Micro-LED epitaxial wafer, preparation method thereof and Micro-LED

Abstract

The invention discloses a Micro-LED epitaxial wafer, a preparation method of the Micro-LED epitaxial wafer and a Micro-LED, and relates to the field of semiconductor photoelectric devices. The Micro-LED epitaxial wafer sequentially comprises a substrate, a buffer layer, a three-dimensional GaN layer, a first insertion layer, a two-dimensional GaN layer, an N-type GaN layer, a second insertion layer, a multi-quantum well layer and a P-type GaN layer. Wherein the first insertion layer comprises a BxGa1-xN layer and an AlGaN layer which are alternately stacked; the second insertion layer comprises a first superlattice layer and a second superlattice layer which are sequentially stacked on the N-type GaN layer, and the first superlattice layer comprises a ByGa1-yN layer and a Si3N4 layer which are alternately stacked; the second superlattice layer comprises an In < z > Ga < 1-z > N layer and a Si-doped GaN layer which are alternately stacked; wherein y < = x, z < = 0.1, and the thickness of the epitaxial layer < = 4.5 [mu] m. By implementing the invention, the luminous efficiency and the yield of the Micro-LED can be improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic devices, and more particularly to a Micro-LED epitaxial wafer and its fabrication 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 attracted widespread attention due to its excellent optoelectronic properties, particularly in applications such as light-emitting diodes (LEDs) and lasers. Currently, it shows great potential in Micro-LEDs (micro-display LEDs), but 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 Micro-LED epitaxial wafer with high luminous efficiency.

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

[0005] To address the aforementioned problems, this invention discloses a Micro-LED epitaxial wafer, comprising a substrate and an epitaxial layer disposed on the substrate; the epitaxial layer comprises a buffer layer, a three-dimensional GaN layer, a first insertion layer, a two-dimensional GaN layer, an N-type GaN layer, a second insertion layer, a multiple quantum well layer, and a P-type GaN layer sequentially stacked on the substrate. The first insertion layer includes alternating layers of B. x Ga 1-x N-layer and AlGaN layer; The second insertion layer includes a first superlattice layer and a second superlattice layer sequentially stacked on the N-type GaN layer, wherein the first superlattice layer includes alternating layers of B y Ga 1-y The second superlattice layer comprises alternating layers of N-layer and Si3N4-layer; z Ga 1-z N-layer and Si-doped GaN layer; Where y≤x, z≤0.1, and the thickness of the epitaxial layer≤4.5μm.

[0006] As an improvement to the above technical solution, the number of cycles in the first insertion layer is 2 to 15; The B x Ga 1-x The thickness of the N layer is 2nm~8nm, and the value of x ranges from 0.05 to 0.2; The AlGaN layer has a thickness of 2nm to 8nm and an Al content of 0.2% to 0.5%. The thickness of the three-dimensional GaN layer is ≤150nm; The thickness of the two-dimensional GaN layer is ≤1.5μm.

[0007] As an improvement to the above technical solution, the number of cycles in the first insertion layer is 3 to 10; The B x Ga 1-x The thickness of the N layer is 2nm~6nm, and the value of x ranges from 0.1 to 0.2; The AlGaN layer has a thickness of 2nm to 6nm and an Al content of 0.2% to 0.4%. The thickness of the three-dimensional GaN layer is 50nm~120nm; The thickness of the two-dimensional GaN layer is 0.8 μm to 1.2 μm.

[0008] As an improvement to the above technical solution, the number of periods in the first superlattice layer is 5 to 15; The B y Ga 1-y The thickness of the N layer is 1nm to 5nm, and the value of y ranges from 0.01 to 0.15. The thickness of the Si3N4 layer is 1nm~5nm; The number of periods in the second superlattice layer is 5 to 15; The In z Ga 1-z The thickness of the N layer is 1nm to 5nm, and the value of z ranges from 0.01 to 0.1. The thickness of the Si-doped GaN layer is 1 nm to 5 nm, and its Si doping concentration is 1 × 10⁻⁶. 17 cm -3 ~8×10 17 cm -3 .

[0009] As an improvement to the above technical solution, the multi-quantum well layer includes alternating layers of InGaN well layers and GaN barrier layers, with a period number of 3 to 12. The InGaN well layer has a thickness of 2nm to 4nm and an In composition ratio of 0.2% to 0.3%. The GaN barrier layer has a thickness of 5nm to 12nm.

[0010] As an improvement to the above technical solution, after the growth of the multi-quantum well layer is completed, multiple first V-holes and second V-holes are formed. The first V-hole is a single structure, and the second V-hole is obtained by merging at least two sub-V-holes.

[0011] As an improvement to the above technical solution, the width of the top of the first V-shaped crater is 100nm~150nm, and its distribution density is 5.5×10⁻⁶. 7 cm -2 ~8×10 7 cm -2 ; The width of the top of the second V-crater is 180nm~320nm, and its distribution density is 3.5×10⁻⁶. 7 cm -2 ~8.5×10 7 cm -2 .

