Green light micro-led epitaxial wafer, preparation method thereof and micro-led

Abstract

The application discloses a green light Micro-LED epitaxial wafer and a preparation method thereof and a Micro-LED, and relates to the field of semiconductor photoelectric devices. The green light Micro-LED epitaxial wafer comprises, in sequence, a substrate, a buffer layer, a first stress balancing layer, a non-doped GaN layer, a second stress balancing layer, an N-type GaN layer, an electron regulating layer, a multi-quantum well layer and a P-type GaN layer; wherein the first stress balancing layer is a Ga-polar AlGaN layer; the second stress balancing layer comprises alternately-stacked N-polar GaN layers and N-polar AlGaN layers; and the electron regulating layer comprises alternately-stacked Ga-polar N-type AlInGaN layers and Ga-polar N-type GaN layers. By implementing the application, the light emitting efficiency and the light emitting uniformity of the green light Micro-LED can be improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic devices, and more particularly to a green Micro-LED epitaxial wafer and its preparation method, and Micro-LED. Background Technology

[0002] Type V-III third-generation semiconductor materials are now widely used in lighting, optical communication, photoelectric detection, and power devices. GaN, a typical representative of third-generation semiconductor materials, has great potential in Micro-LED (micro-LED) applications due to its excellent optoelectronic properties. However, Micro-LEDs have extremely high requirements for wavelength uniformity. Traditional Micro-LED epitaxial wafers suffer from high lattice mismatch, resulting in significant stress in the active layer, leading to low luminous efficiency and poor wavelength uniformity. This phenomenon is particularly pronounced in green Micro-LEDs with a high In content. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a green Micro-LED epitaxial wafer with high luminous efficiency and high wavelength uniformity.

[0004] The technical problem that this invention also needs to solve is to provide a green Micro-LED with high luminous efficiency and high wavelength uniformity.

[0005] To address the aforementioned issues, this invention discloses a green Micro-LED epitaxial wafer, comprising a substrate, and a buffer layer, a first stress balancing layer, an undoped GaN layer, a second stress balancing layer, an N-type GaN layer, an electronic control layer, a multiple quantum well layer, and a P-type GaN layer sequentially stacked on the substrate.

[0006] The first stress balancing layer is a Ga polar AlGaN layer; the second stress balancing layer includes alternating layers of N polar GaN layers and N polar AlGaN layers; the electronic control layer includes alternating layers of Ga polar N-type AlInGaN layers and Ga polar N-type GaN layers.

[0007] As an improvement to the above technical solution, the N-polar GaN layer is doped with Si, and the doping concentration is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 ;

[0008] The N-polar AlGaN layer is doped with Si at a concentration of 1 × 10⁻⁶. 17 cm -3 ~1×10 19 cm-3 .

[0009] As an improvement to the above technical solution, along the growth direction of the green Micro-LED epitaxial wafer, the Al composition in the Ga polar AlGaN layer exhibits an increasing variation; and / or

[0010] Along the growth direction of the green Micro-LED epitaxial wafer, the Al composition in the Ga polar N-type AlInGaN layer shows an increasing change.

[0011] As an improvement to the above technical solution, the thickness of the first stress balancing layer is 10nm~100nm, and the proportion of its Al component is 0.01~0.2%; and / or

[0012] The second stress balancing layer has 1 to 20 cycles; and / or

[0013] The thickness of the second stress balancing layer is 10 nm to 100 nm, and the ratio of the thickness of the N-polar GaN layer to the thickness of the N-polar AlGaN layer is 1:1 to 10:1; and / or

[0014] The proportion of Al component in the N-polar AlGaN layer is 0.01~0.15; and / or

[0015] The period number of the electronic control layer is 1 to 20; and / or

[0016] The thickness of the Ga polar N-type AlInGaN layer is 1 nm to 10 nm, with an Al content of 0.01% to 0.1% and an In content of 0.01% to 0.1%; the doping concentration is 1 × 10⁻⁶. 17 cm -3 ~1×10 18 cm -3 ; and / or

[0017] The thickness of the Ga polar N-type GaN layer is 5nm~15nm, and the doping concentration is 1×10⁻⁶. 17 cm -3 ~1×10 18 cm -3 .

