A light-emitting diode epitaxial wafer and a preparation method thereof

Abstract

The present invention discloses a light-emitting diode epitaxial wafer and a preparation method thereof, relating to the technical field of semiconductor devices. The light-emitting diode epitaxial wafer of the present invention includes a silicon substrate, and a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer which are sequentially stacked on the silicon substrate; the buffer layer includes an oxide layer and a blocking layer which are sequentially stacked on the silicon substrate; the oxide layer includes a three-dimensional Si-graded doped Ta2O5 layer, a three-dimensional Si-graded doped Ga2O3 layer and a two-dimensional (AlGa)2O3 layer which are sequentially stacked; the blocking layer includes a three-dimensional Mg-H doped BAlN layer and a two-dimensional Si3N4 layer which are sequentially stacked. The light-emitting diode epitaxial wafer of the present invention can reduce leakage channels, improve crystal quality, improve the optoelectronic performance of LED devices, and solve the problem of high leakage current existing in GaN-based LEDs on silicon substrates.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and particularly to a light-emitting diode epitaxial wafer and a preparation method thereof. Background Art

[0002] GaN-based light-emitting diodes (LEDs) have the advantages of low voltage, low power consumption, small size, light weight, long life, and high reliability, and are rapidly and widely used in traffic signal lights, mobile phone backlights, outdoor full-color displays, urban landscape lighting, automotive interior and exterior lights, tunnel lights and other fields.

[0003] Common substrates for GaN-based LEDs include sapphire substrates, silicon carbide substrates, and silicon substrates. Silicon substrates are widely used in the manufacture of GaN-based LEDs due to the easy availability of raw materials and relatively low manufacturing costs. However, GaN-based LEDs using silicon substrates as the substrate generally have the problem of high leakage current, which is a major shortcoming of silicon substrate GaN-based LEDs. Currently, mainly by increasing the thickness of the buffer layer on the silicon substrate, to improve the high leakage current problem of silicon substrate GaN-based LEDs. However, this method is difficult to control, with low yield and high cost. Moreover, the not completely insulating silicon substrate will provide electrons to the buffer layer, and the substrate electrons entering the buffer layer increase the leakage current of the buffer layer, resulting in high leakage current of the buffer layer, and thus it is easy to breakdown and cause device damage. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the purpose of the present invention is to provide a light-emitting diode epitaxial wafer, which can reduce the leakage channel, improve the crystal quality, so as to improve the optoelectronic performance of the LED device, and solve the problem of high leakage current existing in silicon substrate GaN-based LEDs.

[0005] Another purpose of the present invention is to provide a preparation method of a light-emitting diode epitaxial wafer for preparing the above-mentioned light-emitting diode epitaxial wafer.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] A light-emitting diode epitaxial wafer, comprising a silicon substrate, and a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer, and a P-type contact layer sequentially stacked on the silicon substrate;

[0008] The buffer layer includes an oxide layer and a barrier layer sequentially stacked on the silicon substrate;

[0009] The oxide layer includes a three-dimensional Si gradient doped Ta 2 O 5 layer, a three-dimensional Si gradient doped Ga 2 O3 layer and two-dimensional (AlGa) 2 O 3 layer;

[0010] The barrier layer includes a three-dimensional Mg-H doped BAlN layer and a two-dimensional Si 3 N 4 layer stacked in sequence.

[0011] Preferably, the total thickness of the oxide layer is 50 nm to 200 nm;

[0012] The three-dimensional Si gradient-doped Ta 2 O 5 layer and the three-dimensional Si gradient-doped Ga 2 O 3 layer have a thickness ratio of 1:1 to 1:2; the three-dimensional Si gradient-doped Ta 2 O 5 layer and the two-dimensional (AlGa) 2 O 3 layer have a thickness ratio of 1:3 to 1:7.

[0013] Preferably, the total thickness of the barrier layer is 100 nm to 240 nm, and the three-dimensional Mg-H doped BAlN layer and the two-dimensional Si 3 N 4 layer have a thickness ratio of 1:1 to 1:10.

[0014] Preferably, the proportion of the Al component in the two-dimensional (AlGa) 2 O 3 layer is 0.3 to 0.6, and the proportion of the Al component increases along the growth direction of the epitaxial wafer.

[0015] Preferably, the doping concentration of Si in the three-dimensional Si gradient-doped Ta 2 O 5 layer is 5×10 15 atoms / cm 3 ~7×10 17 atoms / cm 3 , and along the growth direction of the epitaxial wafer, the doping concentration of Si increases;

[0016] The doping concentration of Si in the three-dimensional Si gradient-doped Ga 2 O 3 layer is 5×10 15 atoms / cm 3 ~7×10 17 atoms / cm 3 , and along the growth direction of the epitaxial wafer, the doping concentration of Si increases.

[0017] Preferably, the proportion of the B component in the three-dimensional Mg-H doped BAlN layer is 0.01 to 0.5, and the proportion of the B component decreases along the growth direction of the epitaxial wafer;

[0018] The doping concentration of Mg in the three-dimensional Mg-H doped BAlN layer is 5×10 17 atoms / cm 3 ~7×10 18 atoms / cm 3 and the doping concentration of H is 1×10 18 atoms / cm 3 ~1×10 19 atoms / cm 3 .