[0012] Accordingly, the present invention also discloses a method for preparing a Micro-LED epitaxial wafer, comprising: Provide substrate; An epitaxial layer is grown on the substrate; The epitaxial layer includes a buffer layer, a three-dimensional GaN layer, a first insertion layer, a two-dimensional GaN layer, an N-type GaN layer, a second insertion layer, a multiple quantum well layer, and a P-type GaN layer, which are sequentially stacked on the substrate. The first insertion layer includes alternating layers of B. x Ga 1-x N-layer and AlGaN layer; The second insertion layer includes a first superlattice layer and a second superlattice layer sequentially stacked on the N-type GaN layer, wherein the first superlattice layer includes alternating layers of B y Ga 1-y The second superlattice layer comprises alternating layers of N-layer and Si3N4-layer; z Ga 1-z N-layer and Si-doped GaN layer; Where y≤x, z≤0.1, and the thickness of the epitaxial layer≤5μm.

[0013] As an improvement to the above technical solution, the B x Ga 1-x The growth temperature of the N layer is 900℃~1000℃, and the growth pressure is 200 torr~500 torr; The growth temperature of the AlGaN layer is 850℃~1000℃, and the growth pressure is 200 torr~500 torr; The B y Ga 1-yThe growth temperature of the N layer is 950℃~1100℃, and the growth pressure is 100 torr~300 torr; The growth temperature of the Si3N4 layer is 900℃~1100℃, and the growth pressure is 100 torr~300 torr. The In z Ga 1-z The growth temperature of the N layer is 780℃~850℃, and the growth pressure is 100 torr~300 torr; The growth temperature of the Si-doped GaN layer is 800℃~950℃, and the growth pressure is 100 torr~300 torr.

[0014] Accordingly, the present invention also discloses a Micro-LED, which includes the Micro-LED epitaxial wafer described above.

[0015] Implementing this invention has the following beneficial effects: An embodiment of the present invention provides a Micro-LED epitaxial wafer comprising a substrate, a buffer layer, a three-dimensional GaN layer, a first insertion layer, a two-dimensional GaN layer, an N-type GaN layer, a second insertion layer, a multiple quantum well layer, and a P-type GaN layer; wherein the first insertion layer comprises alternating layers of B... x Ga 1-x The second insertion layer comprises an N-type GaN layer and an AlGaN layer; the second insertion layer includes a first superlattice layer and a second superlattice layer sequentially stacked on the N-type GaN layer, the first superlattice layer comprising alternating layers of B... y Ga 1-y The second superlattice layer comprises alternating layers of N-layer and Si3N4-layer; z Ga 1-z N-layer and Si-doped GaN layer; where y≤x, z≤0.1. Based on the above embodiments, one approach is to introduce B into a conventional U-GaN layer. x Ga 1-x The first insertion layer, formed by alternating N-layers and AlGaN layers, effectively blocks the upward extension of dislocations, thereby effectively reducing the thickness of subsequent two-dimensional GaN layers. Even after this reduction, a low dislocation density is maintained, improving luminous efficiency. Furthermore, B... x Ga 1-x Both the N-layer and the AlGaN layer have high potential barriers, which effectively prevent electron overflow after reducing the thickness of the N-type GaN layer, confining electrons within the N-type GaN layer. In the first superlattice layer, B... y Ga 1-y The N-layer and Si3N4 layer can further block the extension of dislocations, preventing more dislocation defects from extending into the multi-quantum-well layer, weakening the polarization electric field, increasing the electron-hole recombination rate, and improving luminescence efficiency. Meanwhile, B... y Ga1-y The N-layer can also effectively reduce the electron migration rate, preventing them from overflowing into the p-type GaN layer and undergoing nonradiative recombination. Thirdly, the In in the second superlattice layer... z Ga 1-z The N-layer and Si-doped GaN-layer have a similar structure to the multi-quantum-well layer, effectively relieving stress and further reducing the intensity of the piezoelectric polarization field within the multi-quantum-well layer, thus improving luminescence efficiency. Furthermore, the Si-doped GaN-layer can further regulate the electron injection path, allowing for more uniform injection into the multi-quantum-well layer, thereby enhancing luminescence efficiency. Overall, based on the above epitaxial wafer structure, the overall thickness of the epitaxial layer can be reduced to below 4.5 μm, facilitating improved transfer yield while ensuring high luminescence efficiency of the epitaxial wafer. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a Micro-LED epitaxial wafer in one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a multi-quantum well layer in one embodiment of the present invention; Figure 3 This is a flowchart of a method for preparing a Micro-LED epitaxial wafer according to an embodiment of the present invention.

[0017] 100 is the substrate, 200 is the epitaxial layer, 210 is the buffer layer, 220 is the three-dimensional GaN layer, 230 is the first insertion layer, and 231 is the boron layer. x Ga 1-x N-layer, 232 is an AlGaN layer, 240 is a two-dimensional GaN layer, 250 is an N-type GaN layer, 260 is a second insertion layer, and 261 is a B-type GaN layer. y Ga 1-y N-layer, 262 is a Si3N4 layer, 263 is an In layer. z Ga 1-z N-layer, 264 is Si-doped GaN layer, 270 is multi-quantum well layer, 280 is P-type GaN layer, 310 is first V-pit, 320 is second V-pit, and 321 is sub-V-pit. Detailed Implementation

[0018] 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.

[0019] 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.

[0020] See Figure 1 As a first aspect of the present invention, a Micro-LED epitaxial wafer is disclosed, comprising a substrate 100 and an epitaxial layer 200 disposed on the substrate 100. The epitaxial layer 200 includes a buffer layer 210, a three-dimensional GaN layer 220, a first insertion layer 230, a two-dimensional GaN layer 240, an N-type GaN layer 250, a second insertion layer 260, a multiple quantum well layer 270, and a P-type GaN layer 280, which are sequentially stacked on the substrate 100.

