Light emitting diode epitaxial wafer and preparation method thereof

Abstract

The invention discloses a light-emitting diode epitaxial wafer and a preparation method thereof, and relates to the technical field of semiconductor devices. The light-emitting diode epitaxial wafer 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 barrier layer, a P-type AlGaN layer and a P-type contact layer which are sequentially stacked on the silicon substrate, the buffer layer comprises an oxide layer and a barrier layer which are 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 which are stacked in sequence; the barrier layer comprises a three-dimensional Mg-H doped BAN layer and a two-dimensional Si3N4 layer which are stacked in sequence. According to the light-emitting diode epitaxial wafer, electric leakage channels can be reduced, the crystal quality is improved, the photoelectric property of an LED device is improved, and the problem of high leakage current of a silicon substrate GaN-based LED is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular 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. They are rapidly being widely used in traffic 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 because of their easy availability of raw materials and relatively low manufacturing costs. However, GaN-based LEDs using silicon substrates as substrates generally have the problem of high leakage current, which is a major shortcoming of GaN-based LEDs with silicon substrates. Currently, the problem of high leakage current of GaN-based LEDs with silicon substrates is mainly improved by increasing the thickness of the buffer layer on the silicon substrate. However, this method is difficult to control, has a low yield rate, and is costly. Moreover, the silicon substrate, which is not completely insulated, will provide electrons to the buffer layer. The substrate electrons entering the buffer layer increase the leakage current of the buffer layer, which will cause a high leakage current in the buffer layer, which is prone to breakdown and device damage. Summary of the invention

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

[0005] Another object of the present invention is to provide a method for preparing a light emitting diode epitaxial wafer, which is used to prepare the light emitting diode epitaxial wafer mentioned above.

[0006] To achieve this object, the present invention adopts the following technical solutions: A light emitting diode epitaxial wafer 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 stacked in sequence 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 includes a three-dimensional Mg-H doped BAlN layer and a two-dimensional Si3N4 layer stacked in sequence.

[0007] Preferably, the total thickness of the oxide layer is 50 nm to 200 nm; 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.

[0008] Preferably, the total thickness of the barrier layer is 100 nm to 240 nm, and the thickness ratio of the three-dimensional Mg-H doped BAlN layer to the two-dimensional Si3N4 layer is 1:1 to 1:10.

[0009] Preferably, 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.

[0010] Preferably, 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.

[0011] Preferably, 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 .

[0012] Correspondingly, the present invention also provides a method for preparing a light emitting diode epitaxial wafer, which is used to prepare the above-mentioned light emitting diode epitaxial wafer, comprising 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.

[0013] 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; 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.

[0014] 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.

[0015] 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.

[0016] The implementation of the present invention has the following beneficial effects: the present embodiment adopts an oxide layer and a barrier layer to replace the traditional buffer layer, wherein the oxide layer includes a three-dimensional Si gradient doped Ta2O5 layer, a three-dimensional Si gradient doped Ga2O3 layer and a two-dimensional (AlGa)2O3 layer in sequence. 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 the leakage channel 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, while the three-dimensional Si gradient doped Ga2O3 layer ensures the crystal quality of the two-dimensional (AlGa)2O3 layer, Si doping can reduce the generation of screw dislocations, change its extension direction, and thus reduce dislocations; the two-dimensional (AlGa)2O3 layer has a higher bandgap width, between 5eV and 5.3eV, ensuring a higher bandgap width, which can effectively prevent the mobility of electrons, thereby reducing the generation of leakage channels and improving photoelectric performance. The barrier layer of this embodiment includes a three-dimensional Mg-H doped BAlN layer and a two-dimensional Si3N4 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 the dislocation line and improve the crystal quality of the epitaxial layer. In addition, the two-dimensional Si3N4 layer is the last barrier to block the extension of the dislocation, which can further improve the crystal quality of the epitaxial wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a light emitting diode epitaxial wafer in Example 1 of the present invention; Among them, silicon substrate 1, buffer layer 2, undoped AlGaN layer 3, N-type AlGaN layer 4, multi-quantum well layer 5, electron blocking layer 6, P-type AlGaN layer 7, P-type contact layer 8, oxide layer 21, blocking layer 22, three-dimensional Si gradient doped Ta2O5 layer 211, three-dimensional Si gradient doped Ga2O3 layer 212, two-dimensional (AlGa)2O3 layer 213, three-dimensional Mg-H doped BAlN layer 221, two-dimensional Si3N4 layer 222. DETAILED DESCRIPTION

[0018] To make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with 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, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0019] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. Raw materials used without specifying the manufacturer are all conventional products that can be obtained through commercial purchase.

