A p-GaN ohmic contact electrode and its preparation method and application

Abstract

The present invention discloses a method for preparing a p-GaN ohmic contact electrode, comprising the following steps: providing a GaN-based epitaxial wafer, the topmost layer of which is a p-type GaN layer, activating the p-type GaN layer to obtain a first GaN-based epitaxial wafer; etching the p-type GaN layer of the first GaN-based epitaxial wafer to prepare an ohmic contact region to obtain a second GaN-based epitaxial wafer; wet-etching the second GaN-based epitaxial wafer using a hot phosphoric acid solution, and cleaning it to obtain a third GaN-based epitaxial wafer; depositing metal in the ohmic contact region of the third GaN-based epitaxial wafer, and alloying the metal through an annealing process to complete the preparation of the p-GaN ohmic contact electrode. The present invention can significantly improve the ohmic contact performance of p-GaN materials.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor materials and device technologies, and in particular to a p-GaN ohmic contact electrode and a preparation method and application thereof. Background Art

[0002] The research and application of GaN materials are currently at the forefront and hot topic of global semiconductor research. It is a new semiconductor material for the development of microelectronic and optoelectronic devices and, along with other semiconductor materials such as SiC and diamond, is considered a third-generation semiconductor material. Its wide direct band gap, strong atomic bonds, high thermal conductivity, excellent chemical stability, and strong radiation resistance hold great promise for applications in optoelectronics, high-temperature, high-power devices, and high-frequency microwave devices. While GaN-based devices have made considerable progress in recent years, the difficulty of achieving low-resistance p-type GaN ohmic contacts has hindered the development of GaN-based high-temperature, high-power devices.

[0003] The difficulties in achieving p-GaN ohmic contact are as follows:

[0004] (1) The p-GaN carrier concentration is not high; (2) There is a lack of a suitable contact metal, and the metallization process conditions also affect the p-GaN contact resistance; (3) The GaN surface is chemically active and easily absorbs oxygen atoms, thus forming an oxide layer on the surface. (4) When making an ohmic contact on the surface after etching, the characteristics will deteriorate. The damage caused by etching leads to the formation of N vacancies, making p-type ohmic contact more difficult. To obtain a high-quality p-type ohmic contact, the above problems must be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a p-GaN ohmic contact electrode, which can improve the ohmic contact performance of the p-GaN material.

[0006] The technical problem to be solved by the present invention is also to provide a p-GaN ohmic contact electrode having good ohmic contact characteristics.

[0007] In order to solve the above technical problems, the present invention provides a method for preparing a p-GaN ohmic contact electrode, comprising the following steps:

[0008] Providing a GaN-based epitaxial wafer, wherein the uppermost layer of the GaN-based epitaxial wafer is a p-type GaN layer, and performing an activation treatment on the p-type GaN layer to obtain a first GaN-based epitaxial wafer;

[0009] Etching the p-type GaN layer of the first GaN-based epitaxial wafer to form an ohmic contact region, thereby obtaining a second GaN-based epitaxial wafer;

[0010] performing a wet etching treatment on the second GaN-based epitaxial wafer using a hot phosphoric acid solution, and obtaining a third GaN-based epitaxial wafer after cleaning;

[0011] A metal is deposited in the ohmic contact region of the third GaN-based epitaxial wafer, and the metal is alloyed by an annealing process to complete the preparation of the p-GaN ohmic contact electrode.

[0012] In order to solve the above technical problems, the present invention provides another method for preparing a p-GaN ohmic contact electrode, comprising the following steps:

[0013] Providing a GaN-based epitaxial wafer, wherein the uppermost layer of the GaN-based epitaxial wafer is a p-type GaN layer, and performing an activation treatment on the p-type GaN layer to obtain a GaN-based epitaxial wafer A;

[0014] The GaN-based epitaxial wafer A is wet-etched using a hot phosphoric acid solution, and a GaN-based epitaxial wafer B is obtained after cleaning;

[0015] Photolithography is performed on the p-type GaN layer of the GaN-based epitaxial wafer B to prepare an ohmic contact region, thereby obtaining a GaN-based epitaxial wafer C;

[0016] Metal is deposited in the ohmic contact region of the GaN-based epitaxial wafer C, and the metal is alloyed through an annealing process to complete the preparation of the p-GaN ohmic contact electrode.

