Light-emitting diode capable of emitting light directionally and preparation method of light-emitting diode

Abstract

The invention provides a directional light emitting light emitting diode and a preparation method thereof, and belongs to the technical field of photoelectron manufacturing. The light-emitting diode comprises a light-emitting block, a reflecting layer and a metal electrode layer, the light-emitting block is located on the surface of the metal electrode layer, the reflecting layer is located on the surface of the metal electrode layer and covers the light-emitting block, a light-emitting hole is formed in the surface, away from the metal electrode layer, of the reflecting layer, and the light-emitting block is exposed out of the light-emitting hole. According to the embodiment of the invention, the light-emitting diode can be controlled to directionally emit light at a small angle, so that the light emitted by the light-emitting diode is fully utilized, and the probability that the emitted light is absorbed is reduced, thereby improving the light extraction efficiency.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a light-emitting diode with directional light emission and a method for its fabrication. Background Technology

[0002] Micro LEDs are small in size, allowing for denser arrangement and significantly improved resolution. They also have self-emissive properties, making them superior to LCDs in terms of high brightness, high contrast, high responsiveness, and energy saving.

[0003] In related technologies, a light-emitting diode typically includes a substrate, an epitaxial layer, and electrodes. The epitaxial layer is located on the substrate, and the electrodes are located on the epitaxial layer. An external power source supplies current to the epitaxial layer through the electrodes to control the epitaxial layer to emit light.

[0004] Due to the light-emitting mechanism of LEDs, the light emitted from the epitaxial layer is disordered, meaning the light rays can emerge from any direction. This causes most of the light emitted by the LED to be absorbed by various film layers, reducing light extraction efficiency. In AR display applications, light sources are typically required to emit light at a relatively small angle. Therefore, when LEDs are used as light sources, the emitted light is difficult to fully utilize. Summary of the Invention

[0005] This disclosure provides a directional light-emitting diode and its fabrication method, which can control the light-emitting diode to emit light at a small angle, thereby fully utilizing the emitted light and reducing the probability of light absorption, thus improving light extraction efficiency. The technical solution is as follows:

[0006] On one hand, this disclosure provides a light-emitting diode, which includes: a light-emitting block, a reflective layer, and a metal electrode layer; the light-emitting block is located on the surface of the metal electrode layer, the reflective layer is located on the surface of the metal electrode layer and covers the light-emitting block, and the surface of the reflective layer away from the metal electrode layer is provided with a light-emitting hole, the light-emitting hole exposing the light-emitting block.

[0007] In one implementation of this disclosure, the surface of the metal electrode layer has an arcuate groove, and the surface of the light-emitting block near the metal electrode layer is in contact with the groove surface of the arcuate groove; the outer wall of the film layer of the reflective layer covering the light-emitting block is an arcuate surface, and the arcuate surface and the groove surface of the arcuate groove form a confocal resonant cavity.

[0008] In another implementation of this disclosure, the cross-sectional shape of the confocal resonant cavity is circular or elliptical.

[0009] In another implementation of this disclosure, the orthographic projection of the light-emitting aperture onto the surface of the metal electrode layer is located in the central region of the orthographic projection of the light-emitting block onto the surface of the metal electrode layer.

[0010] In another implementation of this disclosure, at least one light-emitting hole is provided on the surface of the reflective layer. When there are multiple light-emitting holes, the multiple light-emitting holes are arranged at intervals, and the sum of the cross-sectional areas of the multiple light-emitting holes is a first area. When there is only one light-emitting hole, the cross-sectional area of ​​the light-emitting hole is a second area, and the ratio of the first area to the second area is 0.9 to 1.1.

[0011] In another implementation of this disclosure, the light-emitting diode further includes a transparent electrode layer located on the surface of the reflective layer away from the metal electrode layer and extending into the light-emitting aperture and connected to the light-emitting block.

[0012] In another implementation of this disclosure, the thickness of the transparent electrode layer is 2,500 to 3,500 angstroms.

[0013] In another implementation of this disclosure, the transmittance of the transparent electrode layer is greater than or equal to 90%.

[0014] In another implementation of this disclosure, the reflective layer comprises a plurality of alternating layers of first material and a plurality of layers of second material, wherein the refractive indices of the first material and the second material are different.

