to the third embodiment. In the third embodiment, the tunnel junction structure (250T) is 1X10 19 atoms / cm 3 It can be doped at a high concentration above the concentration.

[0132] The above tunnel junction structure (250T) may include a second conductive type first tunnel junction layer (250Tp) and a first conductive type second tunnel junction layer (250Tn). The second conductive type first tunnel junction layer (250Tp) may be positioned below the first conductive type second tunnel junction layer (250Tn).

[0133] The above second challenge type first tunnel junction layer (250Tp) may include a high concentration AlGaAs layer.

[0134] For example, the second challenge type first tunnel junction layer (250Tp) has 1X10 carbon (C) 19 atoms / cm 3 p doped at a high concentration above the concentration ++- It may contain an AlGaAs layer.

[0135] Next, the first conductive second tunnel junction layer (250Tn) may include a high-concentration GaInP layer. For example, the first conductive second tunnel junction layer (250Tn) may include 1X10 Si. 19 atoms / cm 3 n doped at a high concentration above the concentration ++- It may include a GaInP layer.

[0136] Accordingly, the second embodiment has a technical feature that enables high brightness implementation by including a tunnel junction structure (250T) disposed between the first semiconductor light-emitting structure (251), the second semiconductor light-emitting structure (252), and the first and second semiconductor light-emitting structures (251, 252), thereby enabling red wavelength light emission from two active layers.

[0137]

[0138] Fig. 9 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting device (250D) according to a fourth embodiment. In the fourth embodiment, the tunnel junction structure (250T) may further include a second conductive first tunnel junction layer (250Tp), a first conductive second tunnel junction layer (250Tn), and a second conductive third tunnel junction layer (250Tp2). The second conductive third tunnel junction layer (250Tp2) may be disposed below the second conductive first tunnel junction layer (250Tp).

[0139] The second conductive third tunnel junction layer (250Tp2) may include a high-concentration GaAs layer. For example, the second conductive third tunnel junction layer (250Tp2) may include 1X10 carbon (C). 19 atoms / cm 3 p doped at a high concentration above the concentration ++ -May contain a GaAs layer.

[0140] Accordingly, there is a technical feature that enables high brightness implementation by including a tunnel junction structure (250T) disposed between the first semiconductor light-emitting structure (251), the second semiconductor light-emitting structure (252) and the first and second semiconductor light-emitting structures (251, 252), thereby enabling red wavelength light emission from two active layers.

[0141] In addition, according to an example, the same brightness increase effect as applying two red semiconductor light-emitting elements is achieved while improving the power consumption of the LED display by more than 11.2% (based on full white, 300 nit).

[0142]

[0143] Fig. 10 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting device (250E) according to a fifth embodiment. The fifth embodiment may adopt the technical features of the red semiconductor light-emitting device according to the fourth embodiment. For example, the fifth embodiment may include a tunnel junction structure (250T) having a second conductive first tunnel junction layer (250Tp), a first conductive second tunnel junction layer, and a second conductive third tunnel junction layer (250Tp2).

[0144] Meanwhile, in the fifth embodiment, the first semiconductor light-emitting structure (251) disposed under the tunnel junction structure (250T) may further include a second conductive fifth semiconductor layer (265). The second conductive fifth semiconductor layer (265) may be disposed between the tunnel junction structure (250T) and the second conductive second semiconductor layer (251p).

[0145] The second challenge type fifth semiconductor layer (265) is p-(Al x Ga 1-x ) y In 1-y It may include a P layer (where 0.0≤x≤0.8, 0.2≤y≤0.6) and may be doped with Mg, but is not limited thereto.

[0146] In general, when the AlInP series layer of the phosphide series that grows as the cladding layer in the LED structure and the AlGaAs series layer of the arsenide series that forms the tunnel junction are joined, a heterojunction is formed in terms of material, but since the difference in lattice constant between the materials can be controlled by controlling the Al composition of the two layers, it is common to grow them continuously without inserting a separate interlayer layer between the joining layers.

[0147] Meanwhile, although the epitaxial growth itself does not cause a problem in the p-AlInP / AlGaAs junction despite being a junction of different materials, it was studied that a hole barrier (HB) exists between the first semiconductor light-emitting structure (251) and the tunnel junction structure (250T) according to the red semiconductor light-emitting element of the internal technology.

[0148] For example, it was studied that a hole barrier (HB) may exist due to an offset caused by a difference in bandgap energy and a difference in Fermi level of the heterogeneous materials between a tunnel junction structure (250T) requiring high concentration doping and a p-type clad layer, which is a second conductive second semiconductor layer (251p) of the first semiconductor light-emitting structure (251).