[0020] See also Figure 1 , a light emitting diode epitaxial wafer, comprising a silicon substrate 1, and a buffer layer 2, a non-doped 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; The buffer layer 2 includes an oxide layer 21 and a barrier layer 22 stacked in sequence on the silicon substrate 1; The oxide layer 21 includes a three-dimensional Si gradient doped Ta2O5 layer 211, a three-dimensional Si gradient doped Ga2O3 layer 212 and a two-dimensional (AlGa)2O3 layer 213 which are stacked in sequence; The barrier layer 22 includes a three-dimensional Mg-H doped BAlN layer 221 and a two-dimensional Si3N4 layer 222 which are stacked in sequence.

[0021] It is worth noting that the present embodiment uses an oxide layer 21 and a barrier layer 22 to replace the traditional buffer layer. The oxide layer 21 includes a three-dimensional Si gradient doped Ta2O5 layer 211, a three-dimensional Si gradient doped Ga2O3 layer 212 and a two-dimensional (AlGa)2O3 layer 213 in sequence. 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., a composite layer composed of a buffer layer 2, a non-doped AlGaN layer 3, an N-type AlGaN layer 4, a multi-quantum well layer 5, an electron barrier layer 6, a P-type AlGaN layer 7 and a P-type contact layer 8) can be gradually reduced, the generation of defects can be reduced, and the leakage channel 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-doped Ga2O3 layer 212 can reduce the generation of screw dislocations and change its extension direction while ensuring the crystal quality of the two-dimensional (AlGa)2O3 layer 213. The two-dimensional (AlGa)2O3 layer 213 has a relatively high bandgap width, between 5eV and 5.3eV, which ensures a relatively high bandgap width, can effectively prevent electron migration, reduce electron mobility, thereby reducing the generation of leakage channels and improving photoelectric performance. The barrier layer 22 includes a three-dimensional Mg-H-doped BAlN layer 221 and a two-dimensional Si3N4 layer 222 stacked in sequence, so that the three-dimensional structure layer and the two-dimensional structure layer in the entire buffer layer 2 grow alternately, which can effectively block the extension of the dislocation line and improve the crystal quality of the epitaxial layer. Among them, the two-dimensional Si3N4 layer 222 can change the upward extension direction of the dislocation line, so that two or more dislocation lines intersect and annihilate, playing a blocking role. Therefore, the two-dimensional Si3N4 layer 222 is the last barrier to block the extension of the dislocation, which can further improve the crystal quality of the epitaxial layer. In addition, a three-dimensional Mg-H doped BAlN layer 221 is arranged between the two-dimensional (AlGa)2O3 layer 213 and the two-dimensional Si3N4 layer 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 photoelectric performance of the light-emitting diode.

[0022] It is further explained that by replacing the traditional buffer layer with a combination of an oxide layer 21 and a barrier layer 22, leakage channels can be reduced, crystal quality can be improved, and the optoelectronic performance of the device can be improved, thereby solving the problem of high leakage current in GaN-based LEDs using a silicon substrate as a base.

[0023] Specifically, in a preferred embodiment of the present invention, the silicon substrate 1 is a Si (111) substrate.

[0024] It should be pointed out that the substrate used for the light-emitting diode epitaxial wafer is not limited to a silicon substrate, but may also be other substrates, such as a sapphire substrate, a silicon carbide substrate (such as a SiC (0001) substrate).

[0025] Further explanation, the total thickness of the oxide layer 21 is 50nm~200nm; 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. The thickness ratio of the three-dimensional Si gradient doped Ta2O5 layer 211, the three-dimensional Si gradient doped Ga2O3 layer 212 and the two-dimensional (AlGa)2O3 layer 213 within the above range can reduce the lattice matching and thermal matching between the substrate and the epitaxial layer, which helps to reduce the defects caused by lattice mismatch and thermal mismatch, and because the thickness of the two-dimensional (AlGa)2O3 layer 213 is thicker, it can better prevent the migration of electrons, thereby reducing the generation of leakage channels, thereby improving the light efficiency and reliability of the light-emitting diode.