[0015] On the other hand, this disclosure also provides a method for fabricating a light-emitting diode (LED), the method comprising: forming an epitaxial layer on a temporary substrate, the surface of the epitaxial layer having bumps, the surface of the bumps away from the temporary substrate being arc-shaped; forming a metal electrode layer on the surface of the epitaxial layer, such that the metal electrode layer covers the bumps; bonding the surface of the metal electrode layer away from the epitaxial layer to a substrate, and removing the temporary substrate; etching the epitaxial layer to form a light-emitting block, the light-emitting block including the bumps; forming a reflective layer on the surface of the metal electrode layer, such that the reflective layer covers the light-emitting block; forming a light-emitting aperture on the reflective layer, the light-emitting aperture exposing the light-emitting block; and forming a transparent electrode layer on the surface of the reflective layer away from the metal electrode layer, the transparent electrode layer extending into the light-emitting aperture and connected to the light-emitting block.

[0016] The beneficial effects of the technical solutions provided in this disclosure include at least the following:

[0017] The light-emitting diode provided in this embodiment has a light-emitting block placed on the surface of a metal electrode layer, and a reflective layer that fully covers the light-emitting block and part of the metal electrode layer to form a reflective cavity surrounding the light-emitting block, and a light-emitting hole is precisely opened at the top to expose only the light-emitting block.

[0018] In this structure, the reflective layer and the metal electrode layer together form a reflective cavity. The disordered light emitted by the light-emitting block first scatters in all directions. The light rays heading towards the reflective layer are reflected multiple times and gradually guided to the top. A small amount of light rays that propagate directly upwards are emitted directly through the light-emitting aperture. The reflective cavity can repeatedly collect and redirect stray light, ultimately allowing light rays aligned with the direction of the light-emitting aperture to be emitted efficiently. This converges the originally divergent beam into approximately parallel or small-angle light rays, effectively improving the utilization rate of small-angle light required in AR applications, while reducing the probability of emitted light being absorbed, thereby improving light extraction efficiency. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of this disclosure;

[0021] Figure 2 This is a comparative schematic diagram of a light-emitting aperture provided in an embodiment of this disclosure;

[0022] Figure 3 This is a flowchart of a method for fabricating a light-emitting diode according to an embodiment of this disclosure;

[0023] Figure 4 This is a fabrication state diagram of a light-emitting diode provided in an embodiment of this disclosure;

[0024] Figure 5 This is a fabrication state diagram of a light-emitting diode provided in an embodiment of this disclosure;

[0025] Figure 6 This is a fabrication state diagram of a light-emitting diode provided in an embodiment of this disclosure;

[0026] Figure 7 This is a fabrication state diagram of a light-emitting diode provided in an embodiment of this disclosure;

[0027] Figure 8 This is a fabrication state diagram of a light-emitting diode provided in an embodiment of this disclosure.

[0028] The markings in the diagram are explained as follows:

[0029] 10. Substrate; 11. Temporary substrate;

[0030] 20. Light-emitting block; 200. Epitaxial layer; 201. Bump;

[0031] 30. Reflective layer; 31. First material layer; 32. Second material layer; 301. Light exit aperture;

[0032] 40. Metal electrode layer; 41. Arc-shaped groove;

[0033] 50. Confocal resonant cavity;

[0034] 60. Transparent electrode layer. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0036] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0037] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of this disclosure. For example... Figure 1 As shown, the light-emitting diode includes: a light-emitting block 20, a reflective layer 30, and a metal electrode layer 40.

[0038] like Figure 1As shown, the light-emitting block 20 is located on the surface of the metal electrode layer 40, the reflective layer 30 is located on the surface of the metal electrode layer 40, and the reflective layer 30 covers the light-emitting block 20. The surface of the reflective layer 30 away from the metal electrode layer 40 is provided with a light-emitting hole 301, and the light-emitting hole 301 exposes the light-emitting block 20.

[0039] The light-emitting diode provided in this embodiment has a light-emitting block 20 disposed on the surface of a metal electrode layer 40, and a reflective layer 30 fully covering the light-emitting block 20 and part of the metal electrode layer 40 to form a reflective cavity surrounding the light-emitting block 20, and a light-emitting hole 301 is precisely opened at the top, exposing only the light-emitting block 20.

[0040] In this structure, the reflective layer 30 and the metal electrode layer 40 together form a reflective cavity. The disordered light emitted from the light-emitting block 20 first scatters in all directions. The light rays heading towards the reflective layer 30 are gradually guided to the top after multiple reflections. A small amount of light rays that propagate directly upwards are emitted directly through the light-emitting aperture 301. The reflective cavity can repeatedly collect and redirect stray light, ultimately allowing light rays aligned with the direction of the light-emitting aperture 301 to be emitted efficiently. This converges the originally divergent light beam into approximately parallel or small-angle light rays, effectively improving the utilization rate of small-angle light required in AR applications, while reducing the probability of the emitted light being absorbed, thereby improving light extraction efficiency.

