Deep ultraviolet led with single quantum well structure and method of fabricating the same

Abstract

The application discloses a deep ultraviolet LED with a single quantum well structure and a preparation method thereof. The deep ultraviolet LED comprises a sapphire substrate, an AlN intrinsic layer, an n-type AlGaN electron injection layer, a current expansion layer, a modulation quantum well active layer, an electron blocking layer, a p-type AlGaN hole injection layer and a p-type GaN contact layer which are arranged in sequence. In the direction from the current expansion layer to the electron blocking layer, the modulation quantum well active layer comprises a first barrier layer, an undoped barrier layer, a well layer and a second barrier layer which are arranged in sequence. The Al component percentage of the first barrier layer is the same as that of the undoped barrier layer, and the Al component percentage of the first barrier layer is greater than that of the second barrier layer. The application improves the injection efficiency of electrons and holes into the quantum well by modulating the quantum well active layer to form a specific single quantum well structure of the first barrier layer, the undoped barrier layer, the well layer and the second barrier layer, and improves the light-emitting efficiency of the device.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor optoelectronics, and in particular to a deep ultraviolet LED with a single quantum well structure and a preparation method thereof. BACKGROUND

[0002] As an outstanding representative of wide bandgap semiconductor materials, group III nitride has realized high-efficiency blue-green light-emitting diodes (LEDs), lasers and other solid-state light source devices, which have achieved great success in applications such as flat panel displays and white light illumination. In recent years, people expect to apply this high-efficiency light-emitting material to the ultraviolet band to meet the growing demand for ultraviolet light sources. The ultraviolet band can be divided into long-wave ultraviolet (UVA), medium-wave ultraviolet (UVB), short-wave ultraviolet (UVC) and vacuum ultraviolet (VUV) according to its biological effects. Although ultraviolet light cannot be perceived by the human eye, it has a very wide range of applications. Long-wave ultraviolet light sources have great application prospects in medical treatment, ultraviolet curing, ultraviolet lithography, information storage, plant lighting and other fields; and deep ultraviolet light, including medium-wave ultraviolet and short-wave ultraviolet, has an irreplaceable role in sterilization and disinfection, water purification, biochemical detection, non-line-of-sight communication and other aspects.

[0003] At present, in the AlGaN-based deep ultraviolet LED, due to the fact that the electron migration ability is several times higher than the hole migration ability, the first few potential wells close to the n-type electron injection layer in the multi-quantum well active region structure often have low light-emitting efficiency, thereby limiting the overall light-emitting efficiency of the AlGaN-based deep ultraviolet LED. Therefore, it is necessary to propose a new design of the active region structure of the deep ultraviolet LED to solve the above-mentioned existing problems. SUMMARY

[0004] The present application aims to provide a deep ultraviolet LED with a single quantum well structure and a preparation method thereof, which is used to solve the problem that the light-emitting efficiency of the potential well close to the n-type electron injection layer in the multi-quantum well active region structure of the existing deep ultraviolet LED is low, thereby affecting the overall light-emitting efficiency of the device.

[0005] To solve the above technical problems, the first solution provided by the present application is to provide a deep ultraviolet LED with a single quantum well structure, which comprises a sapphire substrate, an AlN intrinsic layer, an n-type AlGaN electron injection layer, a current expansion layer, a modulation quantum well active layer, an electron blocking layer, a p-type AlGaN hole injection layer and a p-type GaN contact layer arranged in sequence. In the direction from the current expansion layer to the electron blocking layer, the modulation quantum well active layer comprises a first barrier layer, an undoped barrier layer, a potential well layer and a second barrier layer arranged in sequence, the Al composition percentage of the first barrier layer is the same as that of the undoped barrier layer, and the Al composition percentage of the first barrier layer is greater than that of the second barrier layer.

[0006] Preferably, the first barrier layer is a single layer of AlGaN doped structure, the undoped barrier layer is a single layer of AlGaN undoped structure, and the thickness of the first barrier layer and the undoped barrier layer satisfies H1≥2*H2, wherein H1 is the thickness of the first barrier layer, and H2 is the thickness of the undoped barrier layer.

[0007] Preferably, the first barrier layer has an Al composition percentage of 50% to 90% and a thickness of 1 nm to 100 nm.