[0017] In one embodiment, during the wet etching process using hot phosphoric acid solution, the etching time is 2-6 hours and the solution temperature is 60-100°C.

[0018] Preferably, during the wet etching process using hot phosphoric acid solution, the etching time is 3-4 hours and the solution temperature is 70-90°C.

[0019] In one embodiment, the metal deposited in the ohmic contact region is Ni and X metal, and the X metal is selected from one of Au, Ag and TiN;

[0020] The deposition thickness of Ni is 10-20 nm, and the deposition thickness of the X metal is 10-20 nm.

[0021] In one embodiment, the temperature in the annealing process is 500-700° C., the annealing time is 5-15 minutes, and the annealing atmosphere is an O 2 single gas atmosphere, a mixed gas atmosphere of N 2 and O 2 , or a mixed gas atmosphere of O 2 and Ar.

[0022] Preferably, the temperature in the annealing process is 550-600° C., the annealing time is 8-12 min, the annealing atmosphere is a mixed gas atmosphere of N 2 and O 2 , and the volume ratio of N 2 to O 2 is (3-5):1.

[0023] In one embodiment, ICP etching is performed on the p-type GaN layer of the first GaN-based epitaxial wafer to prepare an ohmic contact region;

[0024] The process conditions of the ICP etching are: ICP power of 200-500W, RF rate of 20-50W, reaction chamber pressure of 0.5-3Pa, Cl2 flow rate of 10-50sccm, and N2 flow rate of 1-30sccm.

[0025] In order to solve the above problems, the present invention further provides a p-GaN ohmic contact electrode, which is prepared by the above-mentioned preparation method of the p-GaN ohmic contact electrode.

[0026] Accordingly, the present invention provides an application of the above-mentioned p-GaN ohmic contact electrode, wherein the p-GaN ohmic contact electrode is applied to an electronic component; the electronic component is a detector, a Schottky diode, a thyristor, a field effect transistor, a light-emitting diode, a laser diode, a MEMS device or a biosensor.

[0027] The implementation of the present invention has the following beneficial effects:

[0028] 1. The preparation method of the p-GaN ohmic contact electrode provided by the present invention uses a hot phosphoric acid solution to wet-etch the GaN-based epitaxial wafer to form a large number of acceptor-type Ga vacancies on the p-GaN surface. The Ga vacancies can increase the net hole concentration at the interface, thereby significantly improving the ohmic contact performance of the p-GaN material.

[0029] 2. The preparation method of the p-GaN ohmic contact electrode provided by the present invention comprises the following steps: after etching, the GaN-based epitaxial wafer is wet-etched with a hot phosphoric acid solution. This not only partially removes impurities generated by etching, but also forms a large number of acceptor-type Ga vacancies on the p-GaN surface. The Ga vacancies can increase the net hole concentration at the interface, thereby significantly improving the ohmic contact performance of the p-GaN material.

[0030] 3. The preparation method of the p-GaN ohmic contact electrode provided by the present invention is annealed in a mixed gas atmosphere of oxygen and nitrogen. On the one hand, the hydrogen in the p-GaN surface layer is removed, thereby increasing the p-type carrier concentration at the interface. On the other hand, NiO with p-type properties is formed, which reduces the barrier height of the interface, thereby facilitating the formation of ohmic contact. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The IV characteristics test results of the p-GaN ohmic contact electrodes prepared in Examples 1 to 5 and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0033] In order to solve the above technical problems, the present invention provides a method for preparing a p-GaN ohmic contact electrode, comprising the following steps:

[0034] S1. Providing a GaN-based epitaxial wafer, wherein the uppermost layer of the GaN-based epitaxial wafer is a p-type GaN layer, and performing an activation treatment on the p-type GaN layer to obtain a first GaN-based epitaxial wafer;

[0035] In one embodiment, the activation process uses low-energy electron beam irradiation and / or thermal annealing.