[0041] Optionally, such as Figure 1 As shown, the surface of the metal electrode layer 40 has an arc groove 41, and the surface of the light-emitting block 20 near the metal electrode layer 40 is in contact with the groove surface of the arc groove 41.

[0042] like Figure 1 As shown, the outer wall surface of the film layer covering the light-emitting block 20 of the reflective layer 30 is an arc-shaped surface, and the arc-shaped surface and the groove surface of the arc groove 41 form a confocal resonant cavity 50.

[0043] In the above implementation, the confocal resonant cavity 50 formed by the arc-shaped surface and the groove surface of the arc-shaped groove 41 causes the light emitted by the light-emitting block 20 to gradually converge towards the confocal point after multiple coordinated reflections within the cavity by the reflective layer 30 and the metal reflective layer 30. Ultimately, the light can only be emitted directionally from the micro-hole, and the divergence angle is strictly constrained to within ±10°, perfectly matching the AR display's requirement for a small-angle light source.

[0044] In related technologies, some light rays are trapped inside the device due to total internal reflection and cannot escape. However, in this embodiment, the multiple reflections of the confocal resonant cavity 50 prolong the photon propagation path, giving light rays that might otherwise be lost due to total internal reflection a greater chance to reach the top micro-aperture.

[0045] In addition to reflecting light, the metal reflective layer 30 also has a certain thermal conductivity. The arc groove 41 structure can increase the contact area between the light-emitting block 20 and the metal reflective layer 30, assist the heat dissipation of the light-emitting block 20, and alleviate the efficiency decay caused by high temperature.

[0046] Meanwhile, the airtight characteristics of the confocal resonant cavity 50 can reduce the erosion of the surface of the light-emitting block 20 by external dust and moisture, and extend the device life; the arc-shaped confocal resonant cavity 50 has better mechanical stability and can reduce the risk of film cracking caused by packaging stress.

[0047] Optionally, the cross-sectional shape of the confocal resonant cavity 50 is circular or elliptical.

[0048] The cross-sectional shape of the confocal resonant cavity 50 refers to the shape of the cross-section of the confocal resonant cavity 50 in the direction perpendicular to the surface of the metal electrode layer 40.

[0049] For example, when the cross-sectional shape of the confocal resonant cavity 50 is circular, the symmetry is maximized and the optical path evolution in all directions is completely consistent.

[0050] This confocal resonant cavity 50 ensures that light emitted from the light-emitting block 20 in any direction, after being reflected by the reflective layer 30 and the metal reflective layer 30 within the circular cavity, converges towards the common focal point along a symmetrical path. Because the reflection trajectories of light rays at each angle are symmetrical, the final angular distribution of the emitted light is highly uniform, and the divergence angle is strictly controlled within ±10°.

[0051] Meanwhile, the circular structure only requires a single radius of curvature to define the cavity shape, without having to consider the difference between the major and minor axes, which reduces the processing complexity of the arc groove 41 and the arc surface of the reflective layer 30, making it more suitable for the consistency requirements in mass production.

[0052] In this embodiment, an arc-shaped groove is designed on the surface of the metal electrode layer to form a concave reflector, which can focus the light so that the path of the light after each reflection is precisely guided toward the light-emitting hole at the top. This can reduce the number of reflections that photons may experience during their lifetime, thereby greatly reducing the time that photons spend in the active region with high loss, reducing the absorption probability, and increasing the light extraction efficiency.

[0053] For example, when the cross-section of the confocal resonant cavity 50 is elliptical, by adjusting the ratio of the major and minor axes of the ellipse (e.g., the major axis corresponds to the horizontal direction and the minor axis corresponds to the vertical direction), the light can be reflected more times in a specific direction (e.g., the direction of the major axis), thereby forming a higher light intensity concentration in that direction.

[0054] Optionally, the orthographic projection of the light-emitting aperture 301 onto the surface of the metal electrode layer 40 is located in the central region of the orthographic projection of the light-emitting block 20 onto the surface of the metal electrode layer 40. That is, the light-emitting aperture 301 is distributed in the central region of the light-emitting block 20.