[0026] The thickness ratios of the three-dimensional Si graded-doped Ta2O5 layer 211, the three-dimensional Si graded-doped Ga2O3 layer 212 and the two-dimensional (AlGa)2O3 layer 213 are exemplarily 1:1:3, 1:1:4, 1:1:5, 1:1:6, 1:1:7, 1:1.5:6, 1:2:7, but are not limited thereto.

[0027] More preferably, in the technical solution, the thickness ratio of the three-dimensional Si gradient doped Ta2O5 layer 211, the three-dimensional Si gradient doped Ga2O3 layer 212 and the two-dimensional (AlGa)2O3 layer 213 is 1:1:5.

[0028] To further illustrate, the thickness of the barrier layer 22 is 100nm~240nm; the thickness ratio of the three-dimensional Mg-H doped BAlN layer 221 and the two-dimensional Si3N4 layer 222 is 1:1~1:10, exemplarily 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, but not limited thereto.

[0029] More preferably, the thickness of the two-dimensional Si3N4 layer 222 is greater than the thickness of the three-dimensional Mg-H doped BAlN layer 221. The material of the two-dimensional Si3N4 layer 222 is Si3N4, which has a strong masking ability and a high dielectric property. The two-dimensional Si3N4 layer 222 is used as the outermost layer of the buffer layer 2, which can effectively block the extension of the dislocation line, and when the thickness of the two-dimensional Si3N4 layer 222 is thicker, it can play a better blocking role, effectively improve the crystal quality of the epitaxial layer, and thus improve the photoelectric performance. Moreover, based on the high dielectric strength and masking ability of Si3N4, the light-emitting diode can obtain a higher breakdown voltage, so that the LED can work normally at a higher voltage without being damaged, and the voltage resistance of the LED is enhanced, so that it can stably emit light under various voltage conditions, and improve the reliability and stability of its application.

[0030] Further explanation, the proportion of Al component in the two-dimensional (AlGa)2O3 layer 213 is 0.3-0.6, and the proportion of Al component increases along the growth direction of the epitaxial wafer. Based on the above improvement, the barrier height of the two-dimensional (AlGa)2O3 layer 213 is continuously increased, which can gradually reduce the upward migration of bottom electrons, thereby reducing the generation of leakage channels.

[0031] Further explanation, the Si doping concentration in the three-dimensional Si gradient doped Ta2O5 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; The doping concentration of Si in the three-dimensional Si gradient doped Ga2O3 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; The doping concentration of Si in the three-dimensional Si-gradient doped Ta2O5 layer 211 and the three-dimensional Si-gradient doped Ga2O3 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, which can gradually reduce the lattice mismatch and thermal mismatch between the substrate and the epitaxial layer, reduce the generation of defects, and effectively reduce the leakage channel of electrons. At the same time, it effectively compensates 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, and reduces the generation of cracks. While ensuring the crystal quality of the two-dimensional (AlGa)2O3 layer 213, the three-dimensional Si gradient doped Ga2O3 layer 212 can reduce the generation of screw dislocations and change their extension direction, thereby reducing dislocations.

[0032] 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; The Mg doping concentration in the three-dimensional Mg-H doped BAlN layer 221 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 .

[0033] It is worth noting that the doping efficiency of Mg is related to the H doping concentration. In this embodiment, an appropriate amount of H doping is performed in the three-dimensional Mg-H doped BAlN layer 221, which can improve the effective doping of Mg and effectively improve the hole concentration of 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 the electrons, thereby further reducing the leakage current and improving the photoelectric performance.

[0034] A method for preparing a light emitting diode epitaxial wafer, used for preparing the above-mentioned light emitting diode epitaxial wafer, comprises the following steps: (1) growing the buffer layer 2 on the silicon substrate 1; (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 are sequentially grown on the buffer layer 2 .

