Light emitting diode epitaxial wafer and preparation method thereof, and light emitting diode

Abstract

The application discloses a light emitting diode epitaxial wafer and a preparation method thereof and a light emitting diode, wherein the light emitting diode epitaxial wafer comprises a substrate, a composite buffer layer, a non-doped GaN layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer which are sequentially stacked on the substrate, the composite buffer layer comprises a first buffer layer and a second buffer layer, the first buffer layer comprises a Ga2O3 layer and an (AlGa)2O3 layer which are sequentially stacked, the second buffer layer comprises a first GaN layer and a second GaN layer which are periodically and alternately stacked, and the first GaN layer and the second GaN layer are both two-dimensional GaN layers. The composite buffer layer can reduce the electric leakage channel caused by the substrate and the defects caused by the lattice mismatch between the substrate and GaN, thereby improving the light emitting efficiency.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a light-emitting diode epitaxial wafer and its fabrication method, and a light-emitting diode. Background Technology

[0002] GaN-based LEDs possess attributes such as a large bandgap and excellent breakdown voltage, and have been widely used in high-power devices. However, during the epitaxial growth of LEDs, there is a significant lattice mismatch and thermal mismatch between the epitaxial layer and the substrate, which further reduces the crystal quality of the subsequently grown epitaxial layer, thus affecting its photoelectric performance.

[0003] In the existing epitaxial growth process of GaN-based LEDs on Si substrates, an AlN buffer layer is usually grown on the substrate first to prevent meltback etching between the Si substrate and the GaN epitaxial layer. However, there is still a large lattice mismatch and thermal mismatch between the AlN buffer layer and the substrate, which will generate a large number of dislocations. At the same time, the GaN epitaxial layer will also be subjected to large tensile stress. In addition, the substrate will also cause electron migration, resulting in leakage channels, which will seriously reduce the epitaxial quality of GaN-based LEDs and the performance of LED devices. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a light-emitting diode epitaxial wafer that can reduce leakage channels caused by the substrate and defects caused by lattice mismatch between the substrate and GaN, thereby improving luminous efficiency.

[0005] The technical problem to be solved by the present invention is to provide a method for preparing an epitaxial wafer of a light-emitting diode, which is simple in process and produces an epitaxial wafer of a light-emitting diode with high luminous efficiency.

[0006] To achieve the above-mentioned technical effects, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate and a composite buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer and a P-type GaN layer sequentially stacked on the substrate. The composite buffer layer comprises a first buffer layer and a second buffer layer. The first buffer layer comprises a Ga2O3 layer and a (AlGa)2O3 layer sequentially stacked. The second buffer layer comprises a first GaN layer and a second GaN layer periodically alternatingly stacked. Both the first GaN layer and the second GaN layer are two-dimensional GaN layers.

[0007] As an improvement to the above technical solution, the thickness of the Ga2O3 layer is 1nm to 10nm;

[0008] The thickness of the (AlGa)2O3 layer is 10nm to 100nm.

[0009] As an improvement to the above technical solution, the Al composition ratio of the (AlGa)2O3 layer is 0.1 to 0.4.

[0010] As an improvement to the above technical solution, the first GaN layer is a Mg-doped GaN layer with a thickness of 5nm to 10nm and a Mg doping concentration of 1×10⁻⁶. 15 cm -3 ~1×10 16 cm -3 The thickness of the second GaN layer is 5nm to 10nm.

[0011] As an improvement to the above technical solution, the growth cycle of the second buffer layer is 5 to 8 days.

[0012] Accordingly, the present invention also discloses a method for preparing a light-emitting diode epitaxial wafer, which includes the following steps:

[0013] A substrate is provided on which a composite buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, and a P-type GaN layer are sequentially grown. The composite buffer layer includes a first buffer layer and a second buffer layer. The first buffer layer includes a Ga2O3 layer and a (AlGa)2O3 layer stacked sequentially. The second buffer layer includes a first GaN layer and a second GaN layer stacked periodically and alternately. Both the first GaN layer and the second GaN layer are two-dimensional GaN layers.