[0021] The first insertion layer 230 includes alternating layers of B x Ga 1-x The N-layer 231 and the AlGaN layer 232, the second insertion layer 260 includes a first superlattice layer and a second superlattice layer sequentially stacked on the N-type GaN layer 250, the first superlattice layer including alternating layers of B y Ga 1-y N layer 261 and Si3N4 layer 262; the second superlattice layer comprises alternating layers of In z Ga 1-z N-layer 263 and Si-doped GaN layer 264, y≤x, z≤0.1. Based on the above technical solution, one approach is to introduce B into the traditional U-GaN layer. x Ga 1-x The first insertion layer 230, formed by alternating N-layer 231 and AlGaN layer 232, effectively blocks the upward extension of dislocations, thereby effectively reducing the thickness of the subsequent two-dimensional GaN layer 240. Even after this reduction, it maintains a low dislocation density, improving luminous efficiency. Furthermore, B... x Ga 1-x Both the N-layer 231 and the AlGaN layer 232 have high potential barriers, which can effectively prevent electron overflow after reducing the thickness of the N-type GaN layer 250, confining electrons within the N-type GaN layer 250. Both, in the first superlattice layer, B... y Ga 1-yThe N-layer 261 and Si3N4 layer 262 can further block the extension of dislocations, preventing more dislocation defects from extending into the multi-quantum-well layer 270, weakening the polarization electric field, increasing the electron-hole recombination rate, and improving luminescence efficiency. Meanwhile, B... y Ga 1-y The N-layer 261 can also effectively reduce the electron migration rate, preventing them from overflowing into the p-type GaN layer 280 and undergoing nonradiative recombination. Thirdly, the In in the second superlattice layer... z Ga 1-z The N-layer 263 and the Si-doped GaN layer 264 have a similar structure to the multi-quantum well layer 270, effectively relieving stress and further reducing the intensity of the piezoelectric polarization field within the multi-quantum well layer 270, thus improving luminous efficiency. Furthermore, the Si-doped GaN layer 264 can further regulate the electron injection path, allowing for more uniform injection into the multi-quantum well layer 270, thereby enhancing luminous efficiency. Overall, based on the above epitaxial wafer structure, the overall thickness of the epitaxial layer 200 can be reduced to below 4.5 μm, facilitating improved transfer yield while ensuring high luminous efficiency of the epitaxial wafer.

[0022] Specifically, the number of cycles in the first insertion layer 230 is 2 to 15, exemplarily 3, 5, 7, 9, 11, 13 or 15, but not limited thereto. Preferably it is 3 to 10.

[0023] Specifically, B x Ga 1-x The thickness of the N layer 231 is 2nm to 8nm, exemplarily 2.5nm, 4nm, 5.5nm, 7nm or 7.5nm, but not limited thereto. Preferably it is 2nm to 6nm.

[0024] B x Ga 1-x The proportion (i.e., x) of component B in layer N 231 is 0.05~0.2, exemplarily 0.08, 0.11, 0.14 or 0.17, but not limited thereto. Preferably it is 0.1~0.2.

[0025] Specifically, the thickness of the AlGaN layer 232 is 2nm to 8nm, exemplarily 2.5nm, 4nm, 5.5nm, 7nm or 7.5nm, but not limited thereto. Preferably, it is 2nm to 6nm.

[0026] The proportion of Al component in AlGaN layer 232 is 0.2~0.5, exemplary of which are 0.24, 0.28, 0.32, 0.36, 0.4, 0.44 or 0.48, but not limited thereto. Preferably it is 0.2~0.4.

[0027] Specifically, the number of periods in the first superlattice layer is 5 to 15, exemplarily 6, 8, 10, 12 or 14, but not limited thereto. Preferably it is 8 to 15.

[0028] Specifically, B y Ga 1-y The thickness of the N-layer 261 is 1nm to 5nm, exemplarily 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm, 4nm or 4.5nm, but not limited thereto. Preferably, it is 1nm to 3nm.

[0029] Specifically, B y Ga 1-y The proportion (i.e., y) of component B in layer N 261 is 0.01~0.15, exemplarily 0.03, 0.05, 0.07, 0.09, 0.11, 0.13 or 0.14, but not limited thereto. Preferably it is 0.02~0.08.

[0030] Specifically, the thickness of the Si3N4 layer 262 is 1nm to 5nm, exemplarily 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm, 4nm or 4.5nm, but not limited thereto. Preferably, it is 2nm to 5nm.

[0031] Specifically, the number of periods in the second superlattice layer is 5 to 15, exemplarily 6, 8, 10, 12 or 14, but not limited thereto. Preferably it is 8 to 15.

[0032] Specifically, in z Ga 1-z The thickness of the N-layer 263 is 1nm to 5nm, exemplarily 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm, 4nm or 4.5nm, but not limited thereto. Preferably, it is 2nm to 5nm.

[0033] In z Ga 1-z The proportion (i.e., z) of the In component in layer N 263 is 0.01 to 0.1, exemplarily 0.03, 0.05, 0.07 or 0.09, but not limited thereto. Preferably it is 0.01 to 0.05.

