CN212010976U

CN212010976U - GaN-based epitaxial structure

Info

Publication number: CN212010976U
Application number: CN202020890872.0U
Authority: CN
Inventors: 房育涛; 林志东; 张恺玄; 刘波亭
Original assignee: Xiamen Sanan Integrated Circuit Co Ltd
Current assignee: Xiamen Sanan Integrated Circuit Co Ltd
Priority date: 2020-05-25
Filing date: 2020-05-25
Publication date: 2020-11-24
Anticipated expiration: 2030-05-25

Abstract

The utility model discloses a GaN-based epitaxial structure, which comprises a substrate, a nucleation layer, a lattice matching multi-quantum well buffer layer and a GaN buffer layer from bottom to top; in the lattice matching multi-quantum well buffer layer, each multi-quantum well period is formed by staggering an InAlGaN potential well layer and an InAlGaN potential well layer, and the lattice constants of the InAlGaN potential well layer and the InAlGaN potential well layer are equal. The utility model discloses utilize the potential well of the interface polarization electric charge formation on barrier layer and potential well layer, exhaust background carrier to obtain the high resistance buffer layer.

Description

GaN-based epitaxial structure

Technical Field

The utility model belongs to the technical field of the semiconductor, in particular to GaN base epitaxial structure.

Background

Gallium nitride (GaN) -based compound semiconductors, an important third-generation wide bandgap semiconductor material, have the advantages of large nitrogen bandgap width, high breakdown field strength, high temperature resistance, high thermal conductivity, large electronic saturation rate, good chemical stability and the like, and are widely used in the manufacture of high-frequency, high-voltage and high-power electronic devices. In addition, GaN can form a heterojunction with an alloy compound such as AlGaN or InAlGaN, and the heterojunction can form a High-concentration two-dimensional Electron gas at an interface due to valence band discontinuity, piezoelectric polarization and spontaneous polarization, so that the heterojunction can be used for manufacturing a High Electron Mobility Transistor (HEMT) device.

The main material properties that affect the HEMT device characteristics are the leakage of the buffer layer and the crystal quality. The buffer layer leakage can cause the increase of the leakage when the device is turned off, the control capability of the grid electrode on the channel current is weakened, and therefore the normal work of the device is influenced. Defects (dislocations, impurities and the like) in the gallium nitride buffer layer can increase electron scattering and electron capture of the device layer, so that the on-resistance and the dynamic characteristics of the device are influenced, and therefore the high-quality buffer layer is also an important index for improving the performance of the device.

The unintentionally doped intrinsic GaN film material grown by the metal organic chemical vapor deposition equipment has higher background electron concentration (10) in the gallium nitride film due to the existence of N-type defects such as oxygen impurities, nitrogen vacancies and the like¹⁶-10¹⁷/cm³Left and right). In order to obtain a gallium nitride-based thin film with a high resistance value, it is desirable to reduce the background electron concentration in the thin film. There are two general categories of methods for compensating for background electrons in gallium nitride films: one is to compensate background electrons by controlling growth conditions to increase the number of P-type impurities or defects in the film to obtain a high-resistance buffer layer; the other type is that a high resistance buffer layer is obtained by introducing a doping source (Fe, Cr, Mg and the like) of metal elements capable of forming deep level defect states or holes in the film growth process and compensating background electrons by utilizing the deep level defect states or the holes. The two methods inevitably sacrifice the crystal quality of the material or introduce heavy metal atoms with strong memory effect to reduce the mobility of the channel 2DEG and influence the electrical property of the device while obtaining high-resistance gallium nitride.

Accordingly, the present inventors have further studied this to develop a GaN-based epitaxial structure, which is thus produced.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a GaN base epitaxial structure is provided utilizes the potential well of the interface polarization electric charge formation on barrier layer and potential well layer, exhausts background carrier to obtain the high resistance buffer layer.

In order to solve the technical problem, the technical solution of the utility model is that:

a GaN-based epitaxial structure comprises a substrate, a nucleating layer, a lattice matching multi-quantum well buffer layer and a GaN buffer layer from bottom to top; in the lattice matching multi-quantum well buffer layer, each multi-quantum well period is formed by staggering an InAlGaN potential well layer and an InAlGaN potential well layer, and the lattice constants of the InAlGaN potential well layer and the InAlGaN potential well layer are equal.

Furthermore, the number of multiple quantum well periods is 5-100.

Further, the thickness of the InAlGaN barrier layer ranges from 10 nm to 100 nm.

Further, the thickness of the AlGaN well layer ranges from 10 nm to 100 nm.

Further, the thickness of the InAlGaN barrier layer was 15nm, and the thickness of the AlGaN well layer was 20 nm.

Further, the material of the substrate is one of silicon, silicon carbide or sapphire.

The lattice constant of AlN in the III-V nitride semiconductor material is 0.3122nm, the lattice constant of GaN is 0.3189nm, the lattice constant of InN is 0.3538nm, and the lattice matching multiple quantum wells formed by InAlGaN/AlGaN heterojunction can reduce the interface stress variation of the multiple quantum wells and improve the stress control of the multiple quantum well structure. In the lattice matching multiple quantum well, the spontaneous polarization strength of the barrier layer and the potential well layer is different, so that residual polarization charges exist at the interface of the barrier layer and the potential well layer. The polarized charges form electron and hole potential wells, which can deplete the barrier layer and the background electrons of the potential well layer in the multiple quantum well and increase the scattering of electrons to obtain a high resistance buffer layer. In addition, In the lattice matching multiple quantum well, the In component is generally less than 5%, and the interface of the lattice matching multiple quantum well has smaller stress, so that the stress of the lattice matching multiple quantum well structure is better controlled. By utilizing the lattice-matched multi-quantum well structure, high resistance is obtained, and simultaneously, stress can be well controlled to obtain a buffer layer with low warpage and high crystal quality.