[0018] Accordingly, the present invention also discloses a method for preparing a green Micro-LED epitaxial wafer, comprising:

[0019] Provide substrate;

[0020] A buffer layer is grown on the substrate;

[0021] A first stress-balancing layer is grown on the buffer layer;

[0022] An undoped GaN layer is grown on the first stress equilibrium layer;

[0023] A second stress-balancing layer is grown on an undoped GaN layer;

[0024] An N-type GaN layer is grown on the second stress equilibrium layer;

[0025] An electronic control layer is grown on an N-type GaN layer;

[0026] Growing a multi-quantum-well layer on an electronic control layer;

[0027] Growing P-type GaN layers on multi-quantum-well layers;

[0028] The first stress balancing layer is a Ga polar AlGaN layer; the second stress balancing layer includes alternating layers of N polar GaN layers and N polar AlGaN layers; the electronic control layer includes alternating layers of Ga polar N-type AlInGaN layers and Ga polar N-type GaN layers.

[0029] As an improvement to the above technical solution, the growth temperature of the first stress balance layer is 1000℃~1100℃, and the growth atmosphere is a mixed gas atmosphere of H2 and NH3, with a volume ratio of H2 to NH3 of 1:1~1:2.

[0030] As an improvement to the above technical solution, the step of growing a buffer layer on the substrate includes:

[0031] An AlN layer was grown using PVD as a buffer layer.

[0032] The substrate with the AlN layer was heat-treated at 1000℃~1100℃ in a mixed gas atmosphere of H2, N2 and NH3; wherein the volume ratio of H2, N2 and NH3 was 1:0.5:1~1:1:2.

[0033] The thickness of the buffer layer is ≤20nm.

[0034] As an improvement to the above technical solution, the growth temperature of the second stress balance layer is 50°C to 200°C lower than the growth temperature of the undoped GaN layer.

[0035] The growth atmosphere of the second stress balance layer is a mixed gas atmosphere of N2 and NH3, with a volume ratio of N2 to NH3 of 1:1 to 1:10.

[0036] As an improvement to the above technical solution, the growth temperature of the electronic control layer is 950℃~1080℃, and its growth atmosphere is a mixture of H2 and NH3, with a volume ratio of H2 to NH3 of 1:1~1:10.

[0037] Accordingly, the present invention also discloses a green Micro-LED, which includes the above-mentioned green Micro-LED epitaxial wafer.

[0038] Implementing this invention has the following beneficial effects:

[0039] An embodiment of the present invention provides a green Micro-LED epitaxial wafer comprising a substrate, a buffer layer, a first stress balancing layer, an undoped GaN layer, a second stress balancing layer, an N-type GaN layer, an electron control layer, a multiple quantum well layer, and a P-type GaN layer. The first stress balancing layer is a Ga-polar AlGaN layer; the second stress balancing layer comprises alternating layers of N-polar GaN and N-polar AlGaN layers; and the electron control layer comprises alternating layers of Ga-polar N-type AlInGaN and Ga-polar N-type GaN layers. Based on the structure of this embodiment, firstly, the first stress balancing layer (Ga-polar AlGaN layer) can reduce the ingress of oxygen impurities, lower tensile stress, and improve the crystal quality of the epitaxial wafer. Secondly, due to coherent growth induction, the second stress balancing layer generates compressive stress, thereby effectively balancing tensile stress and reducing stress-induced dislocations. Thirdly, the second stress balancing layer is nitrogen-polar (N-polar), which enhances electron confinement capabilities, restricting electron migration from the bottom and reducing the probability of electrostatic breakdown. Fourth, the introduction of a Ga polar N-type AlInGaN layer into the electron control layer can raise the energy band, enabling electrons to enter the multi-quantum well layer more uniformly and improving luminescence uniformity. Fifth, the periodic stacking of Ga polar N-type AlInGaN layers with Ga polar N-type GaN layers can effectively buffer mismatch stress, promote a more uniform distribution of In composition in the quantum well layer, improve crystal quality, and enhance luminescence efficiency and uniformity. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of a green Micro-LED epitaxial wafer in one embodiment of the present invention;

[0041] Figure 2 This is a flowchart of a method for preparing a green Micro-LED epitaxial wafer according to an embodiment of the present invention;

[0042] In this structure, 100 is the substrate, 200 is the buffer layer, 300 is the first stress balancing layer, 400 is the undoped GaN layer, 500 is the second stress balancing layer, 510 is the N-polar GaN layer, 520 is the N-polar AlGaN layer, 600 is the N-type GaN layer, 700 is the electronic control layer, 710 is the Ga-polar N-type AlInGaN layer, 720 is the Ga-polar N-type GaN layer, 800 is the multi-quantum well layer, and 900 is the P-type GaN layer. Detailed Implementation

[0043] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional range of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0045] See Figure 1 As a first aspect of the present invention, the present invention discloses a green Micro-LED epitaxial wafer, which includes a substrate 100, a buffer layer 200, a first stress balancing layer 300, an undoped GaN layer 400, a second stress balancing layer 500, an N-type GaN layer 600, an electronic control layer 700, a multi-quantum well layer 800 and a P-type GaN layer 900 sequentially stacked on the substrate 100.

