阅读说明：本技术 一种p-GaN欧姆接触电极及其制备方法和应用 (P-GaN ohmic contact electrode and preparation method and application thereof ) 是由 王玮 王宏兴 张明辉 问峰 林芳 陈根强 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种p?GaN欧姆接触电极及其制备方法和应用，包括：p?GaN材料层，所述p?GaN材料层形成有重掺杂p?GaN层；所述重掺杂p?GaN层上形成有底层接触金属层，所述底层接触金属层上形成有上层盖帽金属层；其中，重掺杂p?GaN层中，Mg掺杂浓度≥1×10<Sup>20</Sup>cm<Sup>?3</Sup>。本发明的p?GaN欧姆接触电极，具有低比接触电阻率的欧姆接触特性。(The invention discloses a p-GaN ohmic contact electrode and a preparation method and application thereof, wherein the preparation method comprises the following steps: the p-GaN material layer is formed with a heavily doped p-GaN layer; a bottom layer contact metal layer is formed on the heavily doped p-GaN layer, and an upper layer cap metal layer is formed on the bottom layer contact metal layer; wherein, in the heavily doped p-GaN layer, the Mg doping concentration is more than or equal to 1 multiplied by 10 20 cm ‑3 . The p-GaN ohmic contact electrode has ohmic contact characteristic of low contact resistivity.)

1. A p-GaN ohmic contact electrode comprising:

a p-GaN material layer (1), wherein a heavily doped p-GaN layer (2) is formed on the p-GaN material layer (1); a bottom layer contact metal layer (3) is formed on the heavily doped p-GaN layer (2), and an upper layer cap metal layer (4) is formed on the bottom layer contact metal layer (3);

wherein, in the heavily doped p-GaN layer (2), the Mg doping concentration is more than or equal to 1 multiplied by 10²⁰cm^-3。

2. The p-GaN ohmic contact electrode of claim 1, wherein the heavily doped p-GaN layer (2) has a thickness of 1-10 nm.

3. The p-GaN ohmic contact electrode of claim 1, wherein the bottom contact metal layer (3) has a thickness of 5-50nm and is made of Ni, Ir, ITO, TiN or NiN.

4. The p-GaN ohmic contact electrode of claim 1, wherein the upper cap metal layer (4) has a thickness of 50-1000 nm and is made of one or more of Al, Au, Pt and Pd.

5. The p-GaN ohmic contact electrode of claim 1, wherein the ohmic contact electrode has a specific contact resistivity of 10 or less^-5Ω·cm。

6. Use of a p-GaN ohmic contact electrode according to any of claims 1 to 5 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, an MEMS device or a biosensor.

7. A preparation method of a p-GaN ohmic contact electrode is characterized by comprising the following steps:

step 1, depositing Mg metal on a cleaned and dried p-GaN material layer (1), and carrying out high-temperature annealing treatment to obtain a sample subjected to high-temperature annealing treatment;

step 2, removing the Mg metal remained on the surface of the sample obtained in the step 1, and forming a heavily doped p-GaN layer (2) below the Mg metal region; wherein, in the heavily doped p-GaN layer (2), the Mg doping concentration is more than or equal to 1 multiplied by 10²⁰cm^-3；

Step 3, depositing a bottom layer contact metal material on the heavily doped p-GaN layer (2) obtained in the step 2 to obtain a bottom layer contact metal layer (3); depositing an upper-layer cap metal material on the bottom-layer contact metal layer (3) to obtain an upper-layer cap metal layer (4); and (4) annealing to form ohmic contact with preset specific contact resistivity.

8. The method for preparing a p-GaN ohmic contact electrode according to claim 7, wherein the step of cleaning and blow-drying the p-GaN material layer (1) in the step 1 specifically comprises: cleaning the p-GaN material by using standard cleaning organic and inorganic cleaning processes, and N after cleaning₂And (5) drying.