[0055] This ensures that light is emitted evenly from the center of the light-emitting block 20, resulting in a more uniform intensity distribution of the emitted light. It avoids uneven light intensity caused by the offset of the light emission position, thereby improving the overall uniformity and visual effect of the AR display.

[0056] Secondly, the centrally located light-emitting aperture 301 allows light to propagate along a more symmetrical path, which helps to better utilize the symmetrical characteristics of the confocal resonant cavity 50. This allows the light to converge more regularly towards the light-emitting aperture 301 after multiple reflections within the cavity, further improving the light extraction efficiency and reducing disordered scattering and loss of light within the cavity.

[0057] Optionally, at least one light-emitting hole 301 is provided on the surface of the reflective layer 30. That is, one or more light-emitting holes 301 can be provided on the reflective layer 30.

[0058] When there are multiple light-emitting holes 301, the multiple light-emitting holes 301 are arranged at intervals, and the sum of the cross-sectional areas of the multiple light-emitting holes 301 is the first area.

[0059] When there is only one light-emitting aperture 301, the cross-sectional area of ​​the light-emitting aperture 301 is the second area, and the ratio of the first area to the second area is 0.9 to 1.1.

[0060] In the above implementation, the total area (first area) of the multiple light-emitting apertures 301 is made comparable to the area of ​​a single large light-emitting aperture 301 (second area), resulting in a significantly smaller aperture diameter for each small aperture compared to the large aperture. See also Figure 2 The optical path diagram indicated by the middle arrow effectively suppresses the phenomenon of light escaping at an angle and improves the directionality of the emitted light.

[0061] like Figure 2 As shown, for a large-sized light-emitting aperture 301, some light rays, when propagating within the reflective layer 30, may not be able to strike the aperture perpendicularly due to the incident angle approaching or exceeding the critical angle. Instead, they may pass through the aperture edge along an oblique path, resulting in the divergence of the final emitted light angle. In contrast, the arrangement of multiple small-aperture light-emitting apertures 301 significantly reduces the probability of oblique incident light reaching the aperture edge due to the smaller aperture diameter. This makes it easier for light rays to enter the small aperture through a vertical or near-vertical path and ultimately exit in a direction closer to the axial direction.

[0062] Furthermore, the focusing constraint effect of small apertures is stronger. Multiple small apertures are equivalent to forming multiple directional channels within the reflective cavity, forcing light to converge more concentratedly to the nearest aperture after multiple reflections, rather than diffusing to the wide edges of the large aperture. This maintains a total light output comparable to that of the large aperture while optimizing the light path guidance by reducing the size of each aperture, ultimately effectively reducing oblique light emission, further converging the beam divergence angle, and improving the collimation of light and image clarity in AR displays.

[0063] Optionally, the light-emitting diode further includes a transparent electrode layer 60, which is located on the surface of the reflective layer 30 away from the metal electrode layer 40 and extends into the light-emitting aperture 301 and is connected to the light-emitting block 20.

[0064] Using a transparent electrode layer 60 as the electrode for injecting current into the light-emitting block 20 enables both electrical connection and optical transmission. The transparent electrode layer 60 is located above the reflective layer 30 and extends into the light-emitting hole 301, connecting with the light-emitting block 20. It can effectively transmit current to the light-emitting block 20, ensuring its normal light emission, and due to its transparency, it will not block the light emitted from the light-emitting hole 301, ensuring light emission efficiency and avoiding the problem of traditional opaque electrodes blocking the light path.

[0065] Meanwhile, the transparent electrode layer 60 can serve as a protective layer, reducing the erosion and damage of the contact area between the light-emitting block 20 and the reflective layer 30 by the external environment, enhancing the stability and reliability of the device, and extending its service life.

[0066] Optionally, the transmittance of the transparent electrode layer 60 is greater than or equal to 90%.

[0067] In this embodiment, a material with a light transmittance of over 90% is used as the transparent electrode layer 60. The light transmittance is ≥90%, ensuring the high light transmittance of the transparent electrode layer 60. This allows the light emitted from the light-emitting block 20 to the light-emitting hole 301 to have almost no attenuation, maximizing the retention of light energy and avoiding brightness reduction caused by electrode blockage.

[0068] For example, the transparent electrode layer 60 may be an ITO (indium tin oxide) layer.

[0069] Among its advantages, the ITO layer offers a balanced combination of optical and electrical properties. It boasts a transmittance of 90% to 95% in the visible light band (400-700nm) and low sheet resistance, enabling rapid and uniform current injection and reducing hotspots caused by localized current accumulation in the light-emitting block 20, resulting in more uniform emitted light. Furthermore, ITO exhibits chemical stability, strong high-temperature and moisture resistance, and high reliability.