[0034] Specifically, the thickness of the Si-doped GaN layer 264 is 1 nm to 5 nm, exemplarily 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm or 4.5 nm, but not limited thereto. Preferably, it is 3 nm to 5 nm.

[0035] The Si doping concentration in the Si-doped GaN layer 264 is 1×10⁻⁶. 17 cm -3 ~8×10 17 cm-3 For example, 2.5 × 10 17 cm -3 4×10 17 cm -3 5.5×10 17 cm -3 Or 7×10 17 cm -3 However, it is not limited to this. Preferably, it is 3×10 17 cm -3 ~8×10 17 cm -3 .

[0036] Specifically, 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.

[0037] Specifically, the buffer layer 210 is an AlN layer or an AlGaN layer, but is not limited to these, and is preferably an AlN layer. The thickness of the buffer layer 210 is 10 nm to 80 nm.

[0038] Specifically, when growing GaN on the buffer layer 210, due to the presence of dislocation defects and the control of growth conditions, it can first be grown in three dimensions, thus obtaining a three-dimensional GaN layer 220. Specifically, the thickness of the three-dimensional GaN layer 220 is ≤150nm, preferably 50nm~120nm.

[0039] Specifically, the thickness of the two-dimensional GaN layer 240 is ≤1.5μm. Since this application introduces a specific first insertion layer 230, the requirements for dislocation annihilation in the three-dimensional GaN layer 220 and the two-dimensional GaN layer 240 are not high, so their heights are correspondingly reduced. More specifically, the height of the two-dimensional GaN layer 240 is 0.8μm~1.2μm.

[0040] Specifically, the N-type doping (Si) concentration in the N-type GaN layer 250 is 5 × 10⁻⁶. 18 cm -3 ~5×10 19 cm -3 Its thickness is 1μm~2μm. The thickness of the N-type GaN layer 250 in this technical solution is also relatively small.

[0041] Specifically, the multi-quantum-well layer 270 comprises alternating layers of InGaN wells and GaN barriers, with a period number of 3 to 15. The InGaN quantum well layers have an In content of 0.1% to 0.3% and a thickness of 2 nm to 4 nm, while the GaN barrier layers have a thickness of 5 nm to 12 nm. The Micro-LED epitaxial wafer of this application is suitable for blue, green, and yellow LEDs.

[0042] Specifically, the Mg doping concentration in the p-type GaN layer 280 is 1×10⁻⁶. 19 cm -3 ~1×10 21 cm -3 Its thickness is 20nm~120nm.

[0043] Preferably, in some embodiments, the In content in the InGaN well layer is 0.2% to 0.3%, meaning the Micro-LED is a green or yellow-green LED. When this In content ratio is used, the significant lattice difference between the InGaN well layer and the GaN barrier layer in the multi-quantum well layer 270 often easily induces V-pits. See [link to documentation]. Figure 2 The inventors discovered that, after the epitaxial wafer structure using this technical solution is completed, multiple first V-pits 310 and second V-pits 320 are formed after the multi-quantum well layer 270 is grown. The first V-pit 310 is a single structure, and the second V-pit 320 is formed by merging at least two sub-V-pits 321. Based on this structure, the injection efficiency of the hole injection multi-quantum well layer 270 can be effectively improved, dislocations can be shielded, luminescence efficiency can be improved, and wavelength shift and operating voltage can be reduced. More specifically, the width of the top of the first V-pit 310 is 100nm~150nm, and its distribution density is 5.5×10⁻⁶. 7 cm -2 ~8×10 7 cm -2 The width of the top of the second V-crater 320 is 180nm~320nm, and its distribution density is 3.5×10⁻⁶. 7 cm -2 ~8.5×10 7 cm -2 .

[0044] See Figure 3 As a second aspect of the present invention, the present invention also provides a method for preparing a Micro-LED epitaxial wafer, which specifically includes the following steps: S1: Provides a substrate; S2: Growing an epitaxial layer on the substrate; Specifically, step S2 includes: S21: Buffer layers are grown sequentially on the substrate; The buffer layer can be grown using PVD, MOCVD, MBE, or VPE, but is not limited to these methods.

[0045] Preferably, in some embodiments, an AlN layer is grown by PVD as a buffer layer.

[0046] More preferably, in some embodiments, S11 includes: S12: Growing a three-dimensional GaN layer on the buffer layer; Specifically, in some implementations, a three-dimensional GaN layer is grown by MOCVD at a growth temperature of 1000℃~1100℃, a growth pressure of 300 torr~500 torr, and a V / III ratio of 800~1200.

[0047] S13: Grow the first insertion layer on the three-dimensional GaN layer; Specifically, in some implementations, B is grown alternately by MOCVD. x Ga 1-x N-layers and AlGaN layers are added until the first insertion layer is obtained; where, B x Ga 1-x The growth temperature of the N layer is 900℃~1000℃, and the growth pressure is 200 torr~500 torr; the growth temperature of the AlGaN layer is 850℃~1000℃, and the growth pressure is 200 torr~500 torr.

[0048] S14: Grow a two-dimensional GaN layer on the first insertion layer; Specifically, in some implementations, a two-dimensional GAN ​​layer is grown by MOCVD at a growth temperature of 1050°C to 1150°C, a growth pressure of 20 torr to 200 torr, and a V / III ratio of 2000 to 3000.