[0046] The first stress balancing layer 300 is a Ga-polar AlGaN layer; the second stress balancing layer 500 includes alternating layers of N-polar GaN layers 510 and N-polar AlGaN layers 520; and the electron control layer 700 includes alternating layers of Ga-polar N-type AlInGaN layers 710 and Ga-polar N-type GaN layers 720. The first stress balancing layer 300 (Ga-polar AlGaN layer) reduces the ingress of oxygen impurities, lowers tensile stress, and improves the crystal quality of the epitaxial wafer. The second stress balancing layer 500, with its alternating layers of N-polar GaN layers 510 and N-polar AlGaN layers 520, generates compressive stress due to coherent growth, effectively balancing tensile stress and reducing stress-induced dislocations. Simultaneously, the second stress balancing layer 500 is nitrogen-polar (N-polar), which enhances electron confinement, restricting electron migration from the bottom and reducing the probability of electrostatic breakdown. In the electron control layer 700, the energy band can be raised by introducing a Ga polar N-type AlInGaN layer 710, which promotes the more uniform entry of electrons into the multi-quantum well layer 800 and improves the uniformity of light emission. Moreover, the growth structure of the periodic stacking of the Ga polar N-type AlInGaN layer 710 and the Ga polar N-type GaN layer 720 can effectively buffer the mismatch stress, promote a more uniform distribution of In composition in the quantum well layer, improve crystal quality, and enhance luminous efficiency and luminous uniformity.

[0047] Specifically, the thickness of the first stress balancing layer 300 is 10nm to 100nm. If its thickness is too small, the stress adjustment effect will be insignificant, which may easily lead to epitaxial layer cracks. For example, the thickness of the first stress balancing layer 300 is 15nm, 30nm, 45nm, 60nm, 75nm, or 90nm, but is not limited to these. Preferably, it is 20nm to 50nm.

[0048] Specifically, the proportion of Al component in the first stress balancing layer 300 is 0.01~0.2%, exemplarily 0.03, 0.07, 0.11, 0.15 or 0.19, but not limited thereto. Preferably it is 0.1~0.2%.

[0049] Specifically, the number of cycles of the second stress balancing layer 500 is 1 to 20, exemplarily 2, 4, 6, 8, 10, 12, 14, 16 or 18, but not limited thereto. Preferably, it is 3 to 15.

[0050] Specifically, the thickness of the second stress balancing layer 500 is 10nm to 100nm, exemplarily 15nm, 30nm, 45nm, 60nm, 75nm, or 90nm, but not limited thereto. Preferably, it is 50nm to 100nm.

[0051] Specifically, in the second stress balancing layer 500, the ratio of the thickness of the N-polar GaN layer 510 to the thickness of the N-polar AlGaN layer 520 is (1~10):1, exemplarily 2:1, 4:1, 6:1 or 8:1, but not limited thereto.

[0052] Specifically, the proportion of Al component in the N-polar AlGaN layer 520 is 0.01~0.15. If the proportion of Al component is small, the introduced compressive stress is small, making it difficult to achieve the technical effect of stress balance; if the proportion of Al component is large, it will lead to an increase in the material defect density, affecting the crystal quality of the epitaxial layer. For example, the proportion of Al component in the N-polar AlGaN layer 520 is 0.05, 0.08, 0.11 or 0.14, but is not limited to these. Preferably, it is 0.05~0.12.

[0053] Specifically, the number of cycles in the electronic control layer 700 is 1 to 20, exemplarily 2, 4, 6, 8, 10, 12, 14, 16, or 18, but not limited thereto. Preferably, it is 5 to 15.

[0054] Specifically, the thickness of the Ga polar N-type AlInGaN layer 710 is 1 nm to 10 nm, exemplarily 3 nm, 5 nm, 7 nm or 9 nm, but not limited thereto. Preferably, it is 1 nm to 5 nm.