[0070] For example, the transparent electrode layer 60 may be an IZO (indium zinc oxide) layer.

[0071] Compared to ITO layers, IZO layers offer better flexibility and stronger adhesion between IZO and reflective layer 30. Furthermore, IZO has more abundant and lower-priced zinc reserves, which can reduce production costs.

[0072] For example, the transparent electrode layer 60 may be an AZO (aluminum-doped zinc oxide) layer.

[0073] AZO exhibits excellent high-temperature resistance and superior thermal stability compared to ITO, making it suitable for high-temperature packaging applications. Its light transmittance can reach 90%, and its sheet resistance is close to that of ITO.

[0074] For example, the transparent electrode layer 60 may be a graphene layer.

[0075] Graphene has ultra-high light transmittance and extremely low resistance, as well as excellent mechanical flexibility, making it suitable for foldable AR display needs.

[0076] Optionally, the thickness of the transparent electrode layer 60 is 2,500 angstroms to 3,500 angstroms.

[0077] The transparent electrode layer 60 with the aforementioned thickness range can effectively shield stray light that may be generated by the reflective layer 30 and the metal electrode layer 40 while ensuring high light transmittance, reducing interference with the emitted light spectrum and making the AR display colors purer.

[0078] Meanwhile, the transparent electrode layer 60 of this thickness maintains low resistance, ensuring uniform current injection into the light-emitting block 20. This avoids excessive resistance and poor current transmission due to excessive thickness, or unnecessary material waste and increased costs due to excessive thickness. Moreover, the transparent electrode layer 60 of this thickness range is mechanically stable and not easily broken or peeled off by external forces. It can adhere well to the surface of the reflective layer 30 and extend to the light-emitting hole 301 to connect with the light-emitting block 20, ensuring a stable electrical connection between the transparent electrode layer 60 and the light-emitting block 20, thereby improving the reliability and lifespan of the entire light-emitting diode structure.

[0079] For example, the thickness of the transparent electrode layer 60 is 3000 angstroms.

[0080] Optionally, such as Figure 1 As shown, the reflective layer 30 includes multiple alternating layers of first material layer 31 and multiple layers of second material layer 32, wherein the refractive indices of the first material layer 31 and the second material layer 32 are different.

[0081] In this embodiment of the disclosure, the reflective layer 30 is constructed by alternating layers of a first material layer 31 and a second material layer 32 to form a distributed Bragg reflector (DBR).

[0082] For example, one of the first material layer 31 and the second material layer 32 is a TiO2 layer, and the other of the first material layer 31 and the second material layer 32 is a SiO2 layer.

[0083] In this process, DBR uses two materials with significantly different refractive indices stacked periodically to form a strong reflection band by utilizing the principle of light interference. When light shines from the light-emitting block 20 to the reflective layer 30, light of a specific wavelength is coherently enhanced after multiple reflections at the interlayer interface, achieving a reflectivity of over 95%. This significantly reduces the disordered leakage of light energy to the outside of the cavity and improves light extraction efficiency.

[0084] Furthermore, the DBR's reflection band is wavelength selective, which can accurately reflect the main emission band of the light-emitting block 20 while transmitting other stray wavelengths. This not only enhances the directional output of effective light but also suppresses interference from non-target wavelengths, thus optimizing the spectral purity of the emitted light.

[0085] Optionally, the number of layers of both the first material layer 31 and the second material layer 32 can be 1 to 20.

[0086] For example, when the number of layers of the first material layer 31 is 1 to 5, the DBR layer is suitable for scenarios with low reflectivity requirements, where the reflectivity is about 90%.

[0087] For example, when the number of layers of the first material layer 31 is 10 to 20, the reflectivity of the DBR layer can reach more than 95%, which is suitable for high-efficiency LEDs.

[0088] Optionally, the thickness of the first material layer 31 is 100 nm to 110 nm. The thickness of the second material layer 32 is 60 nm to 64 nm.

[0089] For red LEDs, the first material layer 31 is a silicon dioxide layer with a thickness of 100 nm, and the second material layer 32 is a titanium dioxide layer with a thickness of 60 nm. When the material layer thickness of the DBR is within the above range, it exhibits high reflectivity for red light.

[0090] Optionally, the light-emitting block 20 includes a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer stacked sequentially.