[0049] S15: Growing an N-type GaN layer on a two-dimensional GaN layer; N-type GaN layers can be grown via MOCVD, MBE, or VPE, but are not limited to these methods.

[0050] Preferably, in some embodiments, an N-type GaN layer is grown by MOCVD; the growth temperature is 1100℃~1150℃ and the growth pressure is 100 torr~500 torr.

[0051] S16: Grow a second insertion layer on the N-type GaN layer; Specifically, in some implementations, a first superlattice layer and a second superlattice layer are grown sequentially by MOCVD to obtain a second insertion layer.

[0052] More specifically, B is first grown alternately via MOCVD. y Ga 1-y The first superlattice layer is obtained by growing N-layers and Si3N4 layers, followed by alternating growth of In. z Ga 1-z An N-layer and a Si-doped GaN-layer are used to obtain a second superlattice layer. Specifically, B y Ga 1-yThe growth temperature of the N layer is 950℃~1100℃, and the growth pressure is 100 torr~300 torr; the growth temperature of the Si3N4 layer is 900℃~1100℃, and the growth pressure is 100 torr~300 torr; In z Ga 1-z The growth temperature of the N layer is 780℃~850℃, and the growth pressure is 100 torr~300 torr; the growth temperature of the Si-doped GaN layer is 800℃~950℃, and the growth pressure is 100 torr~300 torr.

[0053] S17: Grow a multi-quantum-well layer on the second insertion layer; 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℃~780℃, and the growth pressure is 100 torr~300 torr; the growth temperature of the GaN barrier layer is 850℃~950℃, and the growth pressure is 100 torr~300 torr.

[0054] S18: Grow a P-type GaN layer on a multi-quantum-well layer; P-type GaN layers can be grown via MOCVD, MBE, or VPE, but are not limited to these methods.

[0055] Preferably, in some embodiments, a P-type GaN layer is grown by MOCVD at a growth temperature of 900°C to 1050°C and a growth pressure of 100 torr to 500 torr.

[0056] As a third aspect of the present invention, the present invention discloses a Micro-LED comprising the aforementioned Micro-LED epitaxial wafer.

[0057] The present invention will be further described below with reference to specific embodiments: Example 1 This embodiment provides a Micro-LED epitaxial wafer, which includes a substrate and an epitaxial layer disposed on the substrate. The epitaxial layer includes a buffer layer, a three-dimensional GaN layer, a first insertion layer, a two-dimensional GaN layer, an N-type GaN layer, a second insertion layer, a multiple quantum well layer and a P-type GaN layer, which are sequentially stacked on the substrate. The substrate is a sapphire substrate. The buffer layer is an AlN layer with a thickness of 30 nm. The three-dimensional GaN layer has a thickness of 140 nm. The first insertion layer consists of alternating layers of B... x Ga 1-x The structure consists of an N-layer (x=0.08) and an AlGaN layer, with a period number of 12. (B) x Ga 1-xThe thickness of the N-layer is 7 nm, and the thickness of the AlGaN layer is 7 nm. The thickness of the two-dimensional GaN layer is 1.45 μm. The thickness of the N-type GaN layer is 2.0 μm, and its Si doping concentration is 7.8 × 10⁻⁶. 18 cm -3 .

[0058] The second insertion layer comprises a first superlattice layer and a second superlattice layer sequentially stacked on an N-type GaN layer. The first superlattice layer comprises alternating layers of B y Ga 1-y The N-layer (y=0.08) and the Si3N4 layer have a period number of 6; B y Ga 1-y The thickness of the N layer is 4.5 nm, and the thickness of the Si3N4 layer is 4.5 nm. The second superlattice layer consists of alternating layers of In. z Ga 1-z The structure consists of an N-layer (z=0.06) and a Si-doped GaN layer with a period of 7; In z Ga 1-z The thickness of the N-layer is 3 nm, the thickness of the Si-doped GaN layer is 3 nm, and the Si doping concentration is 9 × 10⁻⁶. 17 cm -3 .

[0059] The multi-quantum-well layer comprises alternating layers of InGaN wells and GaN barriers, with a period number of 10. The InGaN well layer has an In content of 0.14% and a thickness of 3 nm, while the GaN barrier layer has 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 100nm.

[0060] The method for preparing the Micro-LED epitaxial wafer in this embodiment includes the following steps: (1) Provide a substrate.

[0061] (2) A buffer layer is grown on the substrate; Among them, an AlN layer is grown by PVD as a buffer layer; (3) A three-dimensional GaN layer is grown on the buffer layer; Specifically, a three-dimensional GaN layer was grown by MOCVD at a growth temperature of 1040℃, a growth pressure of 450 torr, and a V / Ⅲ ratio of 1000.

[0062] (4) Grow the first insertion layer on the three-dimensional GaN layer; Specifically, B is grown alternately via MOCVD. x Ga 1-x N-layers and AlGaN layers are added until the first insertion layer is obtained; where, B x Ga1-x The growth temperature of the N layer was 940℃ and the growth pressure was 500 torr; the growth temperature of the AlGaN layer was 880℃ and the growth pressure was 500 torr.

[0063] (5) A two-dimensional GaN layer is grown on the first insertion layer; Specifically, a two-dimensional GaN layer was grown by MOCVD at a growth temperature of 1120℃, a growth pressure of 100 torr, and a V / Ⅲ ratio of 2800.