[0036] S2. Etching the p-type GaN layer of the first GaN-based epitaxial wafer to form an ohmic contact region, thereby obtaining a second GaN-based epitaxial wafer;

[0037] In one embodiment, the p-type GaN layer of the first GaN-based epitaxial wafer is etched using one of reactive ion etching (RIE), electron cyclotron resonance plasma etching (ECR), and inductively coupled plasma etching (ICP) to prepare an ohmic contact region.

[0038] In one embodiment, an ohmic contact region is prepared by photolithography on the p-type GaN layer of the first GaN-based epitaxial wafer.

[0039] The RIE process is characterized by a low etch rate, low anisotropy, and more surface damage. Compared to RIE, ECR has a higher plasma concentration, which allows for a higher etch rate, a higher degree of anisotropy, and operates at a lower pressure, resulting in less damage to the material.

[0040] Preferably, ICP etching is performed on the p-type GaN layer of the first GaN-based epitaxial wafer to form an ohmic contact region. More preferably, the ICP etching process conditions are: ICP power of 200-500W, RF power of 20-50W, reaction chamber pressure of 0.5-3Pa, Cl2 flow rate of 10-50sccm, and N2 flow rate of 1-30sccm. ICP can produce high-density plasma at low pressure, making it easier to achieve good etching results compared to other dry etching techniques.

[0041] However, ICP etching is a complex process combining physical sputtering and chemical reactions. Under the bombardment of high-energy ions, the unevenness of the etched material increases significantly. Unintentional doping caused by etching, point defects caused by chemical bond breakage, and contamination from reaction products or mask etching products all severely impact the ohmic contact quality of the etched P-GaN material.

[0042] S3, wet-etching the second GaN-based epitaxial wafer using a hot phosphoric acid solution, and obtaining a third GaN-based epitaxial wafer after cleaning;

[0043] It should be noted that due to the chemical activity of the GaN surface, it easily absorbs oxygen atoms and forms an oxide layer on the surface. This is usually an insulating oxide layer containing Ga2O3 and C impurities. This insulating oxide layer adds an additional barrier height, hindering the transport of carriers from the metal to the semiconductor, thereby increasing the ohmic contact resistivity.

[0044] Existing technologies often use physical or chemical methods to remove surface contamination and oxide layers. Physical removal methods include glow discharge and sputtering, but these methods are ineffective. Chemical etching methods include pre-treatment with one or a combination of hydrochloric acid, nitric acid, hydrofluoric acid, and NH₄S. However, chemical etching pre-treatment with these solutions only removes the oxide layer and also corrodes the material surface to some extent, increasing surface roughness and reducing ohmic contact quality.

[0045] The present invention uses a hot phosphoric acid solution to perform wet etching treatment on the GaN-based epitaxial wafer. Compared with hydrochloric acid, nitric acid and hydrofluoric acid solutions, the hot phosphoric acid solution can form a large number of acceptor-type Ga vacancies on the p-GaN surface. The Ga vacancies can increase the net hole concentration at the interface.

[0046] In one embodiment, during the wet etching process using a hot phosphoric acid solution, the etching time is 2-6 hours and the solution temperature is 60-100°C. When the etching time is less than 2 hours or the solution temperature is less than 60°C, sufficient acceptor-type Ga vacancies cannot be formed on the p-GaN surface, resulting in an inability to significantly increase the net hole concentration in the cross section; when the etching time is greater than 6 hours or the solution temperature is greater than 100°C, the p-GaN surface will be severely damaged, resulting in a sharp increase in surface roughness and a significant reduction in ohmic contact quality. Preferably, during the wet etching process using a hot phosphoric acid solution, the etching time is 3-4 hours and the solution temperature is 70-90°C.