[0008] Preferably, the first barrier layer has a doping concentration of 1 x 1018cm-2 to 1 x 1020cm-2. 17 20 -3 , and the dopant is Si.

[0009] Preferably, the well layer is a single layer of AlGaN doped structure, has an Al composition percentage of 40% to 80%, a thickness of 0.1 nm to 10 nm, and a doping concentration of 1 x 1018cm-2 to 1 x 1020cm-2. 12 17 -3 .

[0010] Preferably, the second barrier layer is a single layer of AlGaN doped structure, has an Al composition percentage of 40% to 80%, a thickness of 1 nm to 100 nm, and a doping concentration of 1 x 1018cm-2 to 1 x 1020cm-2. 12 17 -3 .

[0011] Preferably, the Al composition percentages of the first barrier layer and the second barrier layer satisfy x1≥x2+2%, wherein x1 is the Al composition percentage of the first barrier layer, and x2 is the Al composition percentage of the second barrier layer.

[0012] Preferably, the thicknesses of the first barrier layer, the undoped barrier layer, and the second barrier layer satisfy (H1+H2)≥2*b, wherein b is the thickness of the second barrier layer.

[0013] Preferably, the current spreading layer has a doping concentration of 1 x 1018cm-2 to 1 x 1020cm-2. 15 20 -3 .

[0014] ​​​​​​​​To solve the above technical problems, the second solution provided by the present application is a preparation method of a deep ultraviolet LED with a single quantum well structure, which is used for preparing the deep ultraviolet LED with a single quantum well structure in the first solution, and comprises the following steps: (1) growing a buffer layer in an AlN intrinsic layer on a sapphire substrate at 400-800 DEG C, with a thickness of 10-50 nm; (2) increasing the temperature to 1200-1400 DEG C, and growing an AlN intrinsic layer on the buffer layer in the AlN intrinsic layer, with a total thickness of 500-4000 nm; (3) decreasing the temperature to 800-1200 DEG C, and growing an n-type AlGaN electron injection layer on the AlN intrinsic layer, with an Al component percentage of 20-90% and a thickness of 500-4000 nm; (4) maintaining the temperature of step (3), and growing a current spreading layer on the n-type AlGaN electron injection layer, with an Al component percentage of 20-90% and a thickness of 10-300 nm; (5) decreasing the temperature to 700-1100 DEG C, and growing a first barrier layer on the current spreading layer, with an Al component percentage of 50-90%, a thickness of 1-100 nm, and a dopant of Si; (6) maintaining the temperature of step (5), stopping Si doping, and growing an undoped barrier layer on the first barrier layer; (7) maintaining the temperature of step (6), and growing a potential well layer on the undoped barrier layer again by doping, with an Al component percentage of 40-80% and a thickness of 0.1-10 nm; (8) maintaining the temperature of step (7), and growing a second barrier layer on the potential well layer, with an Al component percentage of 40-80% and a thickness of 1-100 nm; (9) growing an electron blocking layer on the second barrier layer at 700-1100 DEG C, with a thickness of 0.1-200 nm, an Al component percentage of 50-100%, and a single-layer AlGaN structure or a superlattice AlGaN periodic structure; (10) growing a p-type AlGaN hole injection layer on the electron blocking layer at 700-1100 DEG C, with an Al component percentage of 10-100%, a thickness of 1-50 nm, and Mg as a p-type dopant; and (11) growing a p-type GaN contact layer on the p-type AlGaN hole injection layer at 400-900 DEG C, with a thickness of 1-20 nm and Mg as a p-type dopant.

[0015] The present application has the following beneficial effects: Different from the prior art, the present application provides a deep ultraviolet LED with a single quantum well structure and a preparation method thereof, the quantum well active layer is modulated and arranged, a specific single quantum well structure is formed by a first barrier layer, an undoped barrier layer, a potential well layer and a second barrier layer, the injection efficiency of electrons and holes into the quantum well is improved, and the light emitting efficiency of the device is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of an embodiment of the deep ultraviolet LED with a single quantum well structure in the present application;