[0035] Further explanation, in step (1), the growth temperature of the buffer layer 2 is 800° C. to 1100° C., and the growth pressure is 50 torr to 600 torr; The three-dimensional Si gradient doped Ta2O5 layer 211, the three-dimensional Si gradient doped Ga2O3 layer 212 and the three-dimensional Mg-H doped BAlN layer 221 are all three-dimensional structural layers, and the two-dimensional (AlGa)2O3 layer 213 and the two-dimensional Si3N4 layer 222 are all 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. By controlling the growth pressure of the three-dimensional structural layer to be greater than the growth pressure of the two-dimensional structural layer, the generation of dislocation lines can be reduced, the overall quality of the epitaxial layer can be improved, and the luminous efficiency of the LED can be improved.

[0036] 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.

[0037] Preferably, the growth atmosphere of the buffer layer 2 is a N2-H2-NH3 mixed gas, and the volume ratio of the N2, the H2 and the NH3 in the N2-H2-NH3 mixed gas is 1:1:1~1:10:10.

[0038] Further explanation, in step (2), the growth temperature of the non-doped AlGaN layer 3 is 1000°C~1300°C, the growth pressure is 50torr~500torr, and the thickness is 1μm~5μm. The non-doped AlGaN layer has a higher growth temperature and lower pressure, and the prepared GaN crystal has better quality. At the same time, as the thickness of 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 will be reduced.

[0039] Specifically, the non-doped AlGaN layer 3 is deposited on the buffer layer 2 by metal organic vapor deposition (MOCVD), with a growth temperature of 1000° C. to 1300° C., a growth pressure of 50 torr to 500 torr, and a thickness of 1 μm to 5 μm.

[0040] The growth temperature of the non-doped AlGaN layer 3 is exemplarily 1000°C, 1100°C, 1200°C, 1300°C, but not limited thereto. The growth pressure of the non-doped AlGaN layer 3 is exemplarily 50torr, 100torr, 150torr, 200torr, 250torr, 300torr, 350torr, 400torr, 450torr, 500torr, but not limited thereto. The thickness of the non-doped AlGaN layer 3 is exemplarily 1μm, 2μm, 3μm, 4μm, 5μm, but not limited thereto.

[0041] In an optional embodiment of the present invention, the growth temperature of the non-doped AlGaN layer 3 is 1200° C., the growth pressure is 100 torr, and the growth thickness is 2 μm-3 μm.

[0042] Further explanation, an N-type AlGaN layer 4 is deposited on the non-doped 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 and holes for the UV LED to recombine. Secondly, 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, sufficient thickness of the N-type AlGaN layer can effectively release stress and improve the luminous efficiency of the light-emitting diode.

[0043] 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 .

[0044] In an optional 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 .

[0045] Further explanation, a multi-quantum well layer 5 is deposited on the N-type AlGaN layer 4. The multi-quantum well layer 5 is preferably a periodically alternately stacked Al x Ga 1-x N quantum well layer and Al y Ga 1-y The combination of N quantum barrier layers has a stacking period of 6 to 12, among which Al x Ga 1-x The thickness of the N quantum well layer is 2nm~5nm, the growth temperature is 950℃~1050℃, the growth pressure is 50torr~300torr, and the Al component x is 0.2~0.6; Al y Ga 1-yThe thickness of the N quantum barrier layer is 5nm~15nm, the Al component y is 0.4~0.8, the growth temperature is 850℃~950℃, and the growth pressure is 50torr~300torr. The multi-quantum well layer is the area where electrons and holes recombine. Reasonable structural design can significantly increase the overlap of electron and hole wave functions, thereby improving the luminous efficiency of LED devices.

[0046] More preferably, the stacking period number of the multi-quantum well layer 5 is 8 to 12, wherein Al x Ga 1-x The thickness of the N quantum well layer is 3nm~4nm, the growth temperature is 980℃~1020℃, the growth pressure is 150torr~250torr, and the Al component x is 0.4~0.5; Al y Ga 1-y The thickness of the N quantum barrier layer is 10nm~13nm, the Al composition y is 0.45~0.6, the growth temperature is 880℃~910℃, and the growth pressure is 150torr~250torr.

[0047] In an optional embodiment of the present invention, the stacking period number of the multi-quantum well layer 5 is 9, wherein Al x Ga 1-x The thickness of the N quantum well layer is 3.5 nm, the Al component 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.