[0091] In this embodiment of the disclosure, one of the first semiconductor layer and the second semiconductor layer is a p-type layer, and the other of the first semiconductor layer and the second semiconductor layer is an n-type layer.

[0092] As an example, the first semiconductor layer is a p-type layer and the second semiconductor layer is an n-type layer.

[0093] Optionally, the first semiconductor layer is an indium-doped p-type AlInP layer. The thickness of the p-type AlInP layer can be from 0.5 μm to 3 μm.

[0094] Optionally, the multiple quantum well layer includes alternating AlGaInP quantum well layers and AlGaInP quantum barrier layers. The Al content in the AlGaInP quantum well layers and AlGaInP quantum barrier layers is different. The multiple quantum well layer may include 3 to 8 alternating stacked AlGaInP quantum well layers and AlGaInP quantum barrier layers.

[0095] As an example, in an embodiment of this disclosure, the multi-quantum-well layer includes five alternating stacked AlGaInP quantum-well layers and AlGaInP quantum-barrier layers.

[0096] Optionally, the thickness of the multi-quantum well layer can be from 150 nm to 200 nm.

[0097] Optionally, the second semiconductor layer is an n-type AlGaInP layer. The thickness of the n-type AlGaInP layer can be from 0.5 μm to 3 μm.

[0098] Optionally, such as Figure 1 As shown, the light-emitting diode also includes a substrate 10, and a metal electrode layer 40 is located on the substrate 10.

[0099] For example, substrate 10 is a sapphire substrate. Sapphire substrates have high light transmittance, meaning substrate 10 is a transparent substrate. Furthermore, sapphire material is relatively hard and chemically stable, giving the light-emitting diode good luminous effect and stability.

[0100] Optionally, the metal electrode layer 40 may include at least one of the following: AuBe layer, Au layer, Ti layer, Ni layer, and Pt layer.

[0101] For example, the metal electrode layer 40 includes an Au layer, an AuGe layer, and a Pt layer sequentially stacked on the surface of the epitaxial layer 200.

[0102] The last metal layer of the metal electrode layer 40 is set as a Pt layer, which covers the AuGe layer. This effectively prevents Ge elements from diffusing upwards during annealing, thus ensuring the total amount of elements diffusing into the semiconductor and allowing the metal electrode layer 40 to achieve a better ohmic contact effect.

[0103] Optionally, the thickness of the Au layer is 80 to 150 angstroms. The Au layer has good conductivity, which can improve the ohmic contact effect between the metal electrode layer 40 and the light-emitting block 20.

[0104] For example, the thickness of the Au layer is 100 angstroms.

[0105] Optionally, the thickness of the AuGe layer is between 800 and 1500 angstroms. The AuGe layer also has good conductivity, which can reduce the amount of Au metal used, thereby reducing the fabrication cost of the electrode.

[0106] For example, the thickness of the AuGe layer is 1000 angstroms.

[0107] Optionally, the thickness of the Pt layer is 450 to 600 angstroms. Setting the last metal layer of the electrode as a Pt layer, allowing the Pt layer to cover the AuGe layer, can ensure the AuGe layer.

[0108] For example, the thickness of the Pt layer is 500 angstroms.

[0109] Figure 3This is a flowchart illustrating a method for fabricating a light-emitting diode according to an embodiment of this disclosure. Figure 3 As shown, the preparation method includes:

[0110] S11: An epitaxial layer 200 is formed on a temporary substrate 11.

[0111] For example, the epitaxial layer 200 may include a first semiconductor layer, a multiple quantum well layer and a second semiconductor layer sequentially stacked on the temporary substrate 11.

[0112] The first semiconductor layer has a first conductivity type, the second semiconductor layer has a second conductivity type different from the first conductivity type, and the multiple quantum well layer is used to generate light through electron-hole recombination.

[0113] In this process, one of the first semiconductor layer and the second semiconductor layer is a p-type layer, and the other of the first semiconductor layer and the second semiconductor layer is an n-type layer.

[0114] As an example, the first semiconductor layer is a p-type layer and the second semiconductor layer is an n-type layer.

[0115] For example, the first semiconductor layer is an indium-doped p-type AlInP layer. The thickness of the p-type AlInP layer can be from 0.5 μm to 3 μm.

[0116] For example, the second semiconductor layer may be an n-type AlGaInP layer. The thickness of the n-type AlGaInP layer may be from 0.5 μm to 3 μm.