[0055] Specifically, the Al content in the Ga polar N-type AlInGaN layer 710 is 0.01~0.1, exemplarily 0.02, 0.04, 0.06, 0.08, but not limited thereto. Preferably it is 0.05~0.1.

[0056] Specifically, the proportion of In component in the Ga polar N-type AlInGaN layer 710 is 0.01~0.1, exemplarily 0.02, 0.04, 0.06, 0.08, but not limited thereto. Preferably it is 0.01~0.05.

[0057] Specifically, the doping element of the Ga polar N-type AlInGaN layer 710 is Si or Ge, but not limited to these. Preferably, it is Si, with a doping concentration of 1 × 10⁻⁶. 17 cm -3 ~1×10 18 cm -3 For example, 1.5 × 10 17 cm -3 3×10 17 cm -3 5×10 17 cm -3 7.5×10 17 cm -3 Or 9×10 17 cm-3 However, it is not limited to this. Preferably, it is 1×10⁻⁶. 17 cm -3 ~5×10 17 cm -3 .

[0058] Specifically, the thickness of the Ga polar N-type GaN layer 720 is 5nm to 15nm, exemplarily 6nm, 8nm, 10nm, 12nm or 14nm, but not limited thereto. Preferably, it is 8nm to 15nm.

[0059] Specifically, the doping element of the Ga polar N-type GaN layer 720 is Si or Ge, but not limited to these. Preferably, it is Si, with a doping concentration of 1 × 10⁻⁶. 17 cm -3 ~1×10 18 cm -3 For example, 1.5 × 10 17 cm -3 3×10 17 cm -3 5×10 17 cm -3 7.5×10 17 cm -3 Or 9×10 17 cm -3 However, it is not limited to this. Preferably, it is 1×10⁻⁶. 17 cm -3 ~5×10 17 cm -3 .

[0060] Specifically, in some embodiments, the substrate 100 is a sapphire substrate, a silicon substrate, or a silicon carbide substrate, but is not limited thereto. Preferably, it is a sapphire substrate.

[0061] Specifically, in some embodiments, the buffer layer 200 is an AlN layer or an AlGaN layer, but is not limited to these; preferably, it is an AlN layer. The thickness of the buffer layer 200 is 10 nm to 80 nm. Preferably, in some embodiments, by introducing a first stress balancing layer 300 and a heat treatment process after forming the AlN layer, the thickness of the buffer layer 200 can be reduced to less than 20 nm, further reducing accumulated tensile stress, improving crystal quality, and enhancing luminous efficiency and luminous uniformity.

[0062] Specifically, in some implementations, the thickness of the undoped GaN layer 400 is 1 μm to 3 μm.

[0063] Specifically, in some implementations, the N-type doping (Si) concentration in the N-type GaN layer 600 is 5 × 10⁻⁶. 18 cm-3 ~5×10 19 cm -3 The thickness is 1μm~5μm.

[0064] Specifically, in some embodiments, the multiple quantum well layer 800 includes alternating layers of InGaN well layers and GaN barrier layers, with a period number of 3 to 15. The InGaN quantum well layer has an In content of 0.22 to 0.3% and a thickness of 2 nm to 5 nm, while the GaN barrier layer has a thickness of 5 nm to 15 nm.

[0065] Specifically, in some implementations, the Mg doping concentration in the p-type GaN layer 900 is 1×10⁻⁶. 19 cm -3 ~1×10 21 cm -3 Its thickness is 50nm~200nm.

[0066] It should be noted that the green Micro-LED epitaxial wafer in this invention may also include P-type contact layers commonly used in the art, but is not limited thereto.

[0067] Preferably, in some embodiments, the Al composition in the Ga polar AlGaN layer increases along the growth direction of the green Micro-LED epitaxial wafer. Based on this growth method, the stress accumulation caused by lattice mismatch can be further alleviated, thereby improving the crystal quality and interface stability of the epitaxial structure.

[0068] Preferably, in some embodiments, the Al composition in the Ga polar N-type AlInGaN layer 710 increases gradually along the growth direction of the green Micro-LED epitaxial wafer. This gradient composition design facilitates the generation of bulk polarization charge, forming a three-dimensional electron gas layer, thereby effectively controlling the migration rate of electron carriers, reducing electron overflow, and further improving luminous efficiency.