[0047] S4. Depositing metal in the ohmic contact region of the third GaN-based epitaxial wafer, and alloying the metal through an annealing process to complete the preparation of the p-GaN ohmic contact electrode.

[0048] It should be noted that selecting the appropriate contact metal has an impact on reducing ohmic contact. In one embodiment, the metals deposited in the ohmic contact region are Ni and metal X, with the metal X being selected from Au, Ag, and TiN. Using Ni can form p-type NiO, thereby reducing the interface barrier height. Preferably, the Ni deposition thickness is 10-20 nm, and the metal X deposition thickness is 10-20 nm.

[0049] In addition, the metallization process conditions will also affect the p-GaN contact resistance. In one embodiment, the temperature in the annealing process is 500-700°C, the annealing time is 5-15min, and the annealing atmosphere is an O2 single gas atmosphere or a mixed gas atmosphere of N2 and O2 or a mixed gas atmosphere of O2 and Ar. Preferably, the temperature in the annealing process is 550-600°C, the annealing time is 8-12min, and the annealing atmosphere is a mixed gas atmosphere of N2 and O2, and the volume ratio of N2 and O2 is (3-5):1. Annealing is carried out in a mixed gas atmosphere of oxygen and nitrogen under the above conditions. On the one hand, the hydrogen in the p-GaN surface layer is removed, and the interface p-type carrier concentration is increased. On the other hand, NiO with p-type properties is formed, which reduces the barrier height of the interface, thereby facilitating the formation of ohmic contact.

[0050] In addition, in order to solve the above technical problems, the present invention provides another method for preparing a p-GaN ohmic contact electrode, comprising the following steps:

[0051] (1) providing a GaN-based epitaxial wafer, wherein the uppermost layer of the GaN-based epitaxial wafer is a p-type GaN layer, and performing an activation treatment on the p-type GaN layer to obtain a GaN-based epitaxial wafer A;

[0052] (2) wet-etching the GaN-based epitaxial wafer A using a hot phosphoric acid solution, and obtaining a GaN-based epitaxial wafer B after cleaning;

[0053] It should be noted that due to the chemical activity of the GaN surface, it easily absorbs oxygen atoms and forms an oxide layer on the surface. This is usually an insulating oxide layer containing Ga2O3 and C impurities. This insulating oxide layer adds an additional barrier height, hindering the transport of carriers from the metal to the semiconductor, thereby increasing the ohmic contact resistivity.

[0054] Existing technologies often use physical or chemical methods to remove surface contamination and oxide layers. Physical removal methods include glow discharge and sputtering, but these methods are ineffective. Chemical etching methods include pre-treatment with one or a combination of hydrochloric acid, nitric acid, hydrofluoric acid, and NH₄S. However, chemical etching pre-treatment with these solutions only removes the oxide layer and also corrodes the material surface to some extent, increasing surface roughness and reducing ohmic contact quality.

[0055] The present invention uses a hot phosphoric acid solution to perform wet etching treatment on the GaN-based epitaxial wafer. Compared with hydrochloric acid, nitric acid and hydrofluoric acid solutions, the hot phosphoric acid solution can form a large number of acceptor-type Ga vacancies on the p-GaN surface. The Ga vacancies can increase the net hole concentration at the interface.

[0056] In one embodiment, during the wet etching process using a hot phosphoric acid solution, the etching time is 2-6 hours and the solution temperature is 60-100°C. When the etching time is less than 2 hours or the solution temperature is less than 60°C, sufficient acceptor-type Ga vacancies cannot be formed on the p-GaN surface, resulting in an inability to significantly increase the net hole concentration in the cross section; when the etching time is greater than 6 hours or the solution temperature is greater than 100°C, the p-GaN surface will be severely damaged, resulting in a sharp increase in surface roughness and a significant reduction in ohmic contact quality. Preferably, during the wet etching process using a hot phosphoric acid solution, the etching time is 3-4 hours and the solution temperature is 70-90°C.