[0014] As an improvement to the above technical solution, the Ga2O3 layer is grown using PLD, with a growth temperature of 600℃~650℃ and a growth pressure of 10. -5 mbar ~ 10 -2 mbar, laser pulse frequency of 2Hz~3Hz, laser energy density of 1.5J / cm² 2 ~2.5J / cm 2 .

[0015] As an improvement to the above technical solution, the (AlGa)₂O₃ layer is grown using PLD, with the growth temperature of the (AlGa)₂O₃ layer ranging from 610℃ to 800℃ and the growth pressure being 10... -5 mbar ~ 10 -2 mbar, laser pulse frequency of 2Hz~3Hz, laser energy density of 1.5J / cm² 2 ~2.5J / cm 2 .

[0016] As an improvement to the above technical solution, the second buffer layer is grown by MOCVD, and the growth temperature of the second buffer layer is 800℃~1000℃, and the growth pressure is 200Torr~300Torr.

[0017] Accordingly, the present invention also discloses a light-emitting diode, including the above-mentioned light-emitting diode epitaxial wafer.

[0018] Implementing the embodiments of the present invention has the following beneficial effects:

[0019] The composite buffer layer of this invention includes a first buffer layer and a second buffer layer. The (AlGa)2O3 layer in the first buffer layer has a high bandgap, which can effectively prevent electron migration and reduce leakage channels. The Ga2O3 layer can improve the crystal quality of the (AlGa)2O3 layer and avoid the generation of polycrystalline materials. The first buffer layer also prevents the reaction between NH3 and the Si substrate and the remelting etching phenomenon between Ga and the Si substrate, thus improving the crystal quality of the GaN epitaxial layer. The two-dimensional structure of the second buffer layer provides a flat nucleation surface for further growth, reduces the contact angle of nucleation growth, and enables the island-grown GaN grains to connect into a surface within a small thickness, transforming into two-dimensional epitaxial growth, which improves the crystal quality of the subsequently deposited GaN epitaxial layer. The superlattice structure can continuously twist the direction of dislocations at the interface, thereby intersecting, reducing the dislocation density of the epitaxial layer, improving the crystal quality of the GaN epitaxial layer, reducing non-radiative recombination caused by defects, and improving the luminous efficiency of the light-emitting diode. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the light-emitting diode epitaxial wafer provided in an embodiment of the present invention;

[0021] Figure 2 This is a flowchart of the method for fabricating a light-emitting diode epitaxial wafer provided in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0023] like Figure 1As shown, this embodiment of the invention provides a light-emitting diode epitaxial wafer, including a substrate 1 and a composite buffer layer 2, an undoped GaN layer 3, an N-type GaN layer 4, a multiple quantum well layer 5, an electron blocking layer 6, and a P-type GaN layer 7 sequentially stacked on the substrate 1. The composite buffer layer 2 includes a first buffer layer 21 and a second buffer layer 22. The first buffer layer 21 includes a Ga2O3 layer and a (AlGa)2O3 layer sequentially stacked, and the second buffer layer 22 includes a first GaN layer and a second GaN layer periodically alternatingly stacked. Both the first GaN layer and the second GaN layer are two-dimensional GaN layers. The (AlGa)2O3 layer in the first buffer layer has a high bandgap, which can effectively prevent electron migration from the substrate, thereby reducing leakage channels. The Ga2O3 layer can improve the crystal quality of the (AlGa)2O3 layer and avoid the generation of polycrystalline materials. The first buffer layer also prevents the reaction between NH3 and the Si substrate and the remelting etching phenomenon between Ga and Si, thus improving the crystal quality of the GaN epitaxial layer. The two-dimensional structure of the second buffer layer provides a flat nucleation surface for further growth, reduces the contact angle of nucleation growth, and enables the island-grown GaN grains to connect into a surface within a smaller thickness, transforming into two-dimensional epitaxial growth, thereby improving the crystal quality of the subsequently deposited GaN epitaxial layer.