[0069] Preferably, in some embodiments, the N-polar GaN layer 510 is doped with Si at a doping concentration of 1 × 10⁻⁶. 17 cm -3 ~1×10 19 cm -3 The N-polar AlGaN layer 520 is doped with Si, and the doping concentration is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 Based on this doping, the confinement effect on electrons from the underlying layer can be further optimized.

[0070] See Figure 2As a second aspect of the present invention, the present invention also provides a method for preparing a green Micro-LED epitaxial wafer, which specifically includes the following steps:

[0071] S10: Provides a substrate;

[0072] S11: Buffer layers are grown sequentially on the substrate;

[0073] The buffer layer can be grown using PVD, MOCVD, MBE, or VPE, but is not limited to these methods.

[0074] Preferably, in some embodiments, an AlN layer is grown by PVD as a buffer layer.

[0075] More preferably, in some embodiments, S11 includes:

[0076] S111: An AlN layer is grown using PVD as a buffer layer;

[0077] S112: The substrate with the AlN layer is heat-treated in a mixed gas atmosphere of H2, N2 and NH3 at 1000℃~1100℃;

[0078] The heat treatment time ranges from 10 to 120 seconds. The volume ratio of H2, N2, and NH3 in the mixed gas is 1:0.5:1 to 1:1:2. Heat treatment reduces inhomogeneous lattice regions, which helps lower the dislocation density of subsequent epitaxial layers and improves crystal quality. Based on this heat treatment process and a specific first stress balancing layer, the thickness of the buffer layer can be reduced to below 20 nm, further reducing stress accumulation.

[0079] S12: Grow the first stress balancing layer on the buffer layer;

[0080] Among them, Ga polar AlGaN layers can be grown on the buffer layer by MBE or MOCVD as the first stress balancing layer, but it is not limited to this.

[0081] Preferably, in some embodiments, a Ga polar AlGaN layer is grown by MOCVD as a first stress balancing layer. Specifically, the growth temperature is 1000℃~1100℃, and the growth atmosphere is a mixed gas atmosphere of H2 and NH3, with a volume ratio of H2 to NH3 of 1:(1~2).

[0082] S13: Grow an undoped GaN layer on the first stress balance layer;

[0083] Undoped GaN layers can be grown using PVD, MOCVD, MBE, or VPE, but are not limited to these methods.

[0084] Preferably, in some embodiments, an undoped GaN layer is grown by MOCVD. The growth temperature is 1100℃~1150℃.

[0085] S14: Grow a second stress balancing layer on the undoped GaN layer;

[0086] One method is to alternately grow N-polar GaN layers and N-polar AlGaN layers using MOCVD until a second stress-balanced layer is obtained, but this method is not limited to this.

[0087] Preferably, in some embodiments, a second stress-balanced layer is obtained by alternating growth of N-polar GaN layers and N-polar AlGaN layers via MOCVD. The growth temperature of the second stress-balanced layer is 50°C to 200°C lower than that of the undoped GaN layer to reduce thermal mismatch stress. The growth atmosphere of the second stress-balanced layer is a mixed gas atmosphere of N2 and NH3, with a volume ratio of N2 to NH3 of 1:(1~10).

[0088] S15: An N-type GaN layer is grown on the second stress equilibrium layer;

[0089] N-type GaN layers can be grown via MOCVD, MBE, or VPE, but are not limited to these methods.

[0090] Preferably, in some embodiments, an N-type GaN layer is grown by MOCVD at a growth temperature of 1100°C to 1150°C.

[0091] S16: An electronic control layer is grown on an N-type GaN layer;

[0092] Among them, Ga polar N-type AlInGaN layers and Ga polar N-type GaN layers can be grown alternately by MOCVD until an electronic control layer is obtained, but it is not limited to this.

[0093] Preferably, in some embodiments, an electron control layer is obtained by alternating growth of Ga polar N-type AlInGaN layers and Ga polar N-type GaN layers using MOCVD. The growth temperature of the electron control layer is 950℃~1080℃, and the growth atmosphere is a mixture of H2 and NH3, with a volume ratio of H2 to NH3 of 1:(1~10).

[0094] S17: Growth of multiple quantum well layers on the electronic control layer;

[0095] Specifically, in some implementations, InGaN well layers and GaN barrier layers are alternately grown by MOCVD until a multi-quantum well layer is obtained. The growth temperature of the InGaN well layer is 720℃~760℃, and the growth temperature of the GaN barrier layer is 850℃~950℃.