[0117] Optionally, the multiple quantum well layer includes alternating AlGaInP quantum well layers and AlGaInP quantum barrier layers. The Al content in the AlGaInP quantum well layers and AlGaInP quantum barrier layers is different. The multiple quantum well layer may include 3 to 8 alternating stacked AlGaInP quantum well layers and AlGaInP quantum barrier layers.

[0118] As an example, in an embodiment of this disclosure, the multi-quantum-well layer includes five alternating stacked AlGaInP quantum-well layers and AlGaInP quantum-barrier layers.

[0119] Optionally, the thickness of the multi-quantum well layer can be from 150 nm to 200 nm.

[0120] In step S11, after forming the epitaxial layer 200 on the temporary substrate 11, the epitaxial layer 200 can be etched to form a plurality of bumps 201 on the epitaxial layer 200.

[0121] like Figure 4 As shown, the surface of the epitaxial layer 200 has bumps 201, and the surface of the bumps 201 away from the temporary substrate 11 is an arc surface.

[0122] S12: A metal electrode layer 40 is formed on the surface of the epitaxial layer 200, so that the metal electrode layer 40 covers the bump 201.

[0123] like Figure 4 As shown, the metal electrode layer 40 covers the epitaxial layer 200, and an arcuate groove 41 is formed in the area where the metal electrode layer 40 contacts the bump 201.

[0124] For example, the metal electrode layer 40 includes an Au layer, an AuGe layer, and a Pt layer sequentially stacked on the surface of the epitaxial layer 200.

[0125] For example, the thickness of the AuBe layer is between 800 angstroms and 1200 angstroms. As an example, the thickness of the AuBe layer is 1000 angstroms.

[0126] For example, the thickness of the Au layer is between 800 angstroms and 1200 angstroms. As an example, the thickness of the Au layer is 900 angstroms.

[0127] For example, the thickness of the Ti layer is 300 to 700 angstroms. As an example, the thickness of the Ti layer is 500 angstroms.

[0128] For example, the thickness of the Ni layer is between 2000 angstroms and 4000 angstroms. As an example, the thickness of the Ni layer is 3000 angstroms.

[0129] S13: Bond the surface of the metal electrode layer 40 away from the epitaxial layer 200 to the substrate 10, and remove the temporary substrate 11.

[0130] like Figure 5 As shown, the surface of the metal electrode layer 40 away from the epitaxial layer 200 is firmly bonded to the substrate 10 by means of eutectic bonding, adhesive bonding or other methods, and then the temporary substrate 11 is removed by laser lift-off or other techniques.

[0131] S14: Etch epitaxial layer 200 to form light-emitting block 20.

[0132] like Figure 6 As shown, after etching the epitaxial layer 200, the area where the bump 201 is located is retained to form a light-emitting block 20 including the bump 201.

[0133] For example, such as Figure 6 As shown, the portion of the light-emitting block 20 located on the metal electrode layer 40 is trapezoidal in shape.

[0134] like Figure 6 As shown, before step S15, the method further includes etching the metal electrode layer 40 to form an isolation trench exposing the substrate 10, thereby obtaining a plurality of pixel units arranged at intervals.

[0135] S15: A reflective layer 30 is formed on the surface of the metal electrode layer 40, so that the reflective layer 30 covers the light-emitting block 20.

[0136] like Figure 7 As shown, the outer wall surface of the film layer covering the light-emitting block 20 of the reflective layer 30 is an arc-shaped surface, and the arc-shaped surface and the groove surface of the arc groove 41 form a confocal resonant cavity 50.

[0137] For example, the cross-sectional shape of the confocal resonant cavity 50 is circular or elliptical.

[0138] like Figure 7 As shown, the reflective layer 30 includes multiple alternating layers of first material layer 31 and multiple layers of second material layer 32, wherein the refractive indices of the first material layer 31 and the second material layer 32 are different.

[0139] For example, one of the first material layer 31 and the second material layer 32 is a TiO2 layer, and the other of the first material layer 31 and the second material layer 32 is a SiO2 layer.

[0140] S16: A light-emitting aperture 301 is formed on the reflective layer 30.

[0141] like Figure 8 As shown, the light-emitting hole 301 exposes the light-emitting block 20.

[0142] Step S16 may specifically include: precisely forming a light hole 301 on the reflective layer 30 through photolithography, etching and other processing techniques.

[0143] S17: A transparent electrode layer 60 is formed on the surface of the reflective layer 30 that is away from the metal electrode layer 40.

[0144] like Figure 8 As shown, the transparent electrode layer 60 extends into the light-emitting hole 301 and is connected to the light-emitting block 20.