[0024] In one embodiment, the thickness of the Ga2O3 layer is 1 nm to 10 nm. The presence of the Ga2O3 layer reduces the lattice mismatch between the (AlGa)2O3 film and the substrate, improves the crystal quality of the (AlGa)2O3 film, and avoids the formation of polycrystalline structures. If the thickness is too small, the large crystal grains will hinder the growth of the Ga2O3 layer, thus affecting the quality of the subsequently grown (AlGa)2O3 layer. Examples of thicknesses are 1 nm, 3 nm, 5 nm, 6 nm, 8 nm, or 10 nm, but are not limited to these. The thickness of the (AlGa)2O3 layer is 10 nm to 100 nm. If the thickness is less than 10 nm, it is not conducive to improving uniformity; if the thickness is greater than 100 nm, it will cause a decrease in quality. Examples of thicknesses are 10 nm, 30 nm, 50 nm, 60 nm, 80 nm, or 100 nm, but are not limited to these.

[0025] In one embodiment, the Al content of the (AlGa)2O3 layer is 0.1 to 0.4. Increasing the Al content in Ga2O3 to form (AlGa)2O3 material can increase the band gap and effectively prevent electron mobility, thereby reducing the generation of leakage channels. If the Al content is less than 0.1, the blocking effect on electrons is not obvious; if the Al content is greater than 0.4, it will cause a decrease in crystal quality. Examples of Al content are 0.1, 0.15, 0.2, 0.25, 0.3 or 0.4, but not limited to these.

[0026] In one embodiment, the growth cycle of the second buffer layer is 5 to 8, exemplarily 5, 6, 7, or 8. The first GaN layer is a two-dimensional Mg-doped GaN layer with a thickness of 5 nm to 10 nm, exemplarily 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or 10 nm, but not limited thereto. The Mg doping concentration of the first GaN layer is 1 × 10⁻⁶. 15 cm -3 ~1×10 16 cm -3 Holes generated by Mg doping can reduce electron migration from the substrate, decrease leakage channels, enhance antistatic properties, effectively reduce the resistivity of the epitaxial layer, and lower the operating voltage of the LED. If the Mg doping concentration is less than 1×10⁻⁶, the resulting holes can reduce electron migration from the substrate, decrease leakage current channels, enhance antistatic properties, effectively lower the resistivity of the epitaxial layer, and reduce the operating voltage of the LED. 15 cm -3 It cannot provide enough holes to reduce electron migration from the substrate; if the Mg doping concentration is greater than 1×10 16 cm -3 This will cause a decrease in crystal quality and affect the quality of subsequent epitaxial structures; an example is 1×10⁻⁶. 15 cm -3 2.5×10 15 cm -3 5×10 15 cm -3 8×10 15 cm -3 Or 1×10 16 cm -3 However, this is not the only limitation. The second GaN layer is a two-dimensional GaN layer with a thickness of 5nm to 10nm, exemplarily 5nm, 6nm, 7nm, 8nm, 9nm, or 10nm, but not limited to these. By setting the second buffer layer as a superlattice structure and controlling the thickness and growth cycle of the first and second GaN layers in each cycle, the direction of dislocations can be continuously reversed at the interface, thereby annihilating dislocations, reducing the dislocation density of the epitaxial layer, improving the crystal quality of the GaN epitaxial layer, reducing nonradiative recombination caused by defects, and improving the luminous efficiency of the light-emitting diode.

[0027] In addition to the composite buffer layer structure described above, the other layered structures of the present invention have the following characteristics:

[0028] The substrate 1 can be selected from one of the following: sapphire substrate, SiO2 sapphire composite substrate, silicon substrate, silicon carbide substrate, gallium nitride substrate, and zinc oxide substrate. Specifically, the substrate 1 is selected as a Si substrate, which has large size, low price, and can simplify the substrate thinning process and reduce the epitaxial growth cost.