[0019] Correspondingly, the present invention also provides a method for preparing a light-emitting diode epitaxial wafer for preparing the above-mentioned light-emitting diode epitaxial wafer, including the following steps:

[0020] (1) Growing a buffer layer on a silicon substrate;

[0021] (2) Sequentially growing an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer, and a P-type contact layer on the buffer layer;

[0022] The buffer layer includes an oxide layer and a barrier layer sequentially stacked on the silicon substrate;

[0023] The oxide layer includes a three-dimensional Si gradient-doped Ta 2 O 5 layer, a three-dimensional Si gradient-doped Ga 2 O 3 layer, and a two-dimensional (AlGa) 2 O 3 layer;

[0024] The barrier layer includes a three-dimensional Mg-H doped BAlN layer and a two-dimensional Si 3 N 4 layer.

[0025] Preferably, in step (1), the growth temperature of the buffer layer is 800°C to 1100°C, and the growth pressure is 50 torr to 600 torr;

[0026] The three-dimensional Si gradient-doped Ta 2 O 5 layer, the three-dimensional Si gradient-doped Ga 2 O 3 layer, and the three-dimensional Mg-H doped BAlN layer are all three-dimensional structure layers, and the two-dimensional (AlGa)2 O 3 layer and two-dimensional Si 3 N 4 layers are both two-dimensional structure layers; the growth pressure of the three-dimensional structure layer is greater than that of the two-dimensional structure layer.

[0027] Preferably, the growth pressure of the three-dimensional structure layer is 300 torr to 600 torr, and the growth pressure of the two-dimensional structure layer is 50 torr to 300 torr.

[0028] Preferably, in step (2), the growth temperature of the undoped AlGaN layer is 1000 °C to 1300 °C, the growth pressure is 50 torr to 500 torr, and the thickness is 1 μm to 5 μm.

[0029] Implementing the present invention has the following beneficial effects: In this embodiment, an oxide layer and a barrier layer are used to replace the traditional buffer layer. The oxide layer sequentially includes a three-dimensional Si gradient-doped Ta 2 O 5 layer, a three-dimensional Si gradient-doped Ga 2 O 3 layer, and a two-dimensional (AlGa) 2 O 3 layer. Based on the oxide layer with the above special structure, the lattice mismatch and thermal mismatch between the silicon substrate and the epitaxial layer can be gradually reduced, the generation of defects can be reduced, and thus the leakage channels of electrons can be effectively reduced. At the same time, it can effectively compensate for the huge tensile stress caused by the different thermal expansion coefficients of the silicon substrate and the GaN film layer during the subsequent cooling process, and reduce the generation of cracks. In addition, the three-dimensional Si gradient-doped Ga 2 O 3 layer can reduce the generation of screw dislocations and change their extension directions while ensuring the crystal quality of the two-dimensional (AlGa) 2 O 3 layer, thereby reducing dislocations; the two-dimensional (AlGa) 2 O 3 layer has a relatively high bandgap, between 5 eV and 5.3 eV. Ensuring a relatively high bandgap can effectively prevent the mobility of electrons, thereby reducing the generation of leakage channels and improving the optoelectronic performance. The barrier layer in this embodiment includes a three-dimensional Mg-H doped BAlN layer and a two-dimensional Si 3 N 4 layer stacked in sequence, so that the three-dimensional structure layer and the two-dimensional structure layer in the entire buffer layer grow alternately, which can effectively block the extension of dislocation lines and improve the crystal quality of the epitaxial layer. In addition, the two-dimensional Si 3 N 4 layer is the barrier for finally blocking the extension of dislocations, which can further improve the crystal quality of the epitaxial wafer. Description of the Drawings

[0030] Figure 1 It is a schematic structural diagram of a light-emitting diode epitaxial wafer in Embodiment 1 of the present invention;

[0031] Among them, the silicon substrate 1, the buffer layer 2, the undoped AlGaN layer 3, the N-type AlGaN layer 4, the multi-quantum well layer 5, the electron blocking layer 6, the P-type AlGaN layer 7, the P-type contact layer 8, the oxide layer 21, the blocking layer 22, the three-dimensional Si graded doped Ta 2 O 5 layer 211, the three-dimensional Si graded doped Ga 2 O 3 layer 212, the two-dimensional (AlGa) 2 O 3 layer 213, the three-dimensional Mg-H doped BAlN layer 221, the two-dimensional Si 3 N 4 layer 222. Detailed implementation manners

[0032] 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 the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0033] For those technologies or conditions not specified in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. For raw materials not indicating the manufacturer, they are all conventional products that can be obtained through commercial procurement.

[0034] Refer to Figure 1 , a light-emitting diode epitaxial wafer, comprising a silicon substrate 1, and a buffer layer 2, an undoped AlGaN layer 3, an N-type AlGaN layer 4, a multi-quantum well layer 5, an electron blocking layer 6, a P-type AlGaN layer 7, and a P-type contact layer 8 sequentially stacked on the silicon substrate 1;

[0035] The buffer layer 2 includes an oxide layer 21 and a blocking layer 22 sequentially stacked on the silicon substrate 1;

[0036] The oxide layer 21 includes a three-dimensional Si graded doped Ta 2 O 5 layer 211, a three-dimensional Si graded doped Ga 2 O 3 layer 212, and a two-dimensional (AlGa) 2 O 3 layer 213;

[0037] The blocking layer 22 includes a three-dimensional Mg-H doped BAlN layer 221 and a two-dimensional Si3 N 4 Layer 222.