[0017] Figure 2 is a comparison diagram of light output power of the deep ultraviolet LED sample of the comparative example and example 1 in the present application. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0019] For the first solution in the present application, please refer to Figure 1 , Figure 1 is a structural schematic diagram of an embodiment of the deep ultraviolet LED with a single quantum well structure in the present application. The deep ultraviolet LED with a single quantum well structure in the present application comprises, in sequence, a sapphire substrate 1, an AlN intrinsic layer 2, an n-type AlGaN electron injection layer 3, a current spreading layer 4, a modulation quantum well active layer 5, an electron blocking layer 6, a p-type AlGaN hole injection layer 7, and a p-type GaN contact layer 8. In the direction from the current spreading layer 4 to the electron blocking layer 6, the modulation quantum well active layer 5 comprises, in sequence, a first barrier layer 51, an undoped barrier layer 52, a well layer 53, and a second barrier layer 54, the Al composition percentage of the first barrier layer 51 is the same as that of the undoped barrier layer 52, and the Al composition percentage of the first barrier layer 51 is greater than that of the second barrier layer 54.

[0020] Specifically, the first barrier layer is a single-layer AlGaN doped structure, the undoped barrier layer is a single-layer AlGaN undoped structure, and the thicknesses of the first barrier layer and the undoped barrier layer satisfy H1≥2*H2, where H1 is the thickness of the first barrier layer and H2 is the thickness of the undoped barrier layer; the thicknesses of the first barrier layer, the undoped barrier layer, and the second barrier layer satisfy (H1+H2)≥2*b, where b is the thickness of the second barrier layer. The mechanism of this thickness setting mode is that the undoped barrier layer plays a certain blocking role on the migration of electrons to the well, but the thickness of the undoped barrier layer needs to be set appropriately to further balance the migration degree of electrons and holes, so as to improve the radiation recombination efficiency of the active region; an excessively thick undoped barrier layer will excessively inhibit the migration of electrons to the well, and is also not conducive to the cooperation of the migration degree of electrons and holes.

[0021] Specifically, the Al component percentages of the first barrier layer and the second barrier layer satisfy: x1 >= x2 + 2%, wherein x1 is the Al component percentage of the first barrier layer, x2 is the Al component percentage of the second barrier layer, and the Al component percentage of the potential well layer is lower than that of the first barrier layer and the second barrier layer. The above-mentioned setting of the Al component percentages of the film layers is based on the following reason: by setting the Al component percentages of the first barrier layer and the second barrier layer, the Al component percentage of the second barrier layer is relatively low, which can promote the migration of holes to the potential well, and the migration degrees of electrons and holes are further balanced and adapted to improve the radiation recombination efficiency of the active region. The setting mode of the Al component usually has an influence on the doping concentration, and therefore the doping concentrations of the first barrier layer and the second barrier layer need to be set according to the Al component. It can be seen that the present application is essentially to promote the migration degrees of electrons and holes to reach a better balanced state by setting the thickness, Al component and doping concentration on three levels, so as to obtain a better radiation recombination effect.

[0022] The deep ultraviolet LED with the single quantum well structure is prepared by using the MOCVD method. In addition, an n electrode 9 is arranged on the n-type AlGaN electron injection layer by using a conventional method, and a p electrode 10 is arranged on the p-type GaN contact layer to form a complete epitaxial chip structure, and the specific process will not be described here.

[0023] For the second solution of the present application, the preparation method of the deep ultraviolet LED with the single quantum well structure comprises the following steps:

[0024] (1) growing a buffer layer in an AlN intrinsic layer on a sapphire substrate at 400-800℃, and the thickness is 10-50nm.

[0025] (2) increasing the temperature to 1200-1400℃, growing an AlN intrinsic layer on the buffer layer in the AlN intrinsic layer, and the total thickness of the AlN intrinsic layer is 500-4000nm.

[0026] (3) decreasing the temperature to 800-1200℃, growing an n-type AlGaN electron injection layer on the AlN intrinsic layer, the Al component percentage is 20-90%, and the thickness is 500-4000nm.

[0027] (4) maintaining the temperature of step (3), growing a current spreading layer on the n-type AlGaN electron injection layer, the Al component percentage is 20-90%, and the thickness is 10-300nm.

[0028] (5) decreasing the temperature to 700-1100℃, growing a first barrier layer on the current spreading layer, the Al component percentage of the first barrier layer is 50%-90%, the thickness is 1nm-100nm, and the dopant is Si.

[0029] (6) maintaining the temperature of step (5), stopping Si doping, and growing an undoped barrier layer on the first barrier layer.