[0145] Specifically, this may include depositing a transparent electrode layer 60 on the surface of the reflective layer 30 away from the metal electrode layer 40 by magnetron sputtering or electron beam evaporation, and extending it into the light-emitting hole 301 to make direct ohmic contact with the light-emitting block 20, thereby achieving the dual functions of electrical conduction and optical light transmission.

[0146] For example, the transparent electrode layer 60 may be an ITO layer or an IZO layer.

[0147] Finally, the substrate 10 can be invisibly cut and scratched, which can effectively reduce the loss of brightness. Then, the light-emitting diode is tested.

[0148] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. The data therein represents only illustrative examples. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A light-emitting diode, characterized in that, The light-emitting diode includes: a light-emitting block (20), a reflective layer (30), and a metal electrode layer (40); The light-emitting block (20) is located on the surface of the metal electrode layer (40), and the reflective layer (30) is located on the surface of the metal electrode layer (40) and covers the light-emitting block (20). The surface of the reflective layer (30) away from the metal electrode layer (40) is provided with a light-emitting hole (301), and the light-emitting hole (301) exposes the light-emitting block (20).

2. The light-emitting diode according to claim 1, characterized in that, The surface of the metal electrode layer (40) has an arc groove (41), and the surface of the light-emitting block (20) near the metal electrode layer (40) is in contact with the groove surface of the arc groove (41); The outer wall surface of the reflective layer (30) covering the light-emitting block (20) is an arc-shaped surface, and the arc-shaped surface and the groove surface of the arc groove (41) form a confocal resonant cavity (50).

3. The light-emitting diode according to claim 2, characterized in that, The cross-sectional shape of the confocal resonant cavity (50) is circular or elliptical.

4. The light-emitting diode according to claim 1, characterized in that, The orthographic projection of the light-emitting aperture (301) on the surface of the metal electrode layer (40) is located in the central region of the orthographic projection of the light-emitting block (20) on the surface of the metal electrode layer (40).

5. The light-emitting diode according to claim 4, characterized in that, At least one light-emitting hole (301) is provided on the surface of the reflective layer (30). When there are multiple light-emitting holes (301), the multiple light-emitting holes (301) are arranged at intervals, and the sum of the cross-sectional areas of the multiple light-emitting holes (301) is the first area. When there is one light-emitting aperture (301), the cross-sectional area of ​​the light-emitting aperture (301) is the second area, and the ratio of the first area to the second area is 0.9 to 1.

1.

6. The light-emitting diode according to any one of claims 1 to 5, characterized in that, The light-emitting diode further includes a transparent electrode layer (60), which is located on the surface of the reflective layer (30) away from the metal electrode layer (40) and extends into the light-emitting hole (301) and is connected to the light-emitting block (20).

7. The light-emitting diode according to claim 6, characterized in that, The thickness of the transparent electrode layer (60) is 2,500 angstroms to 3,500 angstroms.

8. The light-emitting diode according to claim 6, characterized in that, The light transmittance of the transparent electrode layer (60) is greater than or equal to 90%.

9. The light-emitting diode according to any one of claims 1 to 5, characterized in that, The reflective layer (30) includes multiple alternating layers of first material layers (31) and multiple layers of second material layers (32), wherein the first material layers (31) and the second material layers (32) have different refractive indices.

10. A method for fabricating a light-emitting diode, characterized in that, The preparation method includes: An epitaxial layer (200) is formed on a temporary substrate (11), the surface of the epitaxial layer (200) having bumps (201), the surface of the bumps (201) away from the temporary substrate (11) being an arc surface; A metal electrode layer (40) is formed on the surface of the epitaxial layer (200) such that the metal electrode layer (40) covers the bump (201). The surface of the metal electrode layer (40) away from the epitaxial layer (200) is bonded to the substrate (10), and the temporary substrate (11) is removed. The epitaxial layer (200) is etched to form a light-emitting block (20), the light-emitting block (20) including the bump (201); A reflective layer (30) is formed on the surface of the metal electrode layer (40) so that the reflective layer (30) covers the light-emitting block (20). A light-emitting hole (301) is formed on the reflective layer (30), and the light-emitting hole (301) exposes the light-emitting block (20). A transparent electrode layer (60) is formed on the surface of the reflective layer (30) away from the metal electrode layer (40), and the transparent electrode layer (60) extends into the light-emitting hole (301) and is connected to the light-emitting block (20).

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