[0048] To further illustrate, 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, wherein the Al component is 0.4~0.8, the thickness is 10nm~50nm, the growth temperature is 1000℃~1100℃, and the pressure is 100torr~300torr. It can effectively limit electron overflow, reduce the blocking of holes, improve the injection efficiency of holes into quantum wells, reduce carrier Auger recombination, and improve the luminous efficiency of the light-emitting diode.

[0049] 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.

[0050] In an optional 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.

[0051] Further explanation, a P-type AlGaN layer 7 is deposited on the electron blocking layer 6, the thickness of the P-type AlGaN layer 7 is 100nm~200nm, and the Mg doping concentration is 1×10 19 atoms / cm 3 ~5×10 20 atoms / cm 3 The growth temperature is 1000℃~1100℃, and the growth pressure is 100torr~600torr. Too high Mg doping concentration will damage the crystal quality, while low 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 UV LED epitaxial wafer with a smooth surface.

[0052] More 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 .

[0053] In an optional 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 .

[0054] Further explanation, 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℃~1100℃, and the growth pressure is 100torr~600torr. A P-type contact layer with a higher doping concentration can further reduce the contact resistance.

[0055] More preferably, the thickness of the P-type contact layer 8 is 15 nm to 30 nm, and the Mg doping concentration is 9×10 19 atoms / cm 3 ~3×10 20 atoms / cm 3 The growth temperature is 1030℃~1080℃, and the growth pressure is 150torr~250torr.

[0056] In an optional 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 , The technical solution of the present invention is further described below through examples and comparative examples.

[0057] Example 1 The light emitting diode epitaxial wafer of the present embodiment comprises a silicon substrate 1, and a buffer layer 2, a non-doped 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 stacked in sequence on the silicon substrate 1; the buffer layer 2 comprises an oxide layer 21 and a blocking layer 22 stacked in sequence on the silicon substrate 1; the oxide layer 21 comprises a three-dimensional Si gradually doped Ta2O5 layer 211, a three-dimensional Si gradually doped Ga2O3 layer 212 and a two-dimensional (AlGa)2O3 layer 213 stacked in sequence; the blocking layer 22 comprises a three-dimensional Mg-H doped BAlN layer 221 and a two-dimensional Si3N4 layer 222 stacked in sequence (such as Figure 1 as shown).

[0058] Among them, the total thickness of the oxide layer 21 is 140nm, and the thickness ratio of the three-dimensional Si gradient doped Ta2O5 layer 211, the three-dimensional Si gradient doped Ga2O3 layer 212 and the two-dimensional (AlGa)2O3 layer 213 is 1:1:3; the total thickness of the barrier layer 22 is 175nm, and the thickness ratio of the three-dimensional Mg-H doped BAlN layer 221 and the two-dimensional Si3N4 layer 222 is 1:1.

[0059] The doping concentration of Si in the three-dimensional Si-gradient doped Ta2O5 layer 211 increases from 5×10 15 atoms / cm 3 Linear increase to 1×10 16 atoms / cm 3 ; The doping concentration of Si in the three-dimensional Si-gradient doped Ga2O3 layer 212 increases from 5×10 15 atoms / cm 3 Linear increase to 9×10 15 atoms / cm 3 ; The proportion of Al component in the two-dimensional (AlGa)2O3 layer 213 increases linearly from 0.3 to 0.4 along the growth direction of the epitaxial wafer; The proportion of B component in the three-dimensional Mg-H doped BAlN layer 221 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 , the doping concentration of H is 1×10 18 atoms / cm 3 .

[0060] The method for preparing the light emitting diode epitaxial wafer of this embodiment comprises the following steps: (1) Providing a silicon substrate 1, wherein the silicon substrate 1 is a Si(111) substrate; (2) growing a buffer layer 2 on a silicon substrate 1; the growth temperature of the buffer layer 2 is 950°C, the growth pressures of the three-dimensional Si graded-doped Ta2O5 layer 211, the three-dimensional Si graded-doped Ga2O3 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)2O3 layer 213 and the two-dimensional Si3N4 layer are all 150 torr; (3) 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 are sequentially grown on the buffer layer 2.

[0061] Example 2 The structure and preparation method of the light-emitting diode epitaxial wafer of this embodiment are basically the same as those of embodiment 1, except that: the proportion of B component in the three-dimensional Mg-H doped BAlN layer of this embodiment is 0.05-0.35, and the proportion of B component decreases linearly 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 , the doping concentration of H is 9×10 18 atoms / cm 3 .