9. The method for preparing a p-GaN ohmic contact electrode according to claim 7, wherein in the step 1, the Mg metal is deposited by thermal evaporation, electron beam evaporation or sputtering;

the high-temperature annealing treatment method is rapid annealing heat treatment or furnace tube type annealing heat treatment, and the annealing atmosphere is N₂Or Ar atmosphere, the annealing temperature is 500-900 ℃, and the annealing time is 1-60 minutes.

10. The method according to claim 7, wherein in step 3, the deposition is thermal evaporation, electron beam evaporation or sputtering;

the annealing treatment method is rapid annealing heat treatment or furnace tube typeAnnealing heat treatment in an atmosphere of N₂、O₂And Ar in a single or mixed gas atmosphere, wherein the annealing temperature is 300-600 ℃, and the annealing time is 1-60 minutes.

Technical Field

The invention relates to the technical field of semiconductor materials and devices, in particular to a p-GaN ohmic contact electrode and a preparation method and application thereof.

Background

The first generation of Si and Ge semiconductors brought human beings into the information age, and at the same time, the intellectualization and informatization of electronic systems were also driven. The second generation semiconductors (GaAs, InP, MCT, etc.) bring optoelectronic devices, power electronic devices, radio frequency electronic devices, spatial radiation-resistant devices, etc. to our public, and have revolutionized the information fields of wireless communication, optical communication, etc.

The third generation semiconductor GaN has excellent semiconductor characteristics such as a wide bandgap, high breakdown, and high frequency; compared with a Si-based semiconductor, the breakdown field strength of the GaN material is more than 10 times, and the optimal value of Baliga is more than 1580 times higher than that of the GaN material; compared with other III-V semiconductor materials, the GaN-based heterojunction can generate two-dimensional electron gas with extremely high concentration through strong spontaneous polarization effect when being undoped, and is the first choice in third-generation semiconductor materials. The GaN material has wide application prospect in the fields of radio frequency microwave and power electronics due to the excellent performance.

However, the implementation of the above-described solution requires an ohmic contact electrode with excellent performance as a solid base. Because p-GaN material has a large work function (7.5eV), no proper metal forms excellent ohmic contact; the hole concentration of the Mg-doped p-GaN material is difficult to improve, and the specific ohmic contact resistivity of the p-GaN material is difficult to be made into 10 of the n-GaN material^-6～10^-8cm²The level of (c). The ohmic contact electrode system commonly used for p-GaN material at present is nickel/gold (Ni/Au), and the specific contact resistivity is 10^-4～10^-5cm²Of the order of magnitude of (d).

In view of the above, a new p-GaN ohmic contact electrode is needed to further improve the ohmic contact characteristics of p-GaN.

Disclosure of Invention

The invention aims to provide a p-GaN ohmic contact electrode, a preparation method and application thereof, so as to solve one or more technical problems. The p-GaN ohmic contact electrode has ohmic contact characteristic of low contact resistivity.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention relates to a p-GaN ohmic contact electrode, which comprises:

the p-GaN material layer is formed with a heavily doped p-GaN layer; a bottom layer contact metal layer is formed on the heavily doped p-GaN layer, and an upper layer cap metal layer is formed on the bottom layer contact metal layer;

wherein, in the heavily doped p-GaN layer, the Mg doping concentration is more than or equal to 1 multiplied by 10²⁰cm^-3。

The invention is further improved in that the thickness of the heavily doped p-GaN layer is 1-10 nm.

The invention is further improved in that the bottom contact metal layer is 5-50nm thick and is made of Ni, Ir, ITO, TiN or NiN.

The invention is further improved in that the thickness of the upper-layer cap metal layer is 50-1000 nm, and the upper-layer cap metal layer is made of one or more of Al, Au, Pt and Pd.

The invention is further improved in that the specific contact resistivity formed by the ohmic contact electrode is less than or equal to 10^-5Ω·cm。

The application of the p-GaN ohmic contact electrode is applied to electronic elements; the electronic component is a detector, a Schottky diode, a thyristor, a field effect transistor, a light emitting diode, a laser diode, an MEMS device or a biosensor.