[0029] The thickness of the undoped GaN layer 3 is 1 μm to 5 μm.

[0030] The thickness of the N-type GaN layer 4 is 2μm to 3μm, and the Si doping concentration is 1×10⁻⁶. 19 cm -3 ~5×10 19 cm -3 .

[0031] The multi-quantum-well layer 5 comprises periodically stacked InGaN quantum well layers and AlGaN quantum barrier layers, with a stacking period of 6 to 12. The InGaN quantum well layer has a thickness of 2 nm to 5 nm and an In composition ratio of 0.1 to 0.3; the AlGaN quantum barrier layer has a thickness of 5 nm to 15 nm and an Al composition ratio of 0.01 to 0.1.

[0032] The electron blocking layer 6 is an AlInGaN layer with a thickness of 10nm to 40nm, an Al content of 0.005 to 0.1%, and an In content of 0.01 to 0.2%.

[0033] The thickness of the p-type GaN layer 7 is 10 nm to 50 nm, and the Mg doping concentration is 1 × 10⁻⁶. 19 cm -3 ~1×10 21 cm -3 .

[0034] Correspondingly, such as Figure 2 As shown, the present invention also provides a method for fabricating a light-emitting diode epitaxial wafer, comprising the following steps:

[0035] S1. Provide a substrate;

[0036] In one embodiment, a Si substrate is selected as the substrate.

[0037] S2. A composite buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, and a P-type GaN layer are sequentially grown on the substrate. The epitaxial structure can be grown using MOCVD, MBE, PLD, or VPE, but is not limited to these methods. Specifically, S2 includes the following steps:

[0038] S21, Growing a composite buffer layer; specifically, S21 includes the following steps:

[0039] S211, Growth of the first buffer layer;

[0040] PLD growth was employed, with the reaction chamber temperature controlled at 600℃~650℃ and the pressure at 10. -5 mbar ~ 10 -2 mbar, laser pulse frequency of 2Hz~3Hz, laser energy density of 1.5J / cm² 2 ~2.5J / cm 2The target material is Ga2O3, and a Ga2O3 layer is grown; PLD growth is used, and the reaction chamber temperature is controlled at 610℃~800℃, and the pressure is 10. -5 mbar ~ 10 -2 mbar, laser pulse frequency of 2Hz~3Hz, laser energy density of 1.5J / cm² 2 ~2.5J / cm 2 The target material is Ga2O3 with an Al content of 12% atomic ratio, and an (AlGa)2O3 layer is grown.

[0041] S212, grow the second buffer layer;

[0042] MOCVD growth was employed, with the reaction chamber temperature controlled at 800℃~1000℃ and the pressure at 200Torr~300Torr. NH3 was introduced as the N source, TMGa as the Ga source, and Cp2Mg as the P-type doping source to grow the first GaN layer. The reaction chamber temperature was then controlled at 800℃~1000℃ and the pressure at 200Torr~300Torr, with NH3 as the N source and TMGa as the Ga source to grow the second GaN layer. The first and second GaN layers were then periodically grown by repeated stacking.

[0043] S22, grow an undoped GaN layer;

[0044] MOCVD growth was employed, with the reaction chamber temperature controlled at 1050℃~1200℃ and the pressure at 100Torr~600Torr. NH3 was introduced as the N source, and TMGa was introduced as the Ga source.

[0045] S23, grow an N-type GaN layer;

[0046] MOCVD growth was employed, with the reaction chamber temperature controlled at 1050℃~1200℃ and the pressure at 100Torr~600Torr. NH3 was introduced as the N source, TMGa as the Ga source, and SiH4 as the N-type doping source.