[0038] It should be noted that in this embodiment, the oxide layer 21 and the barrier layer 22 are used to replace the traditional buffer layer. The oxide layer 21 sequentially includes a three-dimensional Si gradient-doped Ta 2 O 5 layer 211, a three-dimensional Si gradient-doped Ga 2 O 3 layer 212, and a two-dimensional (AlGa) 2 O 3 layer 213. Based on the oxide layer 21 with the above special structure, the lattice mismatch and thermal mismatch between the silicon substrate 1 and the epitaxial layer (i.e., the combined layer composed of the buffer layer 2, the undoped AlGaN layer 3, the N-type AlGaN layer 4, the multi-quantum well layer 5, the electron blocking layer 6, the P-type AlGaN layer 7, and the P-type contact layer 8) can be gradually reduced, the generation of defects can be reduced, and thus the leakage channels of electrons can be effectively reduced. At the same time, the huge tensile stress caused by the different thermal expansion coefficients of the silicon substrate and the GaN film layer during the later cooling process can be effectively compensated, and the generation of cracks can be reduced. In addition, the three-dimensional Si gradient-doped Ga 2 O 3 layer 212 can reduce the generation of screw dislocations and change their extension directions while ensuring the crystal quality of the two-dimensional (AlGa) 2 O 3 layer 213, thereby reducing dislocations; the two-dimensional (AlGa) 2 O 3 layer 213 has a relatively high bandgap, between 5 eV and 5.3 eV. Ensuring a relatively high bandgap can effectively prevent electron migration, reduce the electron mobility, and thus reduce the generation of leakage channels and improve the optoelectronic performance. The barrier layer 22 includes a three-dimensional Mg-H doped BAlN layer 221 and a two-dimensional Si 3 N 4 layer 222 stacked in sequence, enabling the three-dimensional structure layers and the two-dimensional structure layers in the entire buffer layer 2 to grow alternately, which can effectively block the extension of dislocation lines and improve the crystal quality of the epitaxial layer. Among them, the two-dimensional Si 3 N 4 layer 222 can change the upward extension direction of the dislocation lines, cause two or more dislocation lines to intersect and annihilate, playing a blocking role. Therefore, the two-dimensional Si 3 N 4 layer 222 is the last barrier to block the extension of dislocation lines, which can further improve the crystal quality of the epitaxial layer. In addition, between the two-dimensional (AlGa) 2 O 3 layer 213 and the two-dimensional Si 3 N 4A three-dimensional Mg-H doped BAlN layer 221 is provided between the layers 222. The holes generated in the three-dimensional Mg-H doped BAlN layer 221 can neutralize a part of the leakage electrons, promote the lateral expansion of the current, and reduce the migration speed of the electrons, thereby further reducing the leakage current and improving the optoelectronic performance of the light-emitting diode.

[0039] Furthermore, by using the combination of the oxide layer 21 and the barrier layer 22 to replace the traditional buffer layer, the leakage channels can be reduced, the crystal quality can be improved, so as to improve the optoelectronic performance of the device, and the problem of high leakage current existing in the GaN-based LED using a silicon substrate as the substrate is solved.

[0040] Specifically, in a preferred embodiment of the present invention, the silicon substrate 1 is a Si(111) substrate.

[0041] It should be noted that the substrate used for the light-emitting diode epitaxial wafer is not limited to a silicon substrate, and other substrates can also be used, such as a sapphire substrate, a silicon carbide substrate (such as a SiC(0001) substrate).

[0042] Further description, the total thickness of the oxide layer 21 is 50 nm to 200 nm;

[0043] The three-dimensional Si gradient doped Ta 2 O 5 layer and the three-dimensional Si gradient doped Ga 2 O 3 layer have a thickness ratio of 1:1 to 1:2; the three-dimensional Si gradient doped Ta 2 O 5 layer and the two-dimensional (AlGa) 2 O 3 layer have a thickness ratio of 1:3 to 1:7. The thickness ratio of the three-dimensional Si gradient doped Ta 2 O 5 layer 211, the three-dimensional Si gradient doped Ga 2 O 3 layer 212 and the two-dimensional (AlGa) 2 O 3 layer 213 within the above range can reduce the lattice matching and thermal matching between the substrate and the epitaxial layer, help reduce the defects generated due to lattice mismatch and thermal mismatch, and since the two-dimensional (AlGa) 2 O 3 layer 213 has a relatively thick thickness, it can better block the migration of electrons, thereby reducing the generation of leakage channels, and further improving the light efficiency and reliability of the light-emitting diode.

[0044] The three-dimensional Si gradient doped Ta 2 O 5 layer 211, the three-dimensional Si gradient doped Ga2 O 3 Layer 212 and two-dimensional (AlGa) 2 O 3 The thickness ratio of layer 213 is exemplary 1:1:3, 1:1:4, 1:1:5, 1:1:6, 1:1:7, 1:1.5:6, 1:2:7, but not limited thereto.

[0045] More preferably, in this technical solution, three-dimensional Si is gradually doped with Ta 2 O 5 Layer 211, three-dimensional Si is gradually doped with Ga 2 O 3 Layer 212 and two-dimensional (AlGa) 2 O 3 The thickness ratio of layer 213 is 1:1:5.

[0046] Further illustration, the thickness of the barrier layer 22 is 100 nm to 240 nm; the thickness ratio of the three-dimensional Mg-H doped BAlN layer 221 and the two-dimensional Si 3 N 4 Layer 222 is 1:1 to 1:10, exemplary 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, but not limited thereto.

