阅读说明：本技术 利用MBE再生长的横向结构GaN基JFET器件及其制备方法 (Lateral structure GaN-based JFET device regrown by MBE and preparation method thereof ) 是由 郭慧 陈敦军 陶涛 王科 刘斌 张�荣 郑有炓 于 2019-10-15 设计创作，主要内容包括：本发明公开了一种利用MBE再生长的横向结构GaN基JFET器件及其制备方法。该方法首先利用金属有机物汽相化学沉积装置在硅衬底上外延好半绝缘的3-5μm的GaN层,再外延300nm左右的n-GaN沟道层,然后在外延好的器件结构上刻蚀出陡峭的n沟道台面,接着利用MBE在台面两侧通过掩模选区外延p-GaN,与中间n沟道台面形成横向突变的p-n结,从而构成一种具有横向沟道的结构简单的GaN-JFET。(The invention discloses a lateral structure GaN-based JFET device regrown by using MBE and a preparation method thereof. The method comprises the steps of firstly, extending a semi-insulating GaN layer of 3-5 mu m on a silicon substrate by using a metal organic vapor phase chemical deposition device, extending an n-GaN channel layer of about 300nm, etching a steep n-channel table top on a device structure with good extension, extending p-GaN on two sides of the table top through a mask selection region by using MBE, and forming a transversely abrupt p-n junction with the middle n-channel table top, thereby forming the GaN-JFET with a transverse channel and a simple structure.)

1. a lateral structure GaN-based JFET device regrown with MBE comprising:

a substrate layer;

a semi-insulating GaN layer grown on the substrate layer;

the transverse n-GaN channel table top is positioned on the top surface of the semi-insulating GaN layer;

the two p-GaN mesas are arranged on two sides of the transverse n-GaN channel mesa and are in contact with the transverse n-GaN channel, are positioned on the top surface of the semi-insulating GaN layer, and form two transverse p-n-p GaNp-n junctions with the transverse n-GaN channel mesa;

the source electrode and the drain electrode are respectively arranged at two ends of the top surface of the transverse n-GaN channel table board;

two gate electrodes respectively covering the top surfaces of the two p-GaN mesas.

2. The lateral-structure GaN-based JFET device using MBE regrowth of claim 1, wherein: the substrate layer is a silicon substrate, a sapphire substrate or a SiC substrate.

3. The lateral-structure GaN-based JFET device using MBE regrowth of claim 1, wherein: the height of the semi-insulating GaN layer is 3-5 mu m.

4. The lateral-structure GaN-based JFET device of claim 1, 2, or 3, wherein: the channel width of the transverse n-GaN channel mesa is 200-600nm, and the channel thickness is 600-1200 nm.

5. The lateral-structure GaN-based JFET device of claim 4, wherein: the height of the p-GaN mesa is 50nm higher than that of the n-GaN channel mesa, the size of the p-GaN mesa in the x direction is 15-30 mu m, and the size of the p-GaN mesa in the y direction is 2-10 mu m; the doping concentration of p-GaN is 1 x10¹⁸-1*10¹⁹cm^-3。

6. The lateral-structure GaN-based JFET device of claim 5, wherein: the source electrode and the drain electrode are Ti/Al/Ni/Au multilayer metal prepared by electron beam evaporation, the thickness is 30/150/50/150nm, the size of the x direction is 50-100nm smaller than the channel thickness of the transverse n-GaN channel mesa, and the size of the y direction is 20-30 μm; the gate electrode is made of Ni/Au multilayer metal, the thickness of the gate electrode is 50/100nm, and the size of each direction is slightly smaller than that of the p-GaN mesa.

7. The method of fabricating a lateral structure GaN-based JFET device using MBE regrowth of any of claims 1-6 comprising the steps of:

(1) the MOCVD method is used for depositing a semi-insulating GaN layer and an n-GaN channel layer on the surface of the substrate to grow the semi-insulating GaN: trimethyl gallium and NH₃Respectively as Ga source and N source, and H as carrier gas₂Or N₂The growth temperature is 1000-1100 ℃, and the growth time is 3-5 h; the growth method of the n-GaN channel layer comprises the following steps: the temperature is 950-¹⁸cm^-3The growth time is 15-20 min;

(2) etching the n-GaN channel layer into a steep transverse n-GaN channel mesa by an ICP (inductively coupled plasma) chlorine-based ion etching method, and over-etching by 50-80nm to ensure that the n-GaN is completely etched;

(3) the MBE method deposits a p-GaN table respectively on two sides of a transverse n-GaN channel table through selective area growth, and the specific growth conditions are as follows: the growth temperature is 700-800 ℃, Mg doping is carried out under the condition of Ga-rich growth, and the doping concentration is 2 x10¹⁹cm^-3；

(4) Ti/Al/Ni/Au30/150/50/150nm alloy electrodes are manufactured at two ends of the top surface of the transverse n-GaN channel mesa by an electron beam evaporation method to serve as a source electrode and a drain electrode, and Ni/Au50/100nm gate electrodes are manufactured at the top surface of the p-GaN channel mesa.

Technical Field

The invention relates to a Junction Field Effect Transistor (JFET), in particular to a lateral structure GaN-based JFET device regrown by MBE.