[0057] (3) performing photolithography on the p-type GaN layer of the GaN-based epitaxial wafer B to prepare an ohmic contact region, thereby obtaining a GaN-based epitaxial wafer C;

[0058] The GaN-based epitaxial wafer is wet-etched with a hot phosphoric acid solution and then subjected to photolithography, thereby achieving good ohmic contact.

[0059] (4) Depositing metal in the ohmic contact region of the GaN-based epitaxial wafer C, and alloying the metal through an annealing process to complete the preparation of the p-GaN ohmic contact electrode.

[0060] The annealing process is described above and will not be repeated here.

[0061] Accordingly, the present invention also provides a p-GaN ohmic contact electrode, produced by the above-described p-GaN ohmic contact electrode preparation method. Preferably, the p-GaN ohmic contact electrode is used in an electronic component; the electronic component is a detector, a Schottky diode, a thyristor, a field-effect transistor, a light-emitting diode, a laser diode, a MEMS device, or a biosensor.

[0062] The present invention is further described below with specific examples:

[0063] Example 1

[0064] This embodiment provides a method for preparing a p-GaN ohmic contact electrode:

[0065] S1. Providing a GaN-based epitaxial wafer, wherein the uppermost layer of the GaN-based epitaxial wafer is a p-type GaN layer, and performing an activation treatment on the p-type GaN layer to obtain a first GaN-based epitaxial wafer;

[0066] S2. Performing ICP etching on the p-type GaN layer of the first GaN-based epitaxial wafer to prepare an ohmic contact region to obtain a second GaN-based epitaxial wafer;

[0067] The process conditions of the ICP etching are: ICP power of 300 W, RF rate of 30 W, reaction chamber pressure of 1.5 Pa, Cl2 flow rate of 35 sccm, and N2 flow rate of 15 sccm.

[0068] S3, wet-etching the second GaN-based epitaxial wafer using a hot phosphoric acid solution, and obtaining a third GaN-based epitaxial wafer after cleaning;

[0069] During the wet etching process using hot phosphoric acid solution, the etching time is 3 hours and the solution temperature is 85°C.

[0070] S4. Depositing metal in the ohmic contact region of the third GaN-based epitaxial wafer, and alloying the metal through an annealing process to complete the preparation of the p-GaN ohmic contact electrode.

[0071] The metals deposited in the ohmic contact region are Ni and Au metals, the Ni deposition thickness is 20 nm, and the X metal deposition thickness is 15 nm.

[0072] In the annealing process, the annealing temperature is 575° C., the annealing time is 10 min, and the annealing atmosphere is a mixed gas of oxygen and nitrogen, wherein the N 2 :O 2 (volume ratio) is 4:1.

[0073] Example 2

[0074] This embodiment provides a method for preparing a p-GaN ohmic contact electrode:

[0075] (1) providing a GaN-based epitaxial wafer, wherein the uppermost layer of the GaN-based epitaxial wafer is a p-type GaN layer, and performing an activation treatment on the p-type GaN layer to obtain a GaN-based epitaxial wafer A;

[0076] (2) wet-etching the GaN-based epitaxial wafer A using a hot phosphoric acid solution, and obtaining a GaN-based epitaxial wafer B after cleaning;

[0077] During the wet etching process using hot phosphoric acid solution, the etching time is 2 hours and the solution temperature is 100°C.

[0078] (3) performing photolithography on the p-type GaN layer of the GaN-based epitaxial wafer B to prepare an ohmic contact region, thereby obtaining a GaN-based epitaxial wafer C;

[0079] (4) Depositing metal in the ohmic contact region of the GaN-based epitaxial wafer C, and alloying the metal through an annealing process to complete the preparation of the p-GaN ohmic contact electrode.

[0080] The metals deposited in the ohmic contact region are Ni and Au metals, the Ni deposition thickness is 20 nm, and the X metal deposition thickness is 15 nm.