The invention discloses a preparation method of a p-GaN ohmic contact electrode, which comprises the following steps:

step 1, depositing Mg metal on a cleaned and dried p-GaN material layer, and carrying out high-temperature annealing treatment to obtain a sample subjected to high-temperature annealing treatment;

step 2, removing the Mg metal remained on the surface of the sample obtained in the step 1, and forming a heavily doped p-GaN layer below the Mg metal region; wherein, in the heavily doped p-GaN layer, the Mg doping concentration is more than or equal to 1 multiplied by 10²⁰cm^-3；

Step 3, depositing a bottom layer contact metal material on the heavily doped p-GaN layer obtained in the step 2 to obtain a bottom layer contact metal layer; depositing an upper-layer cap metal material on the bottom-layer contact metal layer to obtain an upper-layer cap metal layer; and (4) annealing to form ohmic contact with preset specific contact resistivity.

The further improvement of the invention is that in the step 1, the step of cleaning and drying the p-GaN material layer specifically comprises the following steps: cleaning the p-GaN material by using standard cleaning organic and inorganic cleaning processes, and N after cleaning₂And (5) drying.

The further improvement of the invention is that in the step 1, the deposition of Mg metal adopts a deposition mode of thermal evaporation, electron beam evaporation or sputtering;

the high-temperature annealing treatment method is rapid annealing heat treatment or furnace tube type annealing heat treatment, and the annealing atmosphere is N₂Or Ar atmosphere, the annealing temperature is 500-900 ℃, and the annealing time is 1-60 minutes.

The invention has the further improvement that in the step 3, the deposition mode is thermal evaporation, electron beam evaporation or sputtering;

the annealing treatment method is rapid annealing heat treatment or furnace tube type annealing heat treatment, and the annealing atmosphere is N₂、O₂And Ar in a single or mixed gas atmosphere, wherein the annealing temperature is 300-600 ℃, and the annealing time is 1-60 minutes.

Compared with the prior art, the invention has the following beneficial effects:

according to the p-GaN ohmic contact electrode, the heavily doped layer with a plurality of nanometers is formed on the surface of the p-GaN material, so that the specific contact resistivity of the p-GaN and metal can be reduced, good ohmic contact is formed, and the electrical performance of an electronic element can be improved. Specifically, in the heavily doped p-GaN layer, the Mg doping concentration is more than or equal to 1 multiplied by 10²⁰cm^-3The ohmic contact with the resistivity lower than that of contact is formed by utilizing a tunneling effect generated by high hole concentration in a heavily doped p-GaN layer, and the ohmic contact is obtained by diffusing Mg deposited on the surface of the p-GaN layer and performing subsequent annealing. The high hole concentration of the heavily doped p-GaN layer is beneficial to tunneling of carriers, and ohmic contact with the contact resistivity lower than that of the p-GaN layer is formed.

Furthermore, the thickness of the heavily doped p-GaN layer is 1-10 nm, and the contact resistance is increased if the thickness of the heavily doped layer with the thickness of a few nanometers is enough to form a tunneling effect.

The preparation method is used for preparing the p-GaN ohmic contact electrode, and the Mg metal which is preferentially deposited is used for forming a heavily doped p-GaN layer with a plurality of nanometers by diffusion on the surface of the p-GaN material to reduce the contact resistance of the p-GaN and the metal and form good ohmic contact. Specifically, the p-GaN layer is used for hole transmission, and the resistance is increased when the concentration is too low, and the carrier scattering is increased when the concentration is too high; the heavily doped region is formed in the invention, so that the tunneling effect can be enhanced, and the contact resistance can be reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; it is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

FIG. 1 is a schematic structural diagram of a p-GaN ohmic contact electrode according to an embodiment of the invention;

FIG. 2 is a schematic flow chart of a method for fabricating a p-GaN ohmic contact electrode according to an embodiment of the invention;

in FIG. 1, a layer of 1, p-GaN material; 2. heavily doping the p-GaN layer; 3. a bottom layer contacting the metal layer; 4. and an upper cap metal layer.