[0047] S24, Growth of multiple quantum well layers;

[0048] MOCVD was used to grow InGaN quantum well layers, with the reaction chamber temperature controlled at 790℃~810℃ and the pressure at 50Torr~300Torr. NH3 was introduced as the N source, TMGa as the Ga source, and TMIn as the In source. AlGaN quantum barrier layers were grown by controlling the reaction chamber temperature at 800℃~900℃ and the pressure at 50Torr~300Torr, with NH3 as the N source, TMGa as the Ga source, and TMAl as the Al source. InGaN quantum well layers and AlGaN quantum barrier layers were then repeatedly stacked and periodically grown.

[0049] S25, growth of electron blocking layer;

[0050] MOCVD growth was employed, with the reaction chamber temperature controlled at 900℃~1000℃ and the pressure at 100Torr~300Torr. NH3 was introduced as the N source, TMGa as the Ga source, TMAl as the Al source, and TMIn as the In source.

[0051] S26, grow a P-type GaN layer;

[0052] MOCVD growth was employed, with the reaction chamber temperature controlled at 900℃~1050℃ and the pressure at 100Torr~600Torr. NH3 was introduced as the N source, TMGa as the Ga source, and Cp2Mg as the P-type doping source.

[0053] The present invention will be further illustrated below with specific embodiments.

[0054] Example 1

[0055] This embodiment provides a light-emitting diode epitaxial wafer, including a substrate and a composite buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer and a P-type GaN layer sequentially stacked on the substrate.

[0056] The substrate is a Si substrate.

[0057] The composite buffer layer comprises a first buffer layer and a second buffer layer. The first buffer layer consists of sequentially stacked Ga₂O₃ layers and (AlGa)₂O₃ layers. The Ga₂O₃ layer has a thickness of 12 nm, and the (AlGa)₂O₃ layer has a thickness of 120 nm. The Al composition percentage is 0.5%. The second buffer layer consists of periodically alternating first and second GaN layers with a period number of 5. The first GaN layer is a two-dimensional Mg-doped GaN layer with a thickness of 12 nm and a Mg doping concentration of 5 × 10⁻⁶. 16 cm -3 The second GaN layer is a two-dimensional GaN layer with a thickness of 12nm.

[0058] The thickness of the undoped GaN layer is 2 μm.

[0059] The thickness of the N-type GaN layer is 2 μm, and the Si doping concentration is 2.5 × 10⁻⁶. 19 cm -3 .

[0060] The multiple quantum well layer consists of alternating layers of InGaN quantum wells and AlGaN quantum barriers, with a period of 10. The InGaN quantum well layer is 3.5 nm thick with an In content of 0.22%; the AlGaN quantum barrier layer is 9.8 nm thick with an Al content of 0.05%.

[0061] The electron blocking layer is an AlInGaN layer with a thickness of 15 nm, an Al content of 0.1%, and an In content of 0.05%.

[0062] The thickness of the p-type GaN layer is 15 nm, and the Mg doping concentration is 2 × 10⁻⁶. 20 cm -3 .

[0063] The above-mentioned method for fabricating an epitaxial wafer of a light-emitting diode includes the following steps:

[0064] S1. Provide a substrate;

[0065] The substrate used is a Si substrate.

[0066] S2. Sequentially grow a composite buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, and a P-type GaN layer on the substrate; specifically, S2 includes the following steps:

[0067] S21, Growing a composite buffer layer; specifically, S21 includes the following steps:

[0068] S211, Growth of the first buffer layer;

[0069] PLD growth was employed, with the reaction chamber temperature controlled at 620℃ and the pressure at 10. -3 mbar, laser pulse frequency of 2Hz, laser energy density of 2J / cm² 2 The target material is Ga2O3, and a Ga2O3 layer is grown; PLD growth is used, and the reaction chamber temperature is controlled at 800℃ and the pressure at 10℃. -2 mbar, laser pulse frequency of 2Hz, laser energy density of 2J / cm² 2 The target material is Ga2O3 with an Al content of 12% atomic ratio, and an (AlGa)2O3 layer is grown.