[0062] Example 3 The structural composition and preparation method of the light-emitting diode epitaxial wafer of this embodiment are basically the same as those of Example 2, except that: the total thickness of the oxide layer 21 of this embodiment is 140nm, and the thickness ratio of the three-dimensional Si gradient-doped Ta2O5 layer 211, the three-dimensional Si gradient-doped Ga2O3 layer 212 and the two-dimensional (AlGa)2O3 layer 213 is 1:1:5; the thickness of the barrier layer 22 is 175nm, and the thickness ratio of the three-dimensional Mg-H doped BAlN layer 221 and the two-dimensional Si3N4 layer 222 is 1:6.

[0063] Example 4 The structural composition and preparation method of the light-emitting diode epitaxial wafer of this embodiment are basically the same as those of Example 3, except that the proportion of Al component in the two-dimensional (AlGa)2O3 layer 213 of this embodiment is 0.35~0.55, and the proportion of Al component increases linearly from 0.35 to 0.55 along the growth direction of the epitaxial wafer.

[0064] Example 5 The structure and preparation method of the light emitting diode epitaxial wafer of this embodiment are basically the same as those of embodiment 4, except that the doping concentration of Si in the three-dimensional Si gradient doped Ta2O5 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 increases from 7×10 15 atoms / cm 3 Linear increase to 1×10 17 atoms / cm 3 ; The doping concentration of Si in the three-dimensional Si-gradient doped Ga2O3 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 from 5×10 15 atoms / cm 3 Linear increase to 9×10 16 atoms / cm 3 .

[0065] Comparative Example 1 The structural composition and preparation method of the light emitting diode epitaxial wafer of this comparative example are substantially the same as those of Example 1, except that the buffer layer of this comparative example is a traditional buffer layer, specifically, the buffer layer is an AlN buffer layer.

[0066] Comparative Example 2 The structure 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 doping concentration of Si in the three-dimensional Si gradient doped Ta2O5 layer in this comparative example is 7×10 15 atoms / cm 3 , and the Si doping concentration is constant; the Si doping concentration in the three-dimensional Si gradient doped Ga2O3 layer is 5×10 15 atoms / cm 3 , and the Si doping concentration remains constant.

[0067] Comparative Example 3 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 growth pressure of the three-dimensional Si gradient-doped Ta2O5 layer, the three-dimensional Si gradient-doped Ga2O3 layer, the three-dimensional Mg-H doped BAlN layer, the two-dimensional (AlGa)2O3 layer and the two-dimensional Si3N4 layer is 100 torr.

[0068] Comparative Example 4 The structure and preparation method of the light-emitting diode epitaxial wafer of this comparative example are basically the same as those of Example 1, except that: the proportion of B component in the three-dimensional Mg-H doped BAlN layer of this comparative example is 0.1, and the proportion of B component in the three-dimensional Mg-H doped BAlN layer is constant; at the same time, the three-dimensional Mg-H doped BAlN layer of this comparative example is only doped with Mg, and no H is doped, and the Mg doping concentration is 5×10 17 atoms / cm 3 .

[0069] Performance Test: The light-emitting diode epitaxial wafers obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were prepared into 20mil×24mil chips using the same chip process conditions, and 300 LED chips were respectively extracted and their performance was tested on the same LED spot tester: (1) Photoelectric performance: The luminous efficiency was tested at a working current of 120 mA, and the luminous efficiency improvement rate of Examples 1 to 5 and Comparative Examples 2 to 4 compared with Comparative Example 1 was calculated.

[0070] (2) Antistatic ability: The antistatic performance of the chip was tested using an electrostatic meter under the HBM (human body discharge model) model to test the pass rate of the chip that can withstand reverse 4000V static electricity, and the pass rate 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.

[0071] Specifically, the performance test results are shown in Table 1 below.

[0072] Table 1 Performance test results

[0073] 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 leakage channels, improve crystal quality, and thus effectively improve the photoelectric performance of the LED chips.

[0074] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of 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 includes a three-dimensional Mg-H doped BAlN layer and a two-dimensional Si3N4 layer stacked in sequence.

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

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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