[0047] More preferably, the thickness of the two-dimensional Si 3 N 4 Layer 222 is greater than the thickness of the three-dimensional Mg-H doped BAlN layer 221. The two-dimensional Si 3 N 4 The material of layer 222 is Si 3 N 4 , Si 3 N 4 has strong masking ability and high dielectric properties. Taking the two-dimensional Si 3 N 4 Layer 222 as the outermost layer of the buffer layer 2 can effectively block the extension of dislocation lines, and when the thickness of the two-dimensional Si 3 N 4 Layer 222 is relatively thick, it can play a better blocking role, effectively improve the crystal quality of the epitaxial layer, and then improve the optoelectronic properties. Moreover, based on Si 3 N 4 has high dielectric strength and masking ability, so the light-emitting diode can obtain a higher breakdown voltage, enabling the LED to work normally at a higher voltage without being damaged, enhancing the voltage withstand capacity of the LED, enabling it to emit light stably under various voltage conditions, and improving the reliability and stability of its application.

[0048] Further illustration, the two-dimensional (AlGa)2 O 3 The proportion of the Al component in the layer 213 is 0.3 - 0.6, and the proportion of the Al component increases along the growth direction of the epitaxial wafer. Based on the above improvements, the two-dimensional (AlGa) 2 O 3 The barrier height of the layer 213 continuously rises, which can gradually reduce the upward migration of electrons in the bottom layer, thereby reducing the generation of leakage channels.

[0049] For further illustration, the three-dimensional Si graded-doped Ta 2 O 5 The doping concentration of Si in the layer 211 is 5×10 15 atoms / cm 3 ~7×10 17 atoms / cm 3 , and along the growth direction of the epitaxial wafer, the doping concentration of Si increases;

[0050] The three-dimensional Si graded-doped Ga 2 O 3 The doping concentration of Si in the layer 212 is 5×10 15 atoms / cm 3 ~7×10 17 atoms / cm 3 , and along the growth direction of the epitaxial wafer, the doping concentration of Si increases;

[0051] Based on the three-dimensional Si graded-doped Ta 2 O 5 layer 211 and the three-dimensional Si graded-doped Ga 2 O 3 layer 212, the doping concentration of Si is 5×10 15 atoms / cm 3 ~7×10 17 atoms / cm 3 , and along the growth direction of the epitaxial wafer, the doping concentration of Si increases. This can gradually reduce the lattice mismatch and thermal mismatch between the substrate and the epitaxial layer, reduce the generation of defects, thereby effectively reducing the leakage channels of electrons. At the same time, it can effectively compensate for the huge tensile stress caused by the different thermal expansion coefficients of the silicon substrate and the GaN film layer during the later cooling process, reducing the generation of cracks. The three-dimensional Si graded-doped Ga 2 O 3 layer 212, while ensuring the crystal quality of the two-dimensional (AlGa) 2 O 3 layer 213, Si doping can reduce the generation of screw dislocations and change their extension directions, thereby reducing dislocations.

[0052] Further explanation, the proportion of B component in the three-dimensional Mg-H doped BAlN layer 221 is 0.01-0.5, and the proportion of B component decreases along the growth direction of the epitaxial wafer;

[0053] The doping concentration of Mg in the three-dimensional Mg-H doped BAlN layer 221 is 5×10 17 atoms / cm 3 ~7×10 18 atoms / cm 3 and the doping concentration of H is 1×10 18 atoms / cm 3 ~1×10 19 atoms / cm 3 。

[0054] It is worth noting that the doping efficiency of Mg is related to the H doping concentration. In this embodiment, appropriate H doping is carried out in the three-dimensional Mg-H doped BAlN layer 221, which can improve the effective doping of Mg, effectively increase the hole concentration in the three-dimensional Mg-H doped BAlN layer 221. The holes generated in the three-dimensional Mg-H doped BAlN layer 221 can neutralize a part of the leakage electrons, promote the lateral expansion of the current, and reduce the migration speed of electrons, thereby further reducing the leakage current and improving the optoelectronic performance.

[0055] A method for preparing a light-emitting diode epitaxial wafer for preparing the above-mentioned light-emitting diode epitaxial wafer, comprising the following steps:

[0056] (1) Growing the buffer layer 2 on the silicon substrate 1;

[0057] (2) Sequentially growing the undoped AlGaN layer 3, the N-type AlGaN layer 4, the multi-quantum well layer 5, the electron blocking layer 6, the P-type AlGaN layer 7 and the P-type contact layer 8 on the buffer layer 2.

[0058] Further explanation, in step (1), the growth temperature of the buffer layer 2 is 800°C-1100°C, and the growth pressure is 50 torr-600 torr;

[0059] The three-dimensional Si gradient-doped Ta 2 O 5 layer 211, the three-dimensional Si gradient-doped Ga 2 O 3 layer 212 and the three-dimensional Mg-H doped BAlN layer 221 are all three-dimensional structure layers, and the two-dimensional (AlGa) 2 O 3 layer 213 and two-dimensional Si 3 N 4The layer 222 is a two-dimensional structure layer; the growth pressure of the three-dimensional structure layer is greater than that of the two-dimensional structure layer. By controlling the growth pressure of the three-dimensional structure layer to be greater than that of the two-dimensional structure layer, the generation of dislocation lines can be reduced, the overall quality of the epitaxial layer can be improved, and thus the light-emitting efficiency of the LED can be improved.

[0060] More preferably, in step (1), the growth pressure of the three-dimensional structure layer is 300 torr to 600 torr, and the growth pressure of the two-dimensional structure layer is 50 torr to 300 torr.