[0070] S212, grow the second buffer layer;

[0071] MOCVD was used to grow the first GaN layer, with the reaction chamber temperature controlled at 850℃ and the pressure at 200 Torr. NH3 was introduced as the N source, TMGa as the Ga source, and Cp2Mg as the P-type doping source. The second GaN layer was grown by controlling the reaction chamber temperature at 850℃ and the pressure at 200 Torr, with NH3 as the N source and TMGa as the Ga source. The first and second GaN layers were then stacked and grown periodically.

[0072] S22, grow an undoped GaN layer;

[0073] MOCVD growth was employed, with the reaction chamber temperature controlled at 1100℃ and the pressure at 150 Torr. NH3 was introduced as the N source, and TMGa was introduced as the Ga source.

[0074] S23, grow an N-type GaN layer;

[0075] MOCVD growth was employed, with the reaction chamber temperature controlled at 1120℃ and the pressure at 100 Torr. NH3 was introduced as the N source, TMGa as the Ga source, and SiH4 as the N-type doping source.

[0076] S24, Growth of multiple quantum well layers;

[0077] MOCVD was used to grow InGaN quantum well layers by controlling the reaction chamber temperature at 795℃ and the pressure at 200 Torr, with NH3 as the N source, TMGa as the Ga source, and TMIn as the In source. AlGaN quantum barrier layers were grown by controlling the reaction chamber temperature at 855℃ and the pressure at 200 Torr, with NH3 as the N source, TMGa as the Ga source, and TMAl as the Al source. InGaN quantum well layers and AlGaN quantum barrier layers were then repeatedly stacked and periodically grown.

[0078] S25, growth of electron blocking layer;

[0079] MOCVD growth was employed, with the reaction chamber temperature controlled at 965℃ and the pressure at 200 Torr. NH3 was introduced as the N source, TMGa as the Ga source, TMAl as the Al source, and TMIn as the In source.

[0080] S26, grow a P-type GaN layer;

[0081] MOCVD growth was employed, with the reaction chamber temperature controlled at 985℃ and the pressure at 200 Torr. NH3 was introduced as the N source, TMGa as the Ga source, and Cp2Mg as the P-type doping source.

[0082] Example 2

[0083] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 1 in that the thickness of the Ga2O3 layer is 5 nm and the thickness of the (AlGa)2O3 layer is 50 nm. All other aspects are the same as in Embodiment 1.

[0084] Example 3

[0085] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 2 in that the Al composition ratio of the (AlGa)₂O₃ layer is 0.3, the (AlGa)₂O₃ layer is grown using PLD, and the reaction chamber temperature is controlled at 750°C and the pressure at 10... -3 mbar. Everything else is the same as in Example 2.

[0086] Example 4

[0087] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 3 in that the thickness of the first GaN layer in the second buffer layer is 6 nm, and the Mg doping concentration is 5 × 10⁻⁶. 15 cm -3 The thickness of the second GaN layer is 8 nm. Everything else is the same as in Example 3.

[0088] Comparative Example 1

[0089] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that the composite buffer layer does not include a first buffer layer; correspondingly, the preparation method also excludes the preparation step of the first buffer layer. Everything else is the same as in Example 1.

[0090] Comparative Example 2

[0091] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that the composite buffer layer does not include a second buffer layer; correspondingly, the fabrication method also excludes the step of fabricating the second buffer layer. Everything else is the same as in Example 1.

[0092] Comparative Example 3

[0093] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that the first buffer layer in the composite buffer layer is a (AlGa)₂O₃ layer; correspondingly, in the preparation method, the first buffer layer does not include the preparation step of the Ga₂O₃ layer. All other aspects are the same as in Example 1.

[0094] Comparative Example 4

[0095] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that the second buffer layer in the composite buffer layer is a GaN layer with a thickness of 50 nm. Correspondingly, the preparation method for the second buffer layer is as follows: MOCVD growth is used, controlling the reaction chamber temperature at 850°C and the pressure at 200 Torr, introducing NH3 as the N source and TMGa as the Ga source to grow the GaN layer. All other aspects are the same as in Example 1.