[0081] In the annealing process, the annealing temperature is 500° C., the annealing time is 15 minutes, and the annealing atmosphere is oxygen.

[0082] Example 3

[0083] S1. Providing a GaN-based epitaxial wafer, wherein the uppermost layer of the GaN-based epitaxial wafer is a p-type GaN layer, and performing an activation treatment on the p-type GaN layer to obtain a first GaN-based epitaxial wafer;

[0084] S2. Performing ICP etching on the p-type GaN layer of the first GaN-based epitaxial wafer to prepare an ohmic contact region to obtain a second GaN-based epitaxial wafer;

[0085] The process conditions of the ICP etching are: ICP power of 300 W, RF rate of 30 W, reaction chamber pressure of 1.5 Pa, Cl2 flow rate of 35 sccm, and N2 flow rate of 15 sccm.

[0086] S3, wet-etching the second GaN-based epitaxial wafer using a hot phosphoric acid solution, and obtaining a third GaN-based epitaxial wafer after cleaning;

[0087] During the wet etching process using hot phosphoric acid solution, the etching time is 6 hours and the solution temperature is 60°C.

[0088] S4. Depositing metal in the ohmic contact region of the third GaN-based epitaxial wafer, and alloying the metal through an annealing process to complete the preparation of the p-GaN ohmic contact electrode.

[0089] The metals deposited in the ohmic contact region are Ni and Au metals, the Ni deposition thickness is 20 nm, and the X metal deposition thickness is 15 nm.

[0090] In the annealing process, the annealing temperature is 700° C., the annealing time is 5 minutes, and the annealing atmosphere is nitrogen.

[0091] Example 4

[0092] The difference from Example 1 is that in step S4, in the annealing process, the annealing temperature is 700°C, the annealing time is 20 minutes, and the annealing atmosphere is a mixed gas of oxygen and nitrogen, wherein N2:O2 (volume ratio) = 4:1. The rest is the same as Example 1. Example 5

[0093] The difference from Example 1 is that in step S4, the annealing process has an annealing temperature of 750° C., an annealing time of 10 minutes, and an annealing atmosphere of a mixture of oxygen and nitrogen, wherein the volume ratio of N 2 : O 2 is 4:1. The rest is the same as Example 1.

[0094] Comparative Example 1

[0095] The differences from Example 1 are as follows:

[0096] In step S3, the second GaN-based epitaxial wafer is wet-etched with a hot hydrochloric acid solution, and then a metal is deposited on the ohmic contact region of the third GaN-based epitaxial wafer;

[0097] The rest are the same as in Example 1.

[0098] The IV characteristics of the p-GaN ohmic contact electrodes prepared in Examples 1-5 and Comparative Example 1 were tested. The test results are as follows: Figure 1 shown.

[0099] By comparing Example 1 and Comparative Example 1, it can be seen that compared with the hydrochloric acid solution, the wet etching treatment using the hot phosphoric acid solution can obtain a p-GaN ohmic contact electrode with better ohmic contact performance. This is because a large number of acceptor-type Ga vacancies can be formed on the p-GaN surface after the hot phosphoric acid solution treatment, and the Ga vacancies can increase the net hole concentration at the interface.

[0100] Comparing Example 1 with Examples 4 to 5, it can be seen that annealing at too high a temperature or for too long a time is not conducive to the formation of ohmic contact.