[0061] Preferably, the growth atmosphere of the buffer layer 2 is N 2 -H 2 -NH 3 mixed gas, and the N 2 -H 2 -NH 3 In the mixed gas, the volume ratio of N 2 , H 2 and NH 3 is 1:1:1 to 1:10:10.

[0062] Further explanation, in step (2), the growth temperature of the undoped AlGaN layer 3 is 1000 °C to 1300 °C, the growth pressure is 50 torr to 500 torr, and the thickness is 1 μm to 5 μm. The growth temperature of the undoped AlGaN layer is relatively high and the pressure is relatively low, so the crystal quality of the prepared GaN is relatively good. At the same time, as the thickness of the AlGaN increases, the compressive stress will be released through stacking faults, the line defects will be reduced, the crystal quality will be improved, and the reverse leakage current will be reduced.

[0063] Specifically, the undoped AlGaN layer 3 is deposited on the buffer layer 2 by metal organic chemical vapor deposition (MOCVD), the growth temperature is 1000 °C to 1300 °C, the growth pressure is 50 torr to 500 torr, and the thickness is 1 μm to 5 μm.

[0064] The growth temperature of the undoped AlGaN layer 3 is exemplarily 1000 °C, 1100 °C, 1200 °C, 1300 °C, but not limited thereto. The growth pressure of the undoped AlGaN layer 3 is exemplarily 50 torr, 100 torr, 150 torr, 200 torr, 250 torr, 300 torr, 350 torr, 400 torr, 450 torr, 500 torr, but not limited thereto. The thickness of the undoped AlGaN layer 3 is exemplarily 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, but not limited thereto.

[0065] In an alternative embodiment of the present invention, the growth temperature of the undoped AlGaN layer 3 is 1200 °C, the growth pressure is 100 torr, and the growth thickness is 2 μm to 3 μm.

[0066] Further, an N-type AlGaN layer 4 is deposited on the undoped AlGaN layer 3. The thickness of the N-type AlGaN layer 4 is 1 μm to 5 μm, the growth temperature is 1000 °C to 1300 °C, the growth pressure is 50 torr to 500 torr, and the Si doping concentration is 1×10 19 atoms / cm 3 ~5×10 20 atoms / cm 3 . First, the N-type AlGaN layer can provide sufficient electrons for the ultraviolet LED to recombine with holes. Second, the resistivity of the N-type AlGaN layer is higher than that of the transparent electrode on the P-type GaN layer. Therefore, sufficient Si doping can effectively reduce the resistivity of the N-type AlGaN layer. Finally, the sufficient thickness of the N-type AlGaN layer can effectively release stress and improve the luminous efficiency of the light-emitting diode.

[0067] More preferably, the growth temperature of the N-type AlGaN layer 4 is 1150 °C to 1250 °C, the growth pressure is 80 torr to 150 torr, the growth thickness is 2 μm to 3 μm, and the Si doping concentration is 2×10 19 atoms / cm 3 ~5×10 19 atoms / cm 3 .

[0068] In an alternative embodiment of the present invention, the growth temperature of the N-type AlGaN layer 4 is 1200 °C, the growth pressure is 100 torr, the growth thickness is 3 μm, and the Si doping concentration is 2.5×10 19 atoms / cm 3 .

[0069] Further, a multi-quantum well layer 5 is deposited on the N-type AlGaN layer 4. The multi-quantum well layer 5 is preferably a combination of periodically alternating stacked Al x Ga 1-x N quantum well layers and Al y Ga 1-y N quantum barrier layers, and the number of stacking periods is 6 to 12. Among them, the thickness of the Al x Ga 1-x N quantum well layer is 2 nm to 5 nm, the growth temperature is 950 °C to 1050 °C, the growth pressure is 50 torr to 300 torr, and the Al component x is 0.2 to 0.6; Al y Ga 1-yThe thickness of the N quantum barrier layer is 5 nm to 15 nm, the Al composition y is 0.4 to 0.8, the growth temperature is 850 °C to 950 °C, and the growth pressure is 50 torr to 300 torr. The multi-quantum well layer is the region where electrons and holes recombine. A reasonable structural design can significantly increase the overlap degree of the electron and hole wave functions, thereby improving the light-emitting efficiency of the LED device.

[0070] More preferably, the number of stacking periods of the multi-quantum well layer 5 is 8 to 12. Among them, Al x Ga 1-x The thickness of the N quantum well layer is 3 nm to 4 nm, the growth temperature is 980 °C to 1020 °C, the growth pressure is 150 torr to 250 torr, and the Al composition x is 0.4 to 0.5; Al y Ga 1-y The thickness of the N quantum barrier layer is 10 nm to 13 nm, the Al composition y is 0.45 to 0.6, the growth temperature is 880 °C to 910 °C, and the growth pressure is 150 torr to 250 torr.

[0071] In an alternative embodiment of the present invention, the number of stacking periods of the multi-quantum well layer 5 is 9. Among them, Al x Ga 1-x The thickness of the N quantum well layer is 3.5 nm, the Al composition x is 0.45, the growth temperature is 1000 °C, and the growth pressure is 200 torr; Al y Ga 1-y The thickness of the N quantum barrier layer is 11 nm, the Al composition y is 0.55, the growth temperature is 900 °C, and the growth pressure is 200 torr.

[0072] Further illustration, an electron blocking layer 6 is deposited on the multi-quantum well layer 5. The electron blocking layer 6 is preferably an AlGaN electron blocking layer, where the Al composition is 0.4 to 0.8, the thickness is 10 nm to 50 nm, the growth temperature is 1000 °C to 1100 °C, and the pressure is 100 torr to 300 torr. It can not only effectively limit the electron overflow, but also reduce the blocking of holes, improve the injection efficiency of holes into the quantum well, reduce the carrier Auger recombination, and improve the light-emitting efficiency of the light-emitting diode.