[0096] Performance testing:

[0097] The LED epitaxial wafers obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were fabricated into 10mil × 24mil chips and their performance was tested on the same LED spot tester:

[0098] (1) Photoelectric performance: The luminous efficacy improvement rate of Examples 1 to 4 and Comparative Examples 2 to 4 compared with Comparative Example 1 was calculated by testing at a current of 120mA / 60mA.

[0099] (2) Antistatic capability: The antistatic performance of the chip was tested using an electrostatic meter under the HBM (Human Body Discharge Model) model. The percentage of the chip that could withstand a reverse 6000V static electricity was tested.

[0100] Table 1 Performance test results of LED epitaxial wafers

[0101]

[0102]

[0103] As can be seen from the table, the composite buffer layer structure of the present invention can effectively improve the luminous efficiency and antistatic capability of LEDs.

[0104] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A light-emitting diode epitaxial wafer, characterized in that, The device includes a substrate and a composite buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, and a P-type GaN layer sequentially stacked on the substrate. The composite buffer layer includes a first buffer layer and a second buffer layer. The first buffer layer includes a Ga2O3 layer and a (AlGa)2O3 layer sequentially stacked. The second buffer layer includes a first GaN layer and a second GaN layer stacked alternately in a periodic manner. Both the first GaN layer and the second GaN layer are two-dimensional GaN layers. The thickness of the Ga2O3 layer is 1 nm to 10 nm; The thickness of the (AlGa)2O3 layer is 10nm~100nm.

2. The light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The Al composition of the (AlGa)2O3 layer is 0.1~0.4%.

3. The light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The first GaN layer is a Mg-doped GaN layer with a thickness of 5 nm to 10 nm and a Mg doping concentration of 1 × 10⁻⁶. 15 cm -3 ~1×10 16 cm -3 The thickness of the second GaN layer is 5nm~10nm.

4. The light-emitting diode epitaxial wafer as described in claim 1 or 3, characterized in that, The growth cycle of the second buffer layer is 5 to 8.

5. A method for preparing a light-emitting diode epitaxial wafer, used to prepare a light-emitting diode epitaxial wafer as described in any one of claims 1 to 4, characterized in that, Includes the following steps: A substrate is provided on which a composite buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, and a P-type GaN layer are sequentially grown. The composite buffer layer includes a first buffer layer and a second buffer layer. The first buffer layer includes a Ga2O3 layer and a (AlGa)2O3 layer stacked sequentially. The second buffer layer includes a first GaN layer and a second GaN layer stacked periodically and alternately. Both the first GaN layer and the second GaN layer are two-dimensional GaN layers.

6. The method for fabricating a light-emitting diode epitaxial wafer as described in claim 5, characterized in that, The Ga2O3 layer was grown using a PLD (Plastic Photodeep Deposition Model) at a growth temperature of 600℃~650℃ and a growth pressure of 10. -5 mbar~10 -2 mbar, laser pulse frequency of 2Hz~3Hz, laser energy density of 1.5J / cm² 2 ~2.5J / cm 2 .

7. The method for fabricating a light-emitting diode epitaxial wafer as described in claim 5, characterized in that, The (AlGa)₂O₃ layer was grown using a PLD (Plastic Deposition Model) at a temperature of 610℃ to 800℃ and a growth pressure of 10 kcal / kg. -5 mbar~10 -2 mbar, laser pulse frequency of 2Hz~3Hz, laser energy density of 1.5J / cm² 2 ~2.5J / cm 2 .

8. The method for fabricating a light-emitting diode epitaxial wafer as described in claim 5, characterized in that, The second buffer layer was grown using MOCVD at a temperature of 800℃~1000℃ and a growth pressure of 200Torr~300Torr.

9. A light-emitting diode, characterized in that, The light-emitting diode includes a light-emitting diode epitaxial wafer as described in any one of claims 1 to 4.

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