[0096] S18: Grow a P-type GaN layer on a multi-quantum-well layer;

[0097] P-type GaN layers can be grown via MOCVD, MBE, or VPE, but are not limited to these methods.

[0098] Preferably, in some embodiments, a P-type GaN layer is grown by MOCVD at a growth temperature of 900°C to 1050°C.

[0099] As a third aspect of the present invention, the present invention discloses a Micro-LED comprising the aforementioned Micro-LED epitaxial wafer.

[0100] The present invention will be further described below with reference to specific embodiments:

[0101] Example 1

[0102] This embodiment provides a green Micro-LED epitaxial wafer, which includes a substrate, and a buffer layer, a first stress balancing layer, an undoped GaN layer, a second stress balancing layer, an N-type GaN layer, an electronic control layer, a multiple quantum well layer and a P-type GaN layer sequentially stacked on the substrate.

[0103] The substrate is sapphire, and the buffer layer is an AlN layer with a thickness of 35 nm. The first stress balancing layer is a Ga-type AlGaN layer with a thickness of 40 nm and an Al content of 0.15%. The thickness of the undoped GaN layer is 2.5 μm. The second stress balancing layer consists of alternating N-type GaN and N-type AlGaN layers with a total thickness of 85 nm and a period of 10. The thickness ratio of the N-type GaN layer to the N-type AlGaN layer is 9:1, and the Al content in the N-type AlGaN layer is 0.11%. The dopant element of the N-type GaN layer is Si, with a doping concentration of 8 × 10⁻⁶. 18 cm -3 Its thickness is 3μm.

[0104] The electronic control layer comprises alternating layers of Ga polar N-type AlInGaN and Ga polar N-type GaN, with a period number of 13. The Ga polar N-type AlInGaN layer has a thickness of 5 nm, an Al composition of 0.08%, an In composition of 0.03%, and a Si doping concentration of 3.3 × 10⁻⁶. 17 cm -3 The thickness of the Ga polar N-type GaN layer is 8 nm, and its Si doping concentration is 2.5 × 10⁻⁶. 17 cm -3The multiple quantum well layer consists of alternating layers of InGaN wells and GaN barriers. The InGaN wells have an In content of 0.25% and a thickness of 3 nm, while the GaN barriers have a thickness of 10 nm. The Mg doping concentration in the p-type GaN layer is 3 × 10⁻⁶. 20 cm -3 Its thickness is 150nm.

[0105] The method for fabricating the green Micro-LED epitaxial wafer in this embodiment includes the following steps:

[0106] (1) Provide a substrate.

[0107] (2) A buffer layer is grown on the substrate;

[0108] Among them, an AlN layer is grown by PVD as a buffer layer;

[0109] (3) A first stress balancing layer is grown on the buffer layer;

[0110] Among them, a Ga polar AlGaN layer is grown by MOCVD as the first stress balancing layer. The growth temperature is 1020℃ and the growth atmosphere is a mixed gas atmosphere of H2 and NH3 with a volume ratio of 1:1.5.

[0111] (4) An undoped GaN layer is grown on the first stress equilibrium layer;

[0112] Undoped GaN layers were grown using MOCVD at a temperature of 1120℃.

[0113] (5) A second stress-balancing layer is grown on the undoped GaN layer;

[0114] In this process, an N-polar GaN layer and an N-polar AlGaN layer are alternately grown by MOCVD to obtain a second stress-balanced layer. The growth temperature of the second stress-balanced layer is 1020℃, and the growth atmosphere is a mixed gas atmosphere of N2 and NH3 with a volume ratio of N2 to NH3 of 1:5.

[0115] (6) An N-type GaN layer is grown on the second stress equilibrium layer;

[0116] Among them, the N-type GaN layer was grown by MOCVD at a temperature of 1140℃.

[0117] (7) An electronic control layer is grown on an N-type GaN layer;

[0118] In this process, Ga polar N-type AlInGaN layers and Ga polar N-type GaN layers are alternately grown by MOCVD until an electronic control layer is obtained. The growth temperature of the electronic control layer is 980℃, and the growth atmosphere is a mixture of H2 and NH3 with a volume ratio of 1:6.

[0119] (8) Growing multiple quantum well layers on the electronic control layer;

[0120] In this process, InGaN well layers and GaN barrier layers are grown alternately using MOCVD until a multi-quantum well layer is obtained. The growth temperature of the InGaN well layer is 740℃, and the growth temperature of the GaN barrier layer is 880℃.