[0073] More preferably, the thickness of the electron blocking layer 6 is 25 nm to 40 nm, the Al composition is 0.5 to 0.7, the growth temperature is 1020 °C to 1070 °C, and the growth pressure is 150 torr to 250 torr.

[0074] In an alternative embodiment of the present invention, the thickness of the electron blocking layer 6 is 30 nm, the Al composition is 0.65, the growth temperature is 1050 °C, and the growth pressure is 200 torr.

[0075] Further description: A P-type AlGaN layer 7 is deposited on the electron blocking layer 6. The thickness of the P-type AlGaN layer 7 is 100 nm to 200 nm, and the Mg doping concentration is 1×10 19 atoms / cm 3 ~5×10 20 atoms / cm 3 , the growth temperature is 1000 °C to 1100 °C, and the growth pressure is 100 torr to 600 torr. If the Mg doping concentration is too high, the crystal quality will be damaged, while a lower doping concentration will affect the hole concentration. At the same time, the P-type AlGaN layer 7 can effectively fill the epitaxial layer to obtain a smooth-surface ultraviolet LED epitaxial wafer.

[0076] Preferably, the thickness of the P-type AlGaN layer 7 is 130 nm to 180 nm, the growth temperature is 1020 °C to 1070 °C, the growth pressure is 150 torr to 250 torr, and the Mg doping concentration is 2×10 19 atoms / cm 3 ~9×10 19 atoms / cm 3 .

[0077] In an alternative embodiment of the present invention, the thickness of the P-type AlGaN layer 7 is 150 nm, the growth temperature is 1050 °C, the growth pressure is 200 torr, and the Mg doping concentration is 5×10 19 atoms / cm 3 .

[0078] Further description: A P-type contact layer 8 is deposited on the P-type AlGaN layer 7. The thickness of the P-type contact layer 8 is 10 nm to 50 nm, and the Mg doping concentration is 5×10 19 atoms / cm 3 ~5×10 20 atoms / cm 3 , the growth temperature is 1000 °C to 1100 °C, and the growth pressure is 100 torr to 600 torr. A P-type contact layer with a higher doping concentration can further reduce the contact resistance.

[0079] Preferably, the thickness of the P-type contact layer 8 is 15 nm to 30 nm, the Mg doping concentration is 9×10 19 atoms / cm 3 ~3×10 20 atoms / cm 3 , the growth temperature is 1030 °C to 1080 °C, and the growth pressure is 150 torr to 250 torr.

[0080] In an alternative embodiment of the present invention, the thickness of the P-type contact layer is 20 nm, the growth temperature is 1050 °C, the growth pressure is 200 torr, and the Mg doping concentration is 1×10 20 atoms / cm 3 ,

[0081] The technical solution of the present invention will be further described below through examples and comparative examples.

[0082] Example 1

[0083] The light-emitting diode epitaxial wafer of this example includes a silicon substrate 1, and a buffer layer 2, an undoped AlGaN layer 3, an N-type AlGaN layer 4, a multi-quantum well layer 5, an electron blocking layer 6, a P-type AlGaN layer 7, and a P-type contact layer 8 that are sequentially stacked on the silicon substrate 1; the buffer layer 2 includes an oxide layer 21 and a barrier layer 22 that are sequentially stacked on the silicon substrate 1; the oxide layer 21 includes a three-dimensional Si graded doped Ta 2 O 5 layer 211, a three-dimensional Si graded doped Ga 2 O 3 layer 212, and a two-dimensional (AlGa) 2 O 3 layer 213; the barrier layer 22 includes a three-dimensional Mg-H doped BAlN layer 221 and a two-dimensional Si 3 N 4 layer 222 (as Figure 1 shown).

[0084] Among them, the total thickness of the oxide layer 21 is 140 nm, and the thickness ratio of the three-dimensional Si graded doped Ta 2 O 5 layer 211, the three-dimensional Si graded doped Ga 2 O 3 layer 212, and the two-dimensional (AlGa) 2 O 3 layer 213 is 1:1:3; the total thickness of the barrier layer 22 is 175 nm, and the thickness ratio of the three-dimensional Mg-H doped BAlN layer 221 and the two-dimensional Si 3 N 4 layer 222 is 1:1.

[0085] In the three-dimensional Si graded doped Ta 2 O 5 layer 211, the doping concentration of Si increases linearly from 5×10 15 atoms / cm 3 to 1×10 16 atoms / cm 3 along the growth direction of the epitaxial wafer;

[0086] Three-dimensional Si graded doped Ga 2 O 3 In layer 212, the doping concentration of Si increases linearly from 5×10 15 atoms / cm 3 to 9×10 15 atoms / cm 3 along the growth direction of the epitaxial wafer;

[0087] Two-dimensional (AlGa) 2 O 3 In layer 213, the proportion of the Al component increases linearly from 0.3 to 0.4 along the growth direction of the epitaxial wafer;

[0088] In the three-dimensional Mg-H doped BAlN layer 221, the proportion of the B component decreases linearly from 0.15 to 0.1 along the growth direction of the epitaxial wafer; the doping concentration of Mg in the three-dimensional Mg-H doped BAlN layer 221 is 6×10 17 atoms / cm 3 , and the doping concentration of H is 1×10 18 atoms / cm 3 .