Detailed Description

In order to make the purpose, technical effect and technical solution of the embodiments of the present invention clearer, the following clearly and completely describes the technical solution of the embodiments of the present invention with reference to the drawings in the embodiments of the present invention; it is to be understood that the described embodiments are only some of the embodiments of the present invention. Other embodiments, which can be derived by one of ordinary skill in the art from the disclosed embodiments without inventive faculty, are intended to be within the scope of the invention.

Referring to fig. 1, a p-GaN ohmic contact electrode according to an embodiment of the present invention includes, in order from bottom to top: the structure comprises a p-GaN material layer 1, a heavily doped p-GaN layer 2, a bottom contact metal layer 3 and an upper cap metal layer 4.

The p-GaN material of the p-GaN material layer 1 is Mg-doped GaN and is obtained by MOCVD epitaxy; the p-GaN material comprises a heavily doped p-GaN layer 2 with the thickness of 1-10 nm and the Mg doping concentration of more than or equal to 1 multiplied by 10²⁰cm^-3The ohmic contact with the resistivity lower than that of the contact is formed by utilizing the tunneling effect generated by the high hole concentration in the heavily doped p-GaN layer 2 and obtained by diffusing Mg deposited on the surface of the p-GaN and subsequent annealing.

The bottom contact metal layer 3 has a thickness of 5-50nm and is made of Ni, Ir, ITO, TiN, NiN, etc.

The thickness of the upper cap metal layer 4 is 50-1000 nm, and the material is one or more of Al, Au, Pt and Pd.

The specific contact resistivity formed by the p-GaN ohmic contact electrode of the embodiment of the invention is less than or equal to 10^-5Ω·cm。

Referring to fig. 2, a method for fabricating a p-GaN ohmic contact electrode according to an embodiment of the present invention includes the following steps:

1) cleaning the p-GaN material by using a standard cleaning organic and inorganic cleaning process, and N after cleaning₂Drying;

2) depositing Mg metal on the p-GaN material cleaned in the step 1), and carrying out high-temperature annealing treatment to obtain a sample subjected to high-temperature annealing treatment;

3) after the sample is subjected to high-temperature annealing treatment, removing residual Mg metal on the surface after the sample is cleaned by HCl and HF, and forming a highly doped p-GaN region, namely a p-GaN heavily doped layer, below the Mg metal region;

4) and sequentially depositing bottom layer contact metal and upper layer cap metal in the highly doped p-GaN region, and annealing to form good ohmic contact.

Preferably, the Mg metal deposition mode in the step 2) is thermal evaporation, electron beam evaporation, sputtering and the like, the Mg metal thickness is 1-50 nm, the high-temperature annealing treatment method is rapid annealing heat treatment or furnace tube type annealing heat treatment, and the annealing atmosphere is N₂Ar and the like, the annealing temperature is 500-900 ℃, and the annealing time is 1-60 minutes.

Preferably, step (a)In the step 3), the thickness of the p-GaN heavily doped layer is 1-10 nm, and the doping concentration is more than or equal to 1 multiplied by 10²⁰cm^-3。

Preferably, the deposition modes of the bottom layer contact metal and the upper layer cap metal in the step 4) are thermal evaporation, electron beam evaporation, sputtering and the like, the thickness of the bottom layer contact metal layer 3 is 5-50nm, the materials are Ni, Ir, ITO, TiN, NiN and the like, the thickness of the upper layer cap metal layer 4 is 50-1000 nm, and the materials are one or more combinations of Al, Au, Pt and Pd; the annealing treatment method is rapid annealing heat treatment or furnace tube type annealing heat treatment, and the annealing atmosphere is N₂、O₂Ar or the mixed gas thereof, the annealing temperature is 300-600 ℃, and the annealing time is 1-60 minutes.

The p-GaN ohmic contact electrode is suitable for electronic elements, and the electronic elements are detectors, Schottky diodes, thyristors, field effect transistors, light emitting diodes, laser diodes, MEMS devices or biosensors.