[0030] (7) maintaining the temperature of step (6), doping again, and growing a potential well layer on the undoped barrier layer, the Al component percentage of the potential well layer being 40% to 80%, and the thickness of the potential well layer being 0.1 nm to 10 nm.

[0031] (8) maintaining the temperature of step (7), and growing a second barrier layer on the potential well layer, the Al component percentage of the second barrier layer being 40% to 80%, and the thickness of the second barrier layer being 1 nm to 100 nm.

[0032] (9) growing an electron blocking layer on the second barrier layer at 700 to 1100 °C, the electron blocking layer being a single-layer AlGaN structure or a superlattice AlGaN periodic structure, the thickness of the electron blocking layer being 0.1 to 200 nm, and the Al component percentage of the electron blocking layer being 50 to 100%.

[0033] (10) growing a p-type AlGaN hole injection layer on the electron blocking layer at 700 to 1100 °C, the Al component percentage of the p-type AlGaN hole injection layer being 10 to 100%, the thickness of the p-type AlGaN hole injection layer being 1 to 50 nm, and Mg being used as a p-type dopant.

[0034] (11) growing a p-type GaN contact layer on the p-type AlGaN hole injection layer at 400 to 900 °C, the thickness of the p-type GaN contact layer being 1 to 20 nm, and Mg being used as a p-type dopant.

[0035] Since the method for preparing the deep ultraviolet LED with a single quantum well structure in the second solution is used to prepare the deep ultraviolet LED with a single quantum well structure in the first solution described above, the structure and function of the deep ultraviolet LED with a single quantum well structure in the two solutions should be consistent.

[0036] The performance effects of the deep ultraviolet LED with a single quantum well structure described above are characterized by specific examples below, and the characterization results are analyzed.

[0037] Example 1

[0038] In this example, the steps for preparing the deep ultraviolet LED with a single quantum well structure are as follows:

[0039] (1) growing a buffer layer in an AlN intrinsic layer on a sapphire substrate at 600 °C, the thickness of the buffer layer being 25 nm.

[0040] (2) increasing the temperature to 1200 °C, and growing an AlN intrinsic layer on the buffer layer in the AlN intrinsic layer, the total thickness of the AlN intrinsic layer being 1000 nm.

[0041] (3) The temperature is lowered to 1000°C, and an n-type AlGaN electron injection layer is grown on the AlN intrinsic layer, wherein the Al component percentage is 50%, and the thickness is 1000 nm.

[0042] (4) The temperature is maintained at 1000°C, and a current spreading layer is grown on the n-type AlGaN electron injection layer, wherein the Al component percentage is 70%, and the thickness is 100 nm.

[0043] (5) The temperature is lowered to 800°C, and a first barrier layer is grown on the current spreading layer, wherein the Al component percentage of the first barrier layer is 60%, the thickness is 20 nm, and the dopant is Si.

[0044] (6) The temperature is maintained at 800°C, Si doping is stopped, and an undoped barrier layer is grown on the first barrier layer, wherein the Al component percentage of the undoped barrier layer is 60%, and the thickness is 10 nm.

[0045] (7) The temperature is maintained at 800°C, and doping is performed again, and a potential well layer is grown on the undoped barrier layer, wherein the Al component percentage of the potential well layer is 45%, and the thickness is 1.8 nm.

[0046] (8) The temperature is maintained at 800°C, and a second barrier layer is grown on the potential well layer, wherein the Al component percentage of the second barrier layer is 55%, and the thickness is 15 nm.

[0047] (9) An electron blocking layer is grown on the second barrier layer at 800°C, wherein the electron blocking layer is a single-layer AlGaN structure, the thickness is 10 nm, and the Al component percentage is 40%.

[0048] (10) A p-type AlGaN hole injection layer is grown on the electron blocking layer at 800°C, wherein the Al component percentage is 40%, the thickness is 20 nm, and Mg is used as the p-type dopant.

[0049] (11) A p-type GaN contact layer is grown on the p-type AlGaN hole injection layer at 600°C, wherein the thickness is 10 nm, and Mg is used as the p-type dopant. After the n-electrode and the p-electrode are set, a deep ultraviolet LED with a single quantum well structure is prepared.