[0089] The method for preparing the light-emitting diode epitaxial wafer in this embodiment includes the following steps:

[0090] (1) Provide a silicon substrate 1, and the silicon substrate 1 is a Si(111) substrate;

[0091] (2) Grow a buffer layer 2 on the silicon substrate 1; the growth temperature of the buffer layer 2 is 950°C, and the growth pressures of the three-dimensional Si graded doped Ta 2 O 5 layer 211, the three-dimensional Si graded doped Ga 2 O 3 layer 212, and the three-dimensional Mg-H doped BAlN layer 221 are all 500 torr, and the growth pressures of the two-dimensional (AlGa) 2 O 3 layer 213 and the two-dimensional Si 3 N 4 layer are all 150 torr;

[0092] (3) Sequentially grow an undoped AlGaN layer 3, an N-type AlGaN layer 4, a multi-quantum well layer 5, an electron blocking layer 6, a P-type AlGaN layer 7, and a P-type contact layer 8 on the buffer layer 2.

[0093] Example 2

[0094] The structural composition and preparation method of the light-emitting diode epitaxial wafer in this embodiment are basically the same as those in Embodiment 1, except that: in the three-dimensional Mg-H doped BAlN layer of this embodiment, the proportion of B component is 0.05 - 0.35, and the proportion of B component linearly decreases from 0.35 to 0.05 along the growth direction of the epitaxial wafer; the doping concentration of Mg in the three-dimensional Mg-H doped BAlN layer is 3×10 18 atoms / cm 3 and the doping concentration of H is 9×10 18 atoms / cm 3 .

[0095] Embodiment 3

[0096] The structural composition and preparation method of the light-emitting diode epitaxial wafer in this embodiment are basically the same as those in Embodiment 2, except that: the total thickness of the oxide layer 21 in this embodiment is 140 nm, and the thickness ratio of the three-dimensional Si gradually doped Ta 2 O 5 layer 211, the three-dimensional Si gradually doped Ga 2 O 3 layer 212 and the two-dimensional (AlGa) 2 O 3 layer 213 is 1:1:5; the thickness of the barrier layer 22 is 175 nm, and the thickness ratio of the three-dimensional Mg-H doped BAlN layer 221 and the two-dimensional Si 3 N 4 layer 222 is 1:6.

[0097] Embodiment 4

[0098] The structural composition and preparation method of the light-emitting diode epitaxial wafer in this embodiment are basically the same as those in Embodiment 3, except that: in the two-dimensional (AlGa) 2 O 3 layer 213 of this embodiment, the proportion of Al component is 0.35 - 0.55, and the proportion of Al component linearly increases from 0.35 to 0.55 along the growth direction of the epitaxial wafer.

[0099] Embodiment 5

[0100] The structural composition and preparation method of the light-emitting diode epitaxial wafer in this embodiment are basically the same as those in Embodiment 4, except that: the doping concentration of Si in the three-dimensional Si gradually doped Ta 2 O 5 layer 211 of this embodiment is 7×10 15 atoms / cm 3 ~1×10 17 atoms / cm 3 , and along the growth direction of the epitaxial wafer, the doping concentration of Si is 7×10 15 atoms / cm3 Linearly increase to 1×10 17 atoms / cm 3 ;

[0101] Three-dimensional Si graded-doped Ga 2 O 3 The doping concentration of Si in layer 212 is 5×10 15 atoms / cm 3 ~9×10 16 atoms / cm 3 and along the growth direction of the epitaxial wafer, the doping concentration of Si increases linearly from 5×10 15 atoms / cm 3 to 9×10 16 atoms / cm 3 .

[0102] Comparative Example 1

[0103] The structural composition and preparation method of the light-emitting diode epitaxial wafer in this comparative example are basically the same as those in Example 1, except that: the buffer layer in this comparative example is a traditional buffer layer. Specifically, the buffer layer is an AlN buffer layer.

[0104] Comparative Example 2

[0105] The structural composition and preparation method of the light-emitting diode epitaxial wafer in this comparative example are basically the same as those in Example 1, except that: in this comparative example, the doping concentration of Si in the three-dimensional Si graded-doped Ta 2 O 5 layer is 7×10 15 atoms / cm 3 , and the Si doping concentration remains constant; the doping concentration of Si in the three-dimensional Si graded-doped Ga 2 O 3 layer is 5×10 15 atoms / cm 3 , and the Si doping concentration remains constant.

[0106] Comparative Example 3

[0107] The structural composition and preparation method of the light-emitting diode epitaxial wafer in this comparative example are basically the same as those in Example 1, except that: the growth pressure of the entire buffer layer in this comparative example is 100 torr, that is, the three-dimensional Si graded-doped Ta 2 O 5 layer, the three-dimensional Si graded-doped Ga 2 O 3 layer, the three-dimensional Mg-H doped BAlN layer, the two-dimensional (AlGa) 2 O 3 layer and the two-dimensional Si 3 N4 The growth pressure of each layer is 100 torr.

[0108] Comparative Example 4

[0109] The structural composition and preparation method of the light-emitting diode epitaxial wafer in this comparative example are basically the same as those in Example 1, except that: in the three-dimensional Mg-H doped BAlN layer of this comparative example, the proportion of the B component is 0.1, and the proportion of the B component in the three-dimensional Mg-H doped BAlN layer remains constant; at the same time, only Mg is doped in the three-dimensional Mg-H doped BAlN layer of this comparative example, without doping H, and the Mg doping concentration is 5×10 17 atoms / cm 3 .