[0101] The above is a preferred embodiment of the invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a p-GaN ohmic contact electrode, characterized in that: The following steps are involved: Providing a GaN-based epitaxial wafer, wherein the uppermost layer of the GaN-based epitaxial wafer is a p-type GaN layer, and performing an activation treatment on the p-type GaN layer to obtain a first GaN-based epitaxial wafer; Etching the p-type GaN layer of the first GaN-based epitaxial wafer to form an ohmic contact region, thereby obtaining a second GaN-based epitaxial wafer; The second GaN-based epitaxial wafer is wet-etched using a hot phosphoric acid solution, and after cleaning, a third GaN-based epitaxial wafer is obtained, whereby a large number of acceptor-type Ga vacancies are formed on the surface of the p-type GaN. The Ga vacancies can increase the net hole concentration at the interface. Depositing metal in the ohmic contact region of the third GaN-based epitaxial wafer and alloying the metal through an annealing process to complete the preparation of a p-GaN ohmic contact electrode; During the wet etching process using hot phosphoric acid solution, the etching time is 2-6 hours and the solution temperature is 60-100°C; The temperature in the annealing process is 500-700° C., the annealing time is 5-15 min, and the annealing atmosphere is an O 2 single gas atmosphere, a mixed gas atmosphere of N 2 and O 2 , or a mixed gas atmosphere of O 2 and Ar.

2. A method for preparing a p-GaN ohmic contact electrode, characterized in that: The following steps are involved: Providing a GaN-based epitaxial wafer, wherein the uppermost layer of the GaN-based epitaxial wafer is a p-type GaN layer, and performing an activation treatment on the p-type GaN layer to obtain a GaN-based epitaxial wafer A; The GaN-based epitaxial wafer A is wet-etched using a hot phosphoric acid solution, and after cleaning, a GaN-based epitaxial wafer B is obtained, whereby a large number of acceptor-type Ga vacancies are formed on the surface of the p-type GaN. The Ga vacancies can increase the net hole concentration at the interface; Photolithography is performed on the p-type GaN layer of the GaN-based epitaxial wafer B to prepare an ohmic contact region, thereby obtaining a GaN-based epitaxial wafer C; Depositing metal in the ohmic contact region of the GaN-based epitaxial wafer C, and alloying the metal through an annealing process to complete the preparation of the p-GaN ohmic contact electrode; During the wet etching process using hot phosphoric acid solution, the etching time is 2-6 hours and the solution temperature is 60-100°C; The temperature in the annealing process is 500-700° C., the annealing time is 5-15 min, and the annealing atmosphere is an O 2 single gas atmosphere, a mixed gas atmosphere of N 2 and O 2 , or a mixed gas atmosphere of O 2 and Ar.

3. The method for preparing a p-GaN ohmic contact electrode according to claim 1 or 2, wherein: During the wet etching process using hot phosphoric acid solution, the etching time is 3-4 hours and the solution temperature is 70-90°C.

4. The method for preparing a p-GaN ohmic contact electrode according to claim 1 or 2, wherein: The metal deposited in the ohmic contact region is Ni and X metal, and the X metal is selected from one of Au, Ag and TiN; The deposition thickness of Ni is 10-20 nm, and the deposition thickness of the X metal is 10-20 nm.

5. The method for preparing a p-GaN ohmic contact electrode according to claim 1 or 2, wherein: The temperature in the annealing process is 550-600°C, the annealing time is 8-12 minutes, and the annealing atmosphere is a mixed gas atmosphere of N2 and O2, with the volume ratio of N2 to O2 being (3-5):

1.

6. The method for preparing a p-GaN ohmic contact electrode according to claim 1, wherein: Performing ICP etching on the p-type GaN layer of the first GaN-based epitaxial wafer to prepare an ohmic contact region; The process conditions of the ICP etching are: ICP power of 200~500W, RF rate of 20~50W, reaction chamber pressure of 0.5~3Pa, Cl2 flow rate of 10~50sccm, and N2 flow rate of 1~30sccm.

7. A p-GaN ohmic contact electrode, characterized in that: The p-GaN ohmic contact electrode is prepared by the preparation method of the p-GaN ohmic contact electrode according to any one of claims 1 to 6.

8. Use of the p-GaN ohmic contact electrode as claimed in claim 7 as an electronic component, characterized in that: Applicable to electronic components; the electronic components are detectors, Schottky diodes, thyristors, field effect transistors, light-emitting diodes, laser diodes, MEMS devices or biosensors.

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