[0050] Comparative Example 1

[0051] In this comparative example, based on the preparation steps of Example 1, the preparation of the undoped barrier layer in step (6) above is removed, and the other steps remain the same as in Example 1. That is, the active region setting method used in Comparative Example 1 is a traditional one containing only a doped barrier layer and a potential well layer.

[0052] Comparative Example 2

[0053] In this comparative example, based on the preparation steps of Example 1, only the thickness of the first barrier layer in the above step (5) and the non-doped barrier layer in step (6) are adjusted. Specifically, the thickness of the first barrier layer and the non-doped barrier layer are both set to 15 nm, and the other steps are consistent with Example 1.

[0054] Comparative Example 3

[0055] In this comparative example, based on the preparation steps of Example 1, only the thickness of the second barrier layer in the above step (8) was adjusted to 30 nm, and the other steps remained consistent with Example 1.

[0056] Comparative Example 4

[0057] In this comparative example, based on the preparation steps of Example 1, only the Al component percentage of the second barrier layer in the above step (8) was adjusted to 60%, and the other steps remained consistent with Example 1.

[0058] The optical power of the above embodiment 1 and comparative examples 1 to 4 was tested, and the results are shown in the attached figure. Figure 2 As shown, in which, combined with the attached Figure 2 The characterized data show that:

[0059] 1) Example 1 is compared with Comparative Example 1. Comparative Example 1 employs a conventional active region configuration comprising a doped barrier layer and a well layer, without providing an undoped barrier layer between the first barrier layer and the well layer. Consequently, the optical output power of Comparative Example 1 is significantly lower than that of Example 1 under various current conditions. This demonstrates that the present invention's introduction of an undoped barrier layer between the first barrier layer and the well layer can improve the device's optical output power.

[0060] 2) The difference between Comparative Example 2 and Example 1 is that the relationship between the first barrier layer and the non-doped barrier layer in Comparative Example 2 does not satisfy the aforementioned definition of H1≥2*H2, that is, the non-doped barrier in Comparative Example 2 is relatively too thick, and when the non-doped barrier is too thick, it will affect the injection efficiency of electrons into the potential well, so that the light output power of the sample in Comparative Example 2 is lower than the light output rate of the sample in Example 1. The difference between Comparative Example 3 and Example 1 is that the thickness relationship between the first barrier layer, the non-doped barrier layer and the second barrier layer in Comparative Example 3 does not satisfy (H1+H2)≥2*b, that is, the second barrier layer in Comparative Example 3 is relatively too thick, and the excessive thickness of the second barrier layer will hinder the injection efficiency of holes into the potential well, so that the light output power of the sample in Comparative Example 3 is lower than the light output power of the sample in Example 1. This proves that the film thicknesses of the first barrier layer, the non-doped barrier layer and the second barrier layer in the present invention need to meet specific setting conditions in order to obtain better device light output effects.

[0061] 3) comparing example 1 with comparative example 4, in comparative example 4, the Al component percentage of the first barrier layer is the same as that of the second barrier layer, but the Al component percentage of the first barrier layer is greater than that of the second barrier layer, so that the light output power of the sample of comparative example 4 is lower than that of the sample of example 1, which proves that in the present application, the aforementioned Al component percentage setting relationship needs to be met to obtain a better device light output effect.

[0062] Different from the prior art, the present application provides a deep ultraviolet LED with a single quantum well structure and a preparation method thereof, by modulating and setting the quantum well active layer, a specific single quantum well structure is formed by a first barrier layer, an undoped barrier layer, a potential well layer and a second barrier layer, the injection efficiency of electrons and holes into the quantum well is improved, and the light emitting efficiency of the device is improved.

[0063] The above-described examples only express the embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A deep ultraviolet LED having a single quantum well structure, characterized by, The deep ultraviolet LED with single quantum well structure comprises, in sequence, a sapphire substrate, an AlN intrinsic layer, an n-type AlGaN electron injection layer, a current spreading layer, a modulation quantum well active layer, an electron blocking layer, a p-type AlGaN hole injection layer, and a p-type GaN contact layer; In the direction from the current spreading layer to the electron blocking layer, the modulation quantum well active layer comprises, in sequence, a first barrier layer, an undoped barrier layer, a well layer, and a second barrier layer, the Al composition percentage of the first barrier layer is the same as that of the undoped barrier layer, and the Al composition percentage of the first barrier layer is greater than that of the second barrier layer; The first barrier layer is a single-layer AlGaN doped structure, the undoped barrier layer is a single-layer AlGaN undoped structure, and the thickness relationship of the first barrier layer, the undoped barrier layer, and the second barrier layer satisfies H1≥2*H2, (H1+H2)≥2*b, where H1 is the thickness of the first barrier layer, H2 is the thickness of the undoped barrier layer, and b is the thickness of the second barrier layer.