[0110] Performance test:

[0111] The light-emitting diode epitaxial wafers obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were prepared into 20 mil×24 mil chips under the same chip process conditions, and 300 LED chips were respectively selected, and their performance was tested on the same LED tester:

[0112] (1) Photoelectric performance: The luminous efficiency was tested under a working current of 120 mA, and the light efficiency improvement rate of Examples 1 to 5 and Comparative Examples 2 to 4 compared with Comparative Example 1 was calculated.

[0113] (2) Antistatic ability: Under the HBM (human body discharge model) model, the antistatic performance of the chips was tested using an electrostatic instrument, the passing ratio of the chips that could withstand a reverse static electricity of 4000 V was tested, and the passing ratio improvement rate (i.e., ESD improvement rate) of Examples 1 to 5 and Comparative Examples 2 to 4 compared with Comparative Example 1 was calculated.

[0114] Specifically, the performance test results are shown in Table 1 below.

[0115] Table 1 Performance test results

[0116]

[0117] It can be seen from the above experimental data that using the light-emitting diode epitaxial wafers of Examples 1 to 5 to prepare LED chips can effectively reduce the leakage channels, improve the crystal quality, and thus effectively improve the photoelectric performance of the LED chips.

[0118] The above-disclosed is only a preferred embodiment of the present invention. Of course, it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A light emitting diode epitaxial wafer, characterized in that: It comprises a silicon substrate, and a buffer layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer which are sequentially stacked on the silicon substrate; The buffer layer includes an oxide layer and a barrier layer sequentially stacked on the silicon substrate; The oxide layer comprises a three-dimensional Si gradient doped Ta2O5 layer, a three-dimensional Si gradient doped Ga2O3 layer and a two-dimensional (AlGa)2O3 layer stacked in sequence; The barrier layer comprises a three-dimensional Mg-H doped BAlN layer and a two-dimensional Si3N4 layer stacked in sequence; The thickness ratio of the three-dimensional Si gradient doped Ta2O5 layer to the three-dimensional Si gradient doped Ga2O3 layer is 1:1~1:2; the thickness ratio of the three-dimensional Si gradient doped Ta2O5 layer to the two-dimensional (AlGa)2O3 layer is 1:3~1:

7.

2. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The total thickness of the oxide layer is 50nm~200nm.

3. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The total thickness of the barrier layer is 100nm~240nm, and the thickness ratio of the three-dimensional Mg-H doped BAlN layer to the two-dimensional Si3N4 layer is 1:1~1:

10.

4. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The proportion of Al component in the two-dimensional (AlGa)2O3 layer is 0.3-0.6, and the proportion of Al component increases along the growth direction of the epitaxial wafer.

5. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The doping concentration of Si in the three-dimensional Si gradient doped Ta2O5 layer is 5×10 15 atoms / cm 3 ~7×10 17 atoms / cm 3 , and along the growth direction of the epitaxial wafer, the doping concentration of Si increases; The doping concentration of Si in the three-dimensional Si-gradient doped Ga2O3 layer is 5×10 15 atoms / cm 3 ~7×10 17 atoms / cm 3 , and the doping concentration of Si increases along the growth direction of the epitaxial wafer.

6. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The proportion of B component in the three-dimensional Mg-H doped BAlN layer is 0.01-0.5, and the proportion of B component decreases along the growth direction of the epitaxial wafer; The Mg doping concentration in the three-dimensional Mg-H doped BAlN layer is 5×10 17 atoms / cm 3 ~7×10 18 atoms / cm 3 , the doping concentration of H is 1×10 18 atoms / cm 3 ~1×10 19 atoms / cm 3 .

7. A method for preparing a light emitting diode epitaxial wafer, characterized in that: The method for preparing the light emitting diode epitaxial wafer according to any one of claims 1 to 6 comprises the following steps: (1) Growing a buffer layer on a silicon substrate; (2) sequentially growing an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer on the buffer layer; The buffer layer includes an oxide layer and a barrier layer sequentially stacked on the silicon substrate; The oxide layer comprises a three-dimensional Si gradient doped Ta2O5 layer, a three-dimensional Si gradient doped Ga2O3 layer and a two-dimensional (AlGa)2O3 layer stacked in sequence; The barrier layer includes a three-dimensional Mg-H doped BAlN layer and a two-dimensional Si3N4 layer stacked in sequence.

8. The method for preparing a light emitting diode epitaxial wafer according to claim 7, characterized in that: In step (1), the growth temperature of the buffer layer is 800° C. to 1100° C., and the growth pressure is 50 torr to 600 torr; The three-dimensional Si gradient-doped Ta2O5 layer, the three-dimensional Si gradient-doped Ga2O3 layer and the three-dimensional Mg-H doped BAlN layer are all three-dimensional structural layers, and the two-dimensional (AlGa)2O3 layer and the two-dimensional Si3N4 layer are both two-dimensional structural layers; the growth pressure of the three-dimensional structural layer is greater than the growth pressure of the two-dimensional structural layer.

9. The method for preparing a light emitting diode epitaxial wafer according to claim 8, characterized in that: The growth pressure of the three-dimensional structure layer is 300 torr to 600 torr, and the growth pressure of the two-dimensional structure layer is 50 torr to 300 torr.

10. The method for preparing a light emitting diode epitaxial wafer according to claim 7, characterized in that: In step (2), the growth temperature of the non-doped AlGaN layer is 1000° C. to 1300° C., the growth pressure is 50 torr to 500 torr, and the thickness is 1 μm to 5 μm.

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