Background

The nitride semiconductor material has the characteristics of wide forbidden bandwidth, high electronic saturation rate, high critical breakdown electric field and the like, so that the transistor with lower on resistance, higher voltage resistance, higher frequency and higher working temperature can be prepared. The Junction Field Effect Transistor (JFET) device has the characteristics of high input impedance, low noise, low power consumption, strong irradiation resistance and the like. Therefore, the JFET based on the GaN material has more outstanding advantages and is expected to have important application in the fields of complementary transistor logic circuits, current sensing amplifiers, analog-to-digital converter drivers, photodiode trans-impedance amplifiers and the like. The JFET epitaxial wafer with the longitudinal structure needs an n-type conductive substrate, the growth process is complex, the cost is high, and the integration is inconvenient. The JFET with the transverse structure has lower epitaxial wafer cost, simple process and easy planar integration; the previously reported lateral structure GaN-based JFET device (document 1) is single pn junction controlled, in the structure of the present invention. The channel is controlled by two pn junctions, and the controllability of the channel is stronger.

Disclosure of Invention

The invention aims to provide a lateral structure GaN-based JFET device regrown by using MBE, which has a simple growth process and is easy to integrate.

The purpose of the invention is realized by the following technical scheme:

a lateral structure GaN-based JFET device regrown with MBE comprising:

a substrate layer;

a semi-insulating GaN layer grown on the substrate layer;

the transverse n-GaN channel table top is positioned on the top surface of the semi-insulating GaN layer;

the two p-GaN table tops are arranged on two sides of the transverse n-GaN channel table top and are in contact with the transverse n-GaN channel, are positioned on the top surface of the semi-insulating GaN layer, and form two GaN p-n junctions of transverse p-n-p with the transverse n-GaN channel table top;

the source electrode and the drain electrode are respectively arranged at two ends of the top surface of the transverse n-GaN channel table board;

two gate electrodes respectively covering the top surfaces of the two p-GaN mesas.

Preferably, the substrate layer is a silicon substrate.

Preferably, the height of the semi-insulating GaN layer is 3-5 μm.

Preferably, the channel width of the transverse n-GaN channel mesa is 200-600nm, and the channel thickness is 600-1200 nm.

Preferably, the height of the p-GaN mesa is 50nm higher than that of the n-GaN channel mesa, the size of the p-GaN mesa in the x direction is 15-30 μm, and the size of the p-GaN mesa in the y direction is 2-10 μm; the doping concentration of p-GaN is 1 x10¹⁸-1*10¹⁹cm^-3。

Preferably, the source electrode and the drain electrode are Ti/Al/Ni/Au multilayer metal prepared by electron beam evaporation, the thickness is 30/150/50/150nm, the size of the X direction is 50-100nm smaller than the channel thickness of the transverse n-GaN channel mesa, and the size of the Y direction is 20-30 μm; the gate electrode is made of Ni/Au multilayer metal, the thickness of the gate electrode is 50/100nm, the size of each direction is slightly smaller than that of the p-GaN table board, the slightly smaller size means that the size of the y direction is 2-10 mu m, the size of the y direction is the same as that of the p-GaN so as to ensure the good control of a channel, and the size of the x direction is 13-28 mu m and is 1-2 mu m less than that of the p-GaN.

The preparation method of the lateral structure GaN-based JFET device by utilizing MBE regrowth comprises the following steps:

(1) the MOCVD method is used for depositing a semi-insulating GaN layer and an n-GaN channel layer on the surface of the substrate to grow the semi-insulating GaN: trimethyl gallium and NH₃Respectively as Ga source and N source, and H as carrier gas₂Or N₂The growth temperature is 1000-1100 ℃, and the growth time is 3-5 h; the growth method of the n-GaN channel layer comprises the following steps: the temperature is 950-¹⁸cm^-3The growth time is 15-20 min;

(2) etching the n-GaN channel layer into a steep transverse n-GaN channel mesa by an ICP (inductively coupled plasma) chlorine-based ion etching method, and over-etching by 50-80nm to ensure that the n-GaN is completely etched;

(3) respectively depositing a p-GaN table-board on two sides of the transverse n-GaN channel table-board through selective area growth by an MBE methodThe specific growth conditions are as follows: the growth temperature is 700-800 ℃, Mg doping is carried out under the condition of Ga-rich growth, and the doping concentration is 2 x10¹⁹cm^-3；

(4) Ti/Al/Ni/Au30/150/50/150nm alloy electrodes are manufactured at two ends of the top surface of the transverse n-GaN channel mesa by an electron beam evaporation method to serve as a source electrode and a drain electrode, and Ni/Au50/100nm gate electrodes are manufactured at the top surface of the p-GaN channel mesa.

The invention realizes the GaN-based junction field effect transistor with the transverse channel by a secondary regrowth method, and the structural device has simple process and easy integration. Compared with the traditional p-type ion implantation method, the method for regrowing the p-GaN twice can obtain a steeper p-n junction interface and reduce material damage. In the single pn junction controlled GaN-based JFET device with the transverse structure, the channel is controlled by two pn junctions, and compared with a single pn junction longitudinal channel, a double pn junction has stronger control capability on the channel and smaller leakage current.

Drawings

Fig. 1 is a schematic structural view of a silicon-based GaN epitaxial wafer obtained in step (1) of example 1.

Fig. 2 is a schematic structural view of a silicon-based GaN epitaxial wafer obtained in step (2) of example 1.

Fig. 3 is a schematic structural view of the GaN JFET device obtained in step (3) of example 1.

Fig. 4 is a schematic structural view of the GaN-on-silicon epitaxial wafer obtained in step (4) of example 1.

Fig. 5 is a schematic structural view of the GaN-on-silicon epitaxial wafer obtained in step (4) of example 1.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.