[0064] (6) Growing an N-type GaN layer on a two-dimensional GaN layer; Specifically, an N-type GaN layer was grown by MOCVD at a temperature of 1140°C and a pressure of 200 torr.

[0065] (7) A second insertion layer is grown on the N-type GaN layer; Specifically, B is first grown alternately via MOCVD. y Ga 1-y The first superlattice layer is obtained by growing N-layers and Si3N4 layers, followed by alternating growth of In. z Ga 1-z An N-layer and a Si-doped GaN-layer are used to obtain a second superlattice layer. B y Ga 1-y The growth temperature of the N layer is 1090℃, and the growth pressure is 200 torr; the growth temperature of the Si3N4 layer is 980℃, and the growth pressure is 200 torr; In z Ga 1-z The growth temperature of the N layer is 810℃ and the growth pressure is 200 torr; the growth temperature of the Si-doped GaN layer is 920℃ and the growth pressure is 200 torr.

[0066] (8) Grow a multi-quantum-well layer on the second insertion layer; Specifically, 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 770℃ and the growth pressure is 200 torr; the growth temperature of the GaN barrier layer is 880℃ and the growth pressure is 200 torr.

[0067] (9) Growing a P-type GaN layer on a multi-quantum-well layer; Specifically, a P-type GaN layer was grown by MOCVD at a growth temperature of 1040℃ and a growth pressure of 200 torr.

[0068] Example 2 This embodiment provides a Micro-LED epitaxial wafer, which differs from Embodiment 1 in that: The thickness of the three-dimensional GaN layer is 100 nm. The first insertion layer consists of alternating layers of B... x Ga 1-x The structure consists of an N-layer (x=0.12) and an AlGaN layer, with a period number of 10. (B) x Ga 1-x The thickness of the N-layer is 5 nm, the thickness of the AlGaN layer is 5 nm, the thickness of the two-dimensional GaN layer is 1.2 μm, and the thickness of the N-type GaN layer is 1.5 μm.

[0069] The second insertion layer comprises a first superlattice layer and a second superlattice layer sequentially stacked on an N-type GaN layer. The first superlattice layer comprises alternating layers of B y Ga 1-y The N-layer (y=0.05) and the Si3N4 layer have a period number of 10; B y Ga 1-y The N-layer has a thickness of 3 nm, and the Si3N4 layer has a thickness of 5 nm. The second superlattice layer consists of alternating layers of In. z Ga 1-z The N-layer (z=0.03) and the Si-doped GaN layer have a period number of 12; In z Ga 1-z The thickness of the N-layer is 3 nm, the thickness of the Si-doped GaN layer is 3 nm, and the Si doping concentration is 9 × 10⁻⁶. 17 cm -3 .

[0070] Everything else is the same as in Example 1.

[0071] Example 3 This embodiment provides a Micro-LED epitaxial wafer, which includes a substrate and an epitaxial layer disposed on the substrate. The epitaxial layer includes a buffer layer, a three-dimensional GaN layer, a first insertion layer, a two-dimensional GaN layer, an N-type GaN layer, a second insertion layer, a multiple quantum well layer and a P-type GaN layer, which are sequentially stacked on the substrate. The substrate is a sapphire substrate. The buffer layer is an AlN layer with a thickness of 40 nm. The three-dimensional GaN layer has a thickness of 150 nm. The first insertion layer consists of alternating layers of B... x Ga 1-x The structure consists of an N-layer (x=0.08) and an AlGaN layer, with a period number of 12. (B) x Ga 1-x The thickness of the N-layer is 7 nm, and the thickness of the AlGaN layer is 7 nm. The thickness of the two-dimensional GaN layer is 1.5 μm. The thickness of the N-type GaN layer is 2.0 μm, and its Si doping concentration is 7.8 × 10⁻⁶. 18 cm -3 .

[0072] The second insertion layer comprises a first superlattice layer and a second superlattice layer sequentially stacked on an N-type GaN layer. The first superlattice layer comprises alternating layers of B y Ga 1-y The N-layer (y=0.08) and the Si3N4 layer have a period number of 6; B y Ga 1-y The thickness of the N layer is 4.5 nm, and the thickness of the Si3N4 layer is 4.5 nm. The second superlattice layer consists of alternating layers of In. z Ga 1-z The structure consists of an N-layer (z=0.06) and a Si-doped GaN layer with a period of 7; In z Ga 1-z The thickness of the N-layer is 3 nm, the thickness of the Si-doped GaN layer is 3 nm, and the Si doping concentration is 9 × 10⁻⁶. 17 cm -3 .

[0073] The multi-quantum-well layer comprises alternating layers of InGaN wells and GaN barriers, with a period of 10. The InGaN well layer has an In content of 0.25% and a thickness of 3 nm, while the GaN barrier layer has 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 100nm.

[0074] After the multi-quantum well layer is grown, multiple first V-pits and second V-pits are formed. The first V-pit is a single structure, and the second V-pit is formed by merging at least two sub-V-pits. The width of the top of the first V-pit is 125~140nm, and its distribution density is 7.3×10⁻⁶. 7 cm -2 The width of the top of the second V-crater is 240 nm to 275 nm, and its distribution density is 4.1 × 10⁻⁶. 7 cm -2 .