[0121] (9) Growing a P-type GaN layer on a multi-quantum-well layer;

[0122] Among them, the P-type GaN layer was grown by MOCVD at a growth temperature of 1030℃.

[0123] Example 2

[0124] This embodiment provides a green Micro-LED epitaxial wafer, which differs from Embodiment 1 in that:

[0125] The N-polar GaN layer is doped with Si at a concentration of 5.5 × 10⁻⁶. 17 cm -3 The N-polar AlGaN layer is doped with Si at a doping concentration of 1 × 10⁻⁶. 18 cm -3 .

[0126] Everything else is the same as in Example 1.

[0127] Example 3

[0128] This embodiment provides a green Micro-LED epitaxial wafer, which differs from Embodiment 1 in that:

[0129] Along the growth direction of the green Micro-LED epitaxial wafer, the Al composition in the Ga polar AlGaN layer shows an increasing change.

[0130] Everything else is the same as in Example 2.

[0131] Example 4

[0132] This embodiment provides a green Micro-LED epitaxial wafer, which differs from Embodiment 1 in that:

[0133] Along the growth direction of the green Micro-LED epitaxial wafer, the Al composition in the Ga polar N-type AlInGaN layer shows an increasing change.

[0134] Everything else is the same as in Example 3.

[0135] Example 5

[0136] This embodiment provides a green Micro-LED epitaxial wafer, which differs from Embodiment 4 in that:

[0137] The thickness of the buffer layer is 15nm.

[0138] After the buffer layer growth is completed, it is heat-treated at 1050℃ for 50s in a mixed gas atmosphere of H2, N2 and NH3. The volume ratio of H2, N2 and NH3 in the mixed gas is 1:1:1.5.

[0139] Everything else is the same as in Example 4.

[0140] Comparative Example 1

[0141] This comparative example provides a green Micro-LED epitaxial wafer, which differs from Example 1 in that:

[0142] Excluding the first stress balancing layer, the second stress balancing layer, and the electronic control layer.

[0143] A stress-relieving layer is provided between the N-type GaN layer and the multiple quantum well layer, which includes alternating layers of In. 0.05 Ga 0.95 N-layers and GaN layers, with a period of 18, In 0.05 Ga 0.95 The thickness of the N-layer is 3 nm, and the thickness of the GaN-layer is 3 nm. In 0.05 Ga 0.95 The growth temperature of the N layer is 880℃, and the growth temperature of the GaN layer is 950℃.

[0144] Everything else is the same as in Example 1.

[0145] Comparative Example 2

[0146] This comparative example provides a green Micro-LED epitaxial wafer, which differs from Example 1 in that:

[0147] Excluding the first stress balancing layer, the rest are the same as in Example 1.

[0148] Comparative Example 3

[0149] This comparative example provides a green Micro-LED epitaxial wafer, which differs from Example 1 in that:

[0150] Excluding the second stress balancing layer, everything else is the same as in Example 1.

[0151] Comparative Example 4

[0152] This comparative example provides a green Micro-LED epitaxial wafer, which differs from Example 1 in that:

[0153] Excluding the electronic control layer, everything else is the same as in Example 1.

[0154] The green Micro-LED epitaxial wafers obtained in Examples 1-5 and Comparative Examples 1-4 were used to fabricate a 50μm×50μm Micro-LED with a horizontal structure, achieving a 1A / cm² speed. 2 The luminous power and wavelength uniformity (PL-WD std) were tested at a current density, and the luminous power enhancement rate was calculated based on the data of Comparative Example 1. The specific results are shown in the table below:

[0155]

[0156] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A green Micro-LED epitaxial wafer, characterized in that, It includes a substrate, and a buffer layer, a first stress balancing layer, an undoped GaN layer, a second stress balancing layer, an N-type GaN layer, an electronic control layer, a multiple quantum well layer and a P-type GaN layer are sequentially stacked on the substrate. The first stress balancing layer is a Ga polar AlGaN layer with a thickness of 10 nm to 100 nm and an Al content of 0.01 to 0.2%. The second stress balancing layer comprises alternating layers of N polar GaN layers and N polar AlGaN layers, wherein the Al content in the N polar AlGaN layers is 0.01 to 0.15%. The electronic control layer comprises alternating layers of Ga polar N-type AlInGaN layers and Ga polar N-type GaN layers. The substrate is a sapphire substrate; The buffer layer is an AlN layer, which is grown by PVD; after growth, it is heat-treated in a mixed gas atmosphere of H2, N2 and NH3 at 1000℃~1100℃; wherein the volume ratio of H2, N2 and NH3 is 1:0.5:1~1:1:2; the thickness of the buffer layer is ≤20nm. Along the growth direction of the green Micro-LED epitaxial wafer, the Al composition in the Ga polar AlGaN layer shows an increasing change, and the Al composition in the Ga polar N-type AlInGaN layer also shows an increasing change.