Drawings

Fig. 1 is a schematic structural diagram of the present invention;

fig. 2 is a schematic structural diagram of the lattice-matched multiple quantum well buffer layer of the present invention.

Description of the reference symbols

The nucleation layer 2 of the substrate 1 is lattice matched with the multiple quantum well buffer layer 3 GaN buffer layer 4.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It should be noted that, if the terms "upper", "lower", "inner", "outer" and other orientations or positional relationships are used in the drawings, or the orientations or positional relationships that are usually placed when the product of this application is used, the description is only for convenience, and the present invention is not limited thereto.

Disclosed is a GaN-based epitaxial structure, as shown in fig. 1, which is a preferred embodiment of the present invention, comprising a substrate 1, a nucleation layer 2, a lattice-matched multiple quantum well buffer layer 3 and a GaN buffer layer 4. And a multi-layer lattice matching multi-quantum well structure is grown in the buffer layer to reduce the background carrier concentration and reduce the leakage of the buffer layer under high pressure.

The forbidden band width of AlN is 6.2eV, the forbidden band width of GaN is only 3.4eV, and the forbidden band width of InN is 0.69eV, so InAlGaN is used as a barrier layer and AlGaN is used as a potential well layer in the lattice-matched multi-quantum well. As shown in fig. 2, in the lattice-matching multi-quantum well buffer layer, each multi-quantum well period is composed of an InAlGaN barrier layer and an AlGaN potential well layer in a staggered manner, and the lattice constants of the InAlGaN barrier layer and the AlGaN potential well layer are equal. Compared with the common AlGaN multi-quantum well structure, the stress in epitaxial growth with little stress change of potential barriers and potential wells in the lattice matching multi-quantum well is easier to control, and the stress control capability is better.

III-V nitride semiconductor materialThe lattice constant of AlN is 0.3122nm, the lattice constant of GaN is 0.3189nm, and the lattice constant of InN is 0.3538nm, so that the components of In, Al and Ga In InAlGaN alloy material satisfy the molecular formula In_yAl_x+4.66yGa_1-x-5.66yWhen N, its lattice constant and molecular formula Al_xGa_1-xN is equal, and the selection of specific x value and y value can be determined by an epitaxial manufacturer according to market requirements.

In the present embodiment, the InAlGaN barrier layer is specifically In_yAl_x+4.66yGa_1-x-5.66yN, 0-90% and x-0%<y is less than or equal to 5 percent, the thickness of the InAlGaN barrier layer is 15nm, and the AlGaN potential well layer is specifically Al_xGa_1-xAnd x is more than or equal to 0% and less than or equal to 90%, and the thickness of the AlGaN potential well layer is 20 nm. Compared with the composition gradient AlGaN multilayer structure, the lattice matching multiple quantum well structure can obtain a buffer layer with higher resistance value due to the existence of a periodic polarization electric field. By using In_yAl_x+4.66yGa_1-x-5.66yN /Al_xGa_1-xThe lattice formed by the N heterojunction is matched with the multiple quantum well, so that the stress change of the interface of the multiple quantum well can be reduced, and the stress control of the multiple quantum well structure is improved. Since the band gap of AlN is 6.2eV, that of GaN is only 3.4eV, and that of InN is 0.69eV, In is present In the lattice-matched MQW_yAl_x+4.66yGa_1-x-5.66yN is a barrier layer, Al_xGa_1-xN is a potential well layer.

Furthermore, the number of the multiple quantum wells is 5-100, so that the phenomenon that the total thickness of the buffer layer is too thick due to excessive number of cycles to cause stress relaxation or crack is avoided.

Further, the thickness of the AlGaN well layer ranges from 10 nm to 100 nm.

Further, the material of the substrate is one of silicon, silicon carbide or sapphire. Make the utility model discloses have more wide application, not only can prepare high resistance GaN base buffer layer, can also regard as the epitaxial average component degressive AlGaN stress regulation and control layer of GaN on the Si substrate, also can prepare the GaN base back of the body barrier layer of high resistance.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the technical scope of the present invention, so that all changes and modifications made according to the claims and the specification of the present invention should fall within the scope covered by the present invention.

Claims

1. A GaN-based epitaxial structure, characterized by: the crystal comprises a substrate, a nucleating layer, a lattice matching multi-quantum well buffer layer and a GaN buffer layer from bottom to top; in the lattice matching multi-quantum well buffer layer, each multi-quantum well period is formed by staggering an InAlGaN potential well layer and an InAlGaN potential well layer, and the lattice constants of the InAlGaN potential well layer and the InAlGaN potential well layer are equal.

2. A GaN-based epitaxial structure according to claim 1, wherein: the number of multiple quantum well periods is 5-100.

3. A GaN-based epitaxial structure according to claim 1, wherein: the thickness range of the InAlGaN barrier layer is 10-100 nm.

4. A GaN-based epitaxial structure according to claim 1, wherein: the thickness of the AlGaN well layer ranges from 10 nm to 100 nm.

5. A GaN-based epitaxial structure according to claim 3 or 4, characterized in that: the thickness of the InAlGaN barrier layer is 15nm, and the thickness of the AlGaN potential well layer is 20 nm.

6. A GaN-based epitaxial structure according to claim 1, wherein: the substrate is made of one of silicon, silicon carbide or sapphire.