[0075] The method for preparing the Micro-LED epitaxial wafer in this embodiment includes the following steps: (1) Provide a substrate.

[0076] (2) A buffer layer is grown on the substrate; Among them, an AlN layer is grown by PVD as a buffer layer; (3) A three-dimensional GaN layer is grown on the buffer layer; Specifically, a three-dimensional GaN layer was grown by MOCVD at a growth temperature of 1040℃, a growth pressure of 450 torr, and a V / Ⅲ ratio of 1000.

[0077] (4) Grow the first insertion layer on the three-dimensional GaN layer; Specifically, B is grown alternately via MOCVD. x Ga 1-x N-layers and AlGaN layers are added until the first insertion layer is obtained; where, B x Ga 1-x The growth temperature of the N layer was 940℃ and the growth pressure was 500 torr; the growth temperature of the AlGaN layer was 880℃ and the growth pressure was 500 torr.

[0078] (5) A two-dimensional GaN layer is grown on the first insertion layer; Specifically, a two-dimensional GaN layer was grown by MOCVD at a growth temperature of 1120℃, a growth pressure of 100 torr, and a V / Ⅲ ratio of 2800.

[0079] (6) Growing an N-type GaN layer on a two-dimensional GaN layer; Specifically, an N-type GaN layer was grown by MOCVD at a temperature of 1140°C and a pressure of 200 torr.

[0080] (7) A second insertion layer is grown on the N-type GaN layer; Specifically, B is first grown alternately via MOCVD. y Ga 1-y The first superlattice layer is obtained by growing N-layers and Si3N4 layers, followed by alternating growth of In. z Ga 1-z An N-layer and a Si-doped GaN-layer are used to obtain a second superlattice layer. B y Ga 1-y The growth temperature of the N layer is 1090℃, and the growth pressure is 200 torr; the growth temperature of the Si3N4 layer is 980℃, and the growth pressure is 200 torr; In z Ga 1-z The growth temperature of the N layer is 810℃ and the growth pressure is 200 torr; the growth temperature of the Si-doped GaN layer is 920℃ and the growth pressure is 200 torr.

[0081] (8) Grow a multi-quantum-well layer on the second insertion layer; Specifically, 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 740℃ and the growth pressure is 200 torr; the growth temperature of the GaN barrier layer is 880℃ and the growth pressure is 200 torr.

[0082] (9) Growing a P-type GaN layer on a multi-quantum-well layer; Specifically, a P-type GaN layer was grown by MOCVD at a growth temperature of 1040℃ and a growth pressure of 200 torr.

[0083] Example 4 This embodiment provides a Micro-LED epitaxial wafer, which differs from Embodiment 3 in that: The thickness of the three-dimensional GaN layer is 120 nm. The first insertion layer consists of alternating layers of B... x Ga 1-x The structure consists of an N-layer (x=0.13) and an AlGaN layer, with a period number of 10. (B) x Ga 1-x The thickness of the N-layer is 6 nm, and the thickness of the AlGaN layer is 5 nm. The thickness of the two-dimensional GaN layer is 1.2 μm. The thickness of the N-type GaN layer is 1.8 μm.

[0084] The second insertion layer comprises a first superlattice layer and a second superlattice layer sequentially stacked on an N-type GaN layer. The first superlattice layer comprises alternating layers of B y Ga 1-y The N-layer (y=0.05) and the Si3N4 layer have a period number of 10; B y Ga 1-y The N-layer has a thickness of 3 nm, and the Si3N4 layer has a thickness of 5 nm. The second superlattice layer consists of alternating layers of In. z Ga 1-z The N-layer (z=0.03) and the Si-doped GaN layer have a period number of 12; In z Ga 1-z The thickness of the N-layer is 3 nm, the thickness of the Si-doped GaN layer is 3 nm, and the Si doping concentration is 9 × 10⁻⁶. 17 cm -3 .

[0085] After the multi-quantum well layer is grown, multiple first V-pits and second V-pits are formed. The first V-pit is a single structure, and the second V-pit is formed by merging at least two sub-V-pits. The width of the top of the first V-pit is 120~145nm, and its distribution density is 5.8×10⁻⁶. 7 cm -2 The width of the top of the second V-crater is 270 nm to 312 nm, and its distribution density is 5.5 × 10⁻⁶. 7 cm -2 .

[0086] Everything else is the same as in Example 3.

[0087] Comparative Example 1 This comparative example provides a Micro-LED epitaxial wafer, which differs from Example 1 in that: Excluding the first and second insertion layers.

[0088] Everything else is the same as in Example 1.

[0089] Comparative Example 2 This comparative example provides a Micro-LED epitaxial wafer, which differs from Example 1 in that: Excluding the first insertion layer, the rest are the same as in Example 1.

[0090] Comparative Example 3 This comparative example provides a Micro-LED epitaxial wafer, which differs from Example 1 in that: Excluding the second insertion layer, everything else is the same as in Example 1.

[0091] Comparative Example 4 This comparative example provides a Micro-LED epitaxial wafer, which differs from Example 1 in that: Excluding the first superlattice layer, the rest are the same as in Example 1.