[0149] The red semiconductor light-emitting device (250B) according to the second embodiment may include a second conductive fifth semiconductor layer (265) between the tunnel junction structure (250T) and the second conductive second semiconductor layer (251p) of the first-second semiconductor light-emitting structure (251B).

[0150] There is a special technical effect that improves the electrical problem of the hole barrier (HB) that occurs when a hole moving through a tunnel junction is prevented from moving smoothly due to an electrical barrier generated in the heterojunction region.

[0151] In the field of LED technology, the p-AlInP / AlGaAs junction is a junction of different materials, but the epitaxial growth itself does not cause problems. In the field of LED technology, since the AlGaAs / AlInP heterojunction is a junction grown without an interlayer, it is not easy to notice that an electrical problem is occurring in the junction layer.

[0152]

[0153] Next, Fig. 11 is a partial cross-sectional schematic diagram of a red semiconductor light-emitting element (250F) according to the sixth embodiment. The sixth embodiment may employ the technical features of the fifth embodiment. For example, the sixth embodiment may include a fifth second-conductivity semiconductor layer between the tunnel junction structure (250T) and the second second-conductivity semiconductor layer, thereby improving the electrical problem of the hole barrier.

[0154] Referring to FIG. 11, the sixth embodiment may further include a second conductive sixth semiconductor layer (266) between the tunnel junction structure (250T) and the second conductive fifth semiconductor layer (265) of the first semiconductor light-emitting structure (251).

[0155] The second challenge type fifth semiconductor layer (265) is p-(Al x Ga 1-x ) y In 1-y It may include a P layer (where 0.0≤x≤0.8, 0.2≤y≤0.6) and may be doped with Mg, but is not limited thereto.

[0156] In addition, the second challenge type 6th semiconductor layer (266) is p-(Al x1 Ga 1-x1 ) y In 1-yIt may include a P layer (where 0.0≤x1≤0.8, 0.2≤y≤0.6) and may be doped with Mg, but is not limited thereto.

[0157] The composition of Al in the second challenge type 6 semiconductor layer (266) can be graded.

[0158] For example, in the second challenge type 6th semiconductor layer (266), the composition X1 of Al can be graded from 0.3 to 0.6 to 0.0.

[0159] Accordingly, the sixth embodiment has a special technical effect of further improving the electrical problem of the hole barrier (HB) by further including the second conductive sixth semiconductor layer (266) in which the composition of Al is graded.

[0160]

[0161] Fig. 12 is a graph showing the luminescence intensity according to wavelength in a red semiconductor light-emitting device to which an embodiment is applied. The red semiconductor light-emitting device of the embodiment may split the wavelength so that the wavelengths of light emitted from the first active layer and the second active layer may be different.

[0162] Referring to Fig. 12, the dopant of the semiconductor layer positioned between the first active layer and the tunnel junction layer is prevented from diffusing into the first active layer, thereby preventing a decrease in the luminescence efficiency of the first active layer. Accordingly, compared to Fig. 5, the luminescence intensity of the first active layer (MQW1) can be significantly improved, and the difference in luminescence intensity with respect to the second active layer (MQW2) can be reduced.

[0163] Accordingly, the embodiment has a technical effect of preventing a decrease in the luminous efficiency of the first active layer located at the bottom in a tandem structure semiconductor light-emitting device having a first active layer and a second active layer, thereby improving the luminous efficiency of the semiconductor light-emitting device, and improving the uniformity of light intensity according to wavelength.

[0164]

[0165] According to a red semiconductor light-emitting element for a display pixel according to an embodiment and a display device including the same, by configuring a second conductive second semiconductor layer in a first light-emitting structure as a plurality of layers according to dopant concentration, there is a technical effect of preventing the dopant from diffusing into a lower active layer, thereby improving the light-emitting efficiency of the lower active layer in a tandem structure.

[0166] In addition, the embodiment has a technical effect of improving the uniformity of light intensity according to wavelength in a red semiconductor light-emitting device.

[0167] In addition, the embodiment has a technical effect of enabling high brightness by enabling red wavelength light emission from two active layers by including a first semiconductor light emitting structure, a second semiconductor light emitting structure, and a tunnel junction structure.

[0168] In addition, the embodiment has a technical effect of improving the power consumption of the LED display by more than 11.2% while obtaining the same brightness increase effect as applying two red semiconductor light-emitting elements.

