阅读说明：本技术 一种低比接触电阻率的p-GaN欧姆接触电极及其制备方法和应用 (P-GaN ohmic contact electrode with low specific contact resistivity and preparation method and application thereof ) 是由 王玮 王宏兴 林芳 问峰 张明辉 陈根强 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种低比接触电阻率的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层为Mg离子注入层,Mg离子浓度≥1×10<Sup>19</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 with low specific contact resistivity, 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 the heavily doped p-GaN layer is an Mg ion implantation layer with Mg ion concentration not less than 1 × 10 19 cm ‑3 . The p-GaN ohmic contact electrode has ohmic contact characteristic of low contact resistivity.)

1. A p-GaN ohmic contact electrode with low specific contact resistivity, 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 the heavily doped p-GaN layer (2) is an Mg ion implantation layer with Mg ion concentration not less than 1 × 10¹⁹cm^-3。

2. The p-GaN ohmic contact electrode with low specific contact resistivity as claimed in claim 1, wherein the heavily doped p-GaN layer (2) has a thickness of 1-10 nm.

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

4. The p-GaN ohmic contact electrode with low specific contact resistance according to 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 with low specific contact resistivity as claimed in claim 1, wherein the ohmic contact electrode forms a specific contact resistivity of 10 or less^-5Ω·cm。

6. Use of the low specific contact resistivity p-GaN ohmic contact electrode according to any one of claims 1 to 5 for 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 with low specific contact resistivity is characterized by comprising the following steps:

step 1, injecting Mg ions into a cleaned and dried p-GaN material layer (1), and carrying out high-temperature annealing treatment to form a heavily doped p-GaN layer (2) on the p-GaN material layer (1), wherein the heavily doped p-GaN layer (2) is an Mg ion injection layer; wherein, in the heavily doped p-GaN layer (2), the concentration of Mg ions is more than or equal to 1 × 10¹⁹cm^-3；

Step 2, depositing a bottom layer contact metal material on the heavily doped p-GaN layer (2) obtained in the step 1 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 with low specific contact resistivity as claimed in claim 7, wherein the step of cleaning and blow-drying the p-GaN material layer in 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 with low specific contact resistivity as claimed in claim 7, wherein in step 1, an ion implanter is used for implanting Mg ions, the ion implantation energy is 30-300 keV, and the implantation dose is 10 keV¹³～10¹⁶cm^-2；

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, wherein the annealing temperature is 600-1100 ℃, and the annealing time is 1-60 min.

10. The method for preparing a p-GaN ohmic contact electrode with low specific contact resistivity as claimed in claim 7, wherein, in step 2,

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.

Technical Field

The invention relates to the technical field of semiconductor materials and devices, in particular to a p-GaN ohmic contact electrode with low specific contact resistivity 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 of wide forbidden band, high breakdown, high frequency and the like, compared with a Si-based semiconductor, the breakdown field strength of a GaN material is more than 10 times, and the excellent value of Baliga is more than 1580 times. 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^-5·cm²Of the order of magnitude of (d).

In summary, a new p-GaN ohmic contact electrode with low specific contact resistivity 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 with low specific contact resistivity, a preparation method and an 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 with low specific contact resistivity, 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 the heavily doped p-GaN layer is an Mg ion implantation layer with Mg ion concentration not less than 1 × 10¹⁹cm^-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 5-50 nm 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 with low specific contact resistivity is applied to electronic components; 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 relates to a preparation method of a p-GaN ohmic contact electrode with low specific contact resistivity, which comprises the following steps:

step 1, injecting Mg ions into a cleaned and dried p-GaN material layer, and carrying out high-temperature annealing treatment to form a heavily doped p-GaN layer on the p-GaN material layer, wherein the heavily doped p-GaN layer is an Mg ion injection layer; wherein, in the p-GaN material layer, the Mg ion concentration in the heavily doped p-GaN layer is more than or equal to 1 × 10¹⁹cm^-3；

Step 2, depositing a bottom layer contact metal material on the heavily doped p-GaN layer obtained in the step 1 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, an ion implanter is adopted for implantation when Mg ions are implanted, the ion implantation energy is 30-300 keV, and the implantation dosage is 10¹³～10¹⁶cm^-2(ii) a 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, wherein the annealing temperature is 600-1100 ℃, and the annealing time is 1-60 min.