[0092] The Micro-LED epitaxial wafers obtained in Examples 1-4 and Comparative Examples 1-4 were used to fabricate Micro-LEDs with a horizontal structure, measuring 50 μm × 50 μm, and operating at 1 A / cm². 2 The luminous power and wavelength uniformity (PL-WDstd) were tested at a given current density, and the luminous power enhancement rate was calculated based on the data from Comparative Example 1. The specific results are shown in the table below:

[0093] 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 Micro-LED epitaxial wafer, characterized in that, The epitaxial layer comprises a buffer layer, a three-dimensional GaN layer, a first interlayer, a two-dimensional GaN layer, an N-type GaN layer, a second interlayer, a multi-quantum well layer, and a P-type GaN layer, which are sequentially stacked on the substrate. wherein the first insertion layer includes B x Ga 1-x N layers and AlGaN layers; The second insertion layer comprises a first superlattice layer and a second superlattice layer which are sequentially stacked on the N-type GaN layer, the first superlattice layer comprises B y Ga 1-y N layers and Si3N4 layers which are alternately stacked; and the second superlattice layer comprises In z Ga 1-z N layers and Si-doped GaN layers which are alternately stacked. Wherein, y≤x, z≤0.1, and the thickness of the epitaxial layer is ≤4.5 μm.

2. The Micro-LED epiwafer of claim 1, wherein, The period number of the first interlayer is 2-15. The B x Ga 1-x The thickness of the GaN layer is 2-8 nm, and x is 0.05-0.

2. The thickness of the AlGaN layer is 2-8 nm, and the proportion of Al component is 0.2-0.

5. The thickness of the three-dimensional GaN layer is ≤150 nm. The thickness of the two-dimensional GaN layer is ≤1.5 μm.

3. The Micro-LED epiwafer of claim 1, wherein, The period number of the first interlayer is 3-10. The B x Ga 1-x The thickness of the N layer is 2-6 nm, and the value range of x is 0.1-0.

2. The thickness of the AlGaN layer is 2-6 nm, and the proportion of Al component is 0.2-0.

4. The thickness of the three-dimensional GaN layer is 50-120 nm. The thickness of the two-dimensional GaN layer is 0.8-1.2 μm.

4. The Micro-LED epiwafer of claim 1, wherein, The period number of the first superlattice layer is 5-15. The B y Ga 1-y The thickness of the GaN layer is 1 nm to 5 nm, and the value range of y is 0.01 to 0.

15. The thickness of the Si3N4 layer is 1-5 nm. The period number of the second superlattice layer is 5-15. The In z Ga 1-z The thickness of the N layer is 1 nm-5 nm, and the value range of z is 0.01-0.

1. The Si-doped GaN layer has a thickness of 1 nm to 5 nm and a Si doping concentration of 1 x 10 17 cm -3 ~8 x 10 17 cm -3 .

5. The Micro-LED epiwafer of claim 1, wherein, The multi-quantum well layer comprises alternately stacked InGaN well layers and GaN barrier layers, and the period number is 3-12. The thickness of the InGaN well layer is 2-4 nm, and the proportion of In component is 0.2-0.3; the thickness of the GaN barrier layer is 5-12 nm.

6. The Micro-LED epiwafer of claim 5, wherein, After the growth of the multi-quantum well layer, a plurality of first V-pits and second V-pits are formed, the first V-pit is a single structure, and the second V-pit is obtained by merging at least two sub-V-pits.

7. The Micro-LED epiwafer of claim 6, wherein, The width of the top of the first V-pit is 100-150 nm, and the distribution density is 5.5*10 7 cm -2 ~8*10 7 cm -2 ; The width of the top of the second V-pit is 180-320 nm, and the distribution density is 3.5*10 7 cm -2 ~8.5*10 7 cm -2 .

8. A preparation method of a Micro-LED epitaxial wafer, characterized in that, The method comprises: providing a substrate; growing an epitaxial layer on the substrate; The epitaxial layer comprises a buffer layer, a three-dimensional GaN layer, a first interlayer, a two-dimensional GaN layer, an N-type GaN layer, a second interlayer, a multi-quantum well layer, and a P-type GaN layer, which are sequentially stacked on the substrate. wherein the first insertion layer includes B x Ga 1-x N layers and AlGaN layers; The second insertion layer comprises a first superlattice layer and a second superlattice layer which are sequentially stacked on the N-type GaN layer, the first superlattice layer comprises B y Ga 1-y N layers and Si3N4 layers which are alternately stacked; and the second superlattice layer comprises In z Ga 1-z N layers and Si-doped GaN layers which are alternately stacked. Wherein, y≤x, z≤0.1, and the thickness of the epitaxial layer is ≤5 μm.

9. The preparation method of the Micro-LED epitaxial wafer according to claim 8, characterized in that, The B x Ga 1-x The growth temperature of the N layer is 900-1000℃, and the growth pressure is 200-500 torr. The growth temperature of the AlGaN layer is 850-1000℃, and the growth pressure is 200-500 torr; The B y Ga 1-y The growth temperature of the N layer is 950-1100℃, and the growth pressure is 100-300 torr. The growth temperature of the Si3N4 layer is 900-1100℃, and the growth pressure is 100-300 torr; The In z Ga 1-z The growth temperature of the N layer is 780-850℃, and the growth pressure is 100-300 torr. The growth temperature of the Si-doped GaN layer is 800-950℃, and the growth pressure is 100-300 torr.

10. A micro-LED, comprising: The Micro-LED epitaxial wafer comprises any one of the Micro-LED epitaxial wafers according to claims 1-7.

Images