[0169] In addition, since the embodiment has a second conductive fifth semiconductor layer between the tunnel junction structure and the first semiconductor light-emitting structure, it is possible to improve an electrical problem of a hole barrier (HB) that occurs when a hole moving through the tunnel junction cannot move smoothly due to an electrical barrier generated in a heterojunction region.

[0170] In addition, the embodiment has a technical effect that can further improve the electrical problem of the hole barrier (HB) by further including a second conductive sixth semiconductor layer in which the composition of Al is graded.

[0171]

[0172] Although the present invention has been described above with reference to embodiments thereof, it will be readily understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

[0173] The embodiments may be applied to, but are not limited to, display devices. For example, the embodiments may be applied to, but are not limited to, a micro-LED display using an inorganic light-emitting element, an LED, as a light-emitting pixel.

Claims

1. A first semiconductor light-emitting structure including a first conductive type first semiconductor layer, a first active layer disposed on the first conductive type first semiconductor layer, and a second conductive type second semiconductor layer disposed on the first active layer; A tunnel junction structure disposed on the first semiconductor light-emitting structure; and A second semiconductor light-emitting structure is disposed on the above tunnel junction structure and includes a second active layer; The second conductive type second semiconductor layer includes a second conductive type 2-1 semiconductor layer and a second conductive type 2-2 semiconductor layer, A red semiconductor light-emitting element for a display pixel, wherein the doping concentrations of the second challenge type 2-1 semiconductor layer and the second challenge type 2-2 semiconductor layer are different.

2. In paragraph 1, The second challenge type 2-1 semiconductor layer is adjacent to the first active layer, The second challenge type 2-2 semiconductor layer is a red semiconductor light-emitting element for a display pixel, adjacent to the tunnel junction structure.

3. In paragraph 2, A red semiconductor light-emitting element for a display pixel, characterized in that the doping concentration of the second conductive type 2-1 semiconductor layer is lower than the doping concentration of the second conductive type 2-2 semiconductor layer.

4. In paragraph 3, The doping concentration of the second challenge type 2-1 semiconductor layer is 2.0E+17 to 3.5E+17, A red semiconductor light-emitting element for a display pixel, wherein the doping concentration of the second challenge type 2-2 semiconductor layer is 3.5E+17 to 7.5E+17.

5. In paragraph 2, A red semiconductor light-emitting element for a display pixel, characterized in that the thickness of the second conductive type 2-2 semiconductor layer is within one to three times the thickness of the second conductive type 2-1 semiconductor layer.

6. In paragraph 1, The above tunnel junction structure is, A red semiconductor light-emitting element for a display pixel, comprising a first conductive type second tunnel junction layer disposed on the second conductive type first tunnel junction layer and the second conductive type first tunnel junction layer.

7. In paragraph 6, The above second challenge type first tunnel junction layer is 1X10 19 atoms / cm 3 A red semiconductor light-emitting element for a display pixel, comprising a p-type AlGaAs layer doped at a concentration exceeding 100 nm.

8. In paragraph 6, The above first challenge type second tunnel junction layer is 1X10 19 atoms / cm 3 A red semiconductor light-emitting element for a display pixel, comprising an n-type GaInP layer doped with a concentration greater than or equal to 1.

9. In paragraph 6, The above tunnel junction structure is, It further includes a second challenge type third tunnel junction layer arranged below the second challenge type first tunnel junction layer, The above 2nd challenge type 3 tunnel junction layer is 1X10 19 atoms / cm 3 A red semiconductor light-emitting element for a display pixel, comprising a p-type GaAs layer doped with a concentration greater than or equal to 1.

10. In paragraph 1, The above first semiconductor light-emitting structure is, It further includes a second conductive fifth semiconductor layer disposed between the above tunnel junction structure and the second conductive second semiconductor layer, The second challenge type fifth semiconductor layer is p-(Al x Go 1-x ) y In 1-y A red semiconductor light-emitting element for a display pixel, comprising a P layer (wherein 0.0≤x≤0.8 and 0.2≤y≤0.6).

11. In paragraph 10, The above first semiconductor light-emitting structure is, It further includes a second conductive type sixth semiconductor layer arranged between the above tunnel junction structure and the second conductive type fifth semiconductor layer, The second challenge type 6 semiconductor layer is p-(Al x1 Go 1-x1 ) y In 1-y A red semiconductor light-emitting element for a display pixel, comprising a P layer (wherein 0.0≤x1≤0.8, 0.2≤y≤0.6), and wherein the composition of Al in the second conductive sixth semiconductor layer is graded.

12. A display device comprising a red semiconductor light-emitting element for a display pixel according to any one of claims 1 to 11.

Images