2. The green Micro-LED epitaxial wafer as described in claim 1, characterized in that, The N-polar GaN layer is doped with Si at a concentration of 1 × 10⁻⁶. 17 cm -3 ~1×10 19 cm -3 ; The N-polar AlGaN layer is doped with Si at a concentration of 1 × 10⁻⁶. 17 cm -3 ~1×10 19 cm -3 .

3. The green Micro-LED epitaxial wafer as described in claim 1, characterized in that, The second stress balancing layer has 1 to 20 cycles; and / or The thickness of the second stress balancing layer is 10 nm to 100 nm, and the ratio of the thickness of the N-polar GaN layer to the thickness of the N-polar AlGaN layer is 1:1 to 10:1; and / or The period number of the electronic control layer is 1 to 20; and / or The thickness of the Ga polar N-type AlInGaN layer is 1 nm to 10 nm, with an Al content of 0.01% to 0.1% and an In content of 0.01% to 0.1%; the doping concentration is 1 × 10⁻⁶. 17 cm -3 ~1×10 18 cm -3 ; and / or The thickness of the Ga polar N-type GaN layer is 5nm~15nm, and the doping concentration is 1×10⁻⁶. 17 cm -3 ~1×10 18 cm -3 .

4. A method for fabricating a green Micro-LED epitaxial wafer, characterized in that, include: Provide substrate; A buffer layer is grown on the substrate; A first stress-balancing layer is grown on the buffer layer; An undoped GaN layer is grown on the first stress equilibrium layer; A second stress-balancing layer is grown on an undoped GaN layer; An N-type GaN layer is grown on the second stress equilibrium layer; An electronic control layer is grown on an N-type GaN layer; Growing a multi-quantum-well layer on an electronic control layer; Growing P-type GaN layers on multi-quantum-well layers; The substrate is a sapphire substrate; the first stress balancing layer is a Ga polar AlGaN layer with a thickness of 10nm~100nm and an Al content of 0.01~0.2%; the second stress balancing layer includes alternating layers of N polar GaN layers and N polar AlGaN layers, with the Al content in the N polar AlGaN layers being 0.01~0.15%; the electronic control layer includes alternating layers of Ga polar N-type AlInGaN layers and Ga polar N-type GaN layers. Along the growth direction of the green Micro-LED epitaxial wafer, the Al content in the Ga polar AlGaN layers increases, and the Al content in the Ga polar N-type AlInGaN layers also increases. The step of growing a buffer layer on the substrate includes: An AlN layer was grown using PVD as a buffer layer. The substrate with the AlN layer was heat-treated at 1000℃~1100℃ in a mixed gas atmosphere of H2, N2 and NH3; wherein the volume ratio of H2, N2 and NH3 was 1:0.5:1~1:1:

2. The thickness of the buffer layer is ≤20nm.

5. The method for preparing a green Micro-LED epitaxial wafer as described in claim 4, characterized in that, The growth temperature of the first stress balance layer is 1000℃~1100℃, and the growth atmosphere is a mixed gas atmosphere of H2 and NH3, with a volume ratio of H2 to NH3 of 1:1~1:

2.

6. The method for preparing a green Micro-LED epitaxial wafer as described in claim 4, characterized in that, The growth temperature of the second stress balancing layer is 50°C to 200°C lower than that of the undoped GaN layer. The growth atmosphere of the second stress balance layer is a mixed gas atmosphere of N2 and NH3, with a volume ratio of N2 to NH3 of 1:1 to 1:

10.

7. The method for preparing a green Micro-LED epitaxial wafer as described in claim 4, characterized in that, The growth temperature of the electronic control layer is 950℃~1080℃, and its growth atmosphere is a mixture of H2 and NH3, with a volume ratio of H2 to NH3 of 1:1~1:

10.

8. A green Micro-LED, characterized in that, Includes the green Micro-LED epitaxial wafer as described in any one of claims 1 to 3.

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