2. The deep ultraviolet LED having a single quantum well structure according to claim 1, wherein, The Al composition percentage of the first barrier layer is 50% to 90%, and the thickness is 1 nm to 100 nm.

3. The deep ultraviolet LED having a single quantum well structure according to claim 1, wherein, The first barrier layer has a doping concentration of 1 x 1018 17 1 x 1018 20 cm -3 with a dopant of Si.

4. The deep ultraviolet LED having a single quantum well structure according to claim 1, wherein, The potential well layer is a single layer AlGaN doping structure, the Al component percentage is 40%~80%, the thickness is 0.1nm~10nm, the doping concentration is 1x1018~1x1020cm-3 12 ~1x1018 17 cm -3 .

5. The deep ultraviolet LED having a single quantum well structure as claimed in claim 1, wherein the first and second barrier layers are formed of AlxGa1-xN (0 < x < 1). The second barrier layer is a single-layer AlGaN doped structure, with an Al component percentage of 40% to 80%, a thickness of 1 nm to 100 nm, and a doping concentration of 1 x 1018 to 1 x 1021 cm-3. 12 ~1ⅹ10 17 cm -3 .

6. The deep ultraviolet LED having a single quantum well structure according to claim 5, wherein, The Al composition percentages of the first barrier layer and the second barrier layer satisfy x1≥x2+2%, where x1 is the Al composition percentage of the first barrier layer, and x2 is the Al composition percentage of the second barrier layer.

7. The deep ultraviolet LED having a single quantum well structure as claimed in claim 1, wherein the first and second barrier layers are formed of AlxGa1-xN (0 < x < 1). The doping concentration of the current spreading layer is 1 x 10 15 1 x 10 20 cm -3 .

8. A method of manufacturing a deep ultraviolet LED having a single quantum well structure according to any one of claims 1 to 7, wherein The method comprises the following steps: (1) growing a buffer layer in an AlN intrinsic layer on a sapphire substrate at 400-800°C, with a thickness of 10-50 nm; (2) growing an AlN intrinsic layer on the buffer layer in the AlN intrinsic layer by increasing the temperature to 1200-1400°C, with a total thickness of 500-4000 nm; (3) growing an n-type AlGaN electron injection layer on the AlN intrinsic layer by decreasing the temperature to 800-1200°C, with an Al composition percentage of 20-90% and a thickness of 500-4000 nm; (4) growing a current spreading layer on the n-type AlGaN electron injection layer by maintaining the temperature of step (3), with an Al composition percentage of 20-90% and a thickness of 10-300 nm; (5) growing a first barrier layer on the current spreading layer by decreasing the temperature to 700-1100°C, with an Al composition percentage of 50% to 90%, a thickness of 1 nm to 100 nm, and a dopant of Si; (6) growing an undoped barrier layer on the first barrier layer by maintaining the temperature of step (5) and stopping Si doping; (7) growing a well layer on the undoped barrier layer by maintaining the temperature of step (6) and doping again, with an Al composition percentage of 40% to 80% and a thickness of 0.1 nm to 10 nm; (8) growing a second barrier layer on the well layer by maintaining the temperature of step (7), with an Al composition percentage of 40% to 80% and a thickness of 1 nm to 100 nm; (9) growing an electron blocking layer on the second barrier layer at 700-1100 °C, the electron blocking layer being a single-layer AlGaN structure or a superlattice AlGaN periodic structure, the thickness being 0.1-200 nm, and the Al component percentage being 50-100%; (10) growing a p-type AlGaN hole injection layer on the electron blocking layer at 700-1100 °C, the Al component percentage being 10-100%, the thickness being 1-50 nm, and Mg being used as a p-type dopant; (11) growing a p-type GaN contact layer on the p-type AlGaN hole injection layer at 400-900 °C, the thickness being 1-20 nm, and Mg being used as a p-type dopant.

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