The invention has the further improvement that in the step 2, 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:

in the p-GaN ohmic contact electrode, a heavily doped layer with a plurality of nanometers is formed on the surface of the p-GaN material by utilizing the injection and activation treatment of Mg ions, so that the specific contact resistivity of the p-GaN and metal can be reduced, and the electrical performance of an electronic element is improved. Specifically, the heavily doped p-GaN layer is an Mg ion implantation layer with Mg ion concentration not less than 1 × 10¹⁹cm^-3And obtaining a heavily doped p-GaN layer through annealing, and forming ohmic contact with a lower contact resistivity than the contact resistivity by using a tunneling effect generated by a high hole concentration in the heavily doped p-GaN layer.

In the invention, the thickness of the heavily doped p-GaN layer is 1-10 nm; the high hole concentration of the heavily doped p-GaN layer formed by Mg ion injection and activation treatment is beneficial to tunneling of current carriers, and ohmic contact with lower contact resistivity is formed; the tunneling effect does not need to be too thick, a few nanometers being sufficient, which would increase the contact resistance.

The preparation method is used for preparing the p-GaN ohmic contact electrode with low specific contact resistivity, and the heavily doped layer with a few nanometers is formed on the surface of the p-GaN material by utilizing the injection and activation treatment of Mg ions and high-temperature annealing, so that the specific contact resistivity of the p-GaN and metal can be reduced, and good ohmic contact is formed.

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 with low specific contact resistivity according to an embodiment of the present invention;

FIG. 2 is a schematic flow chart of a method for manufacturing a p-GaN ohmic contact electrode with low specific contact resistivity 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 with low specific contact resistivity according to an embodiment of the present invention includes, from bottom to top: the structure comprises a p-GaN material layer 1, a heavily doped p-GaN layer 2(Mg ion injection layer), a bottom contact metal layer 3 and an upper cap metal layer 4.

The p-GaN material layer 1 is made of p-GaN material which is Mg-doped GaN with Mg doping concentration of 1 × 10¹⁸～1×10¹⁹cm^-3Obtained by MOCVD epitaxial doping.

An Mg ion injection layer (heavy doping) is formed or embedded on the surface of the p-GaN material layer 1, the thickness of the Mg ion injection layer, namely the Mg ion injection area, is 1-10 nm, and the concentration of Mg ions is more than or equal to 1 multiplied by 10¹⁹cm^-3. Specifically, the heavily doped p-GaN layer 2 may be an Mg ion implantation layer with Mg ion concentration of 1 × 10 or more¹⁹cm^-3And obtaining a heavily doped p-GaN layer 2 by annealing, and forming ohmic contact with a lower contact resistivity than that of the contact by using a tunneling effect generated by a high hole concentration in the heavily doped p-GaN layer 2.

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

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

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

Referring to fig. 2, a method for manufacturing a p-GaN ohmic contact electrode with low specific contact resistivity 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) injecting Mg ions into the p-GaN material cleaned in the step 1) by using an ion implanter, and carrying out high-temperature annealing treatment to form a heavily doped p-GaN region, namely an Mg ion injection layer;

3) and sequentially depositing bottom layer contact metal and upper layer cap metal on the surface of the heavily doped p-GaN region, and annealing to form good ohmic contact.

Preferably, the ion implantation energy in step 2) is 30-300 keV, and the implantation dose is 10¹³～10¹⁶cm^-2(ii) a 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 600-1100 ℃, and the annealing time is 1-60 minutes.

Preferably, the thickness of the p-GaN heavily doped layer (Mg ion implantation layer) in the step 2) is 1-10 nm, and the doping concentration is more than or equal to 1 multiplied by 10¹⁹cm^-3。

Preferably, the deposition mode in the step 3) is thermal evaporation, electron beam evaporation, sputtering and the like, the thickness of the bottom contact metal layer 3 is 5-50 nm, the material is Ni, Ir, ITO, TiN or NiN and the like, the thickness of the upper cap metal layer 4 is 50-1000 nm, and the material is 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 with low specific contact resistivity is suitable for electronic elements, wherein the electronic elements are probes, Schottky diodes, thyristors, field effect transistors, light emitting diodes, laser diodes, MEMS devices or biosensors.