Semi-polar GaN substrate preparation method based on (-310) plane gallium oxide single crystal film

Abstract

The invention discloses a semi-polar GaN substrate preparation method based on a (-310) plane gallium oxide single crystal thin film, and the method comprises the steps: (1) carrying out the partial nitridation or complete nitridation of the (-310) plane Ga2O3 single crystal thin film in an ammonia atmosphere or an ammonia-nitrogen mixed atmosphere, so as to form a porous semi-polar GaN layer on the surface of the Ga2O3 single crystal thin film; and (2) epitaxially growing a GaN film on the porous semi-polar GaN layer to obtain the semi-polar GaN substrate. According to the simple method for obtaining the semi-polar GaN and the semi-polar GaN self-supporting substrate, the semi-polar GaN is obtained through nitridation of the (-310) gallium oxide single crystal film, the semi-polar GaN film or the self-supporting substrate is further obtained through thick film epitaxy, and therefore batch preparation of the large-size high-quality low-cost semi-polar GaN is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a semi-polar GaN substrate based on a (-310) gallium oxide single crystal thin film and belongs to the technical field of semiconductor materials. BACKGROUND

[0002] Gallium nitride (GaN) is a direct band gap semiconductor material, has excellent physical and chemical stability, has a large band gap, a high breakdown electric field, a high thermal conductivity, a high electron saturation drift speed, a strong anti-radiation capability and a strong polarization effect and other excellent physical properties, has important applications in the preparation of short-wavelength semiconductor optoelectronic devices and high-frequency, high-voltage and high-temperature microelectronic devices, and can be used for manufacturing blue, purple and ultraviolet light emitting devices, detector devices, high-temperature, high-frequency, high-field and high-power devices, field emission devices, anti-radiation devices, piezoelectric devices and the like.

[0003] Due to the quantum Stark effect (QCSE) caused by the strong spontaneous polarization and piezoelectric polarization characteristics of the c-polar surface GaN, the light emitting efficiency and electro-optical conversion rate of GaN-based optoelectronic devices in the green light band are still far less than those of mature blue light (InGaN) and red light (AlGaInP), and form a clear efficiency trough in the wavelength-electro-optical conversion efficiency graph. There is no polarization electric field in non-polar GaN (m-GaN, a-GaN) material, and GaN can fundamentally avoid the QCSE effect and improve the electron-hole wave function overlap degree in the InGaN / GaN quantum well, and a larger wave function overlap will bring higher optical gain, which can significantly improve the light emitting efficiency of the device. Compared with polar GaN, the polarity of semi-polar (10-11) GaN is greatly reduced, and the same is more advantageous than the traditional c-polar surface gallium nitride in the light emitting device, so the preparation of non-polar / semi-polar gallium nitride has important significance for the light emitting device. However, the growth of high-quality non-polar / semi-polar GaN thin film is very difficult, and the preparation of large-size non-polar / semi-polar GaN substrate is very difficult. At present, the non-polar / semi-polar GaN substrate is cut from the (0001) GaN substrate, and the size is very small, which cannot be mass-produced.

[0004] Gallium oxide (β-Ga2O3) as a new ultra-wide bandgap semiconductor material has a minimum in-plane mismatch of ~2.6% with GaN, and a GaN surface can be formed on it in a high-temperature NH3 atmosphere, which can be used as a substrate for epitaxial growth of GaN. As described in Chinese Patent Document CN109097834A, the inventors of the present application usually grow a gallium oxide film on a sapphire substrate without special treatment, and the surface of the gallium oxide film is usually (-210) face. Nitriding the (-210) face of the gallium oxide film will form a c-face (0001) GaN. In Chinese Patent Document CN114262938B, the inventors of the present application prepared a non-polar a-plane GaN using a (010) face gallium oxide single crystal. The dissociation surface of β-Ga2O3 will undergo surface reconstruction under the action of nitriding in a high-temperature NH3 atmosphere, and the surface reconstruction will produce a surface that matches the GaN lattice, which can be used as a buffer layer for subsequent epitaxial growth of GaN thick film. This homo-substrate epitaxial growth will significantly reduce the stress and dislocation density in the thick film, and improve the quality of the GaN material. In the present patent application, the inventors have also proposed growing a (-310) β-Ga2O3 single crystal film and nitriding it to prepare semi-polar GaN and semi-polar GaN self-supporting substrates. SUMMARY

[0005] The present application discloses a method for preparing a semi-polar GaN substrate based on a (-310) face gallium oxide single crystal film.

[0006] The technical scheme adopted by the present application is: A method for preparing a semi-polar GaN substrate based on a (-310) face gallium oxide single crystal film, comprising the following steps: (1) Partially or completely nitriding a (-310) face Ga2O3 single crystal film in an ammonia atmosphere or an ammonia-nitrogen mixed atmosphere to form a porous semi-polar GaN layer on the surface of the Ga2O3 single crystal film; (2) Epitaxially growing a GaN film on the porous semi-polar GaN layer to obtain a semi-polar GaN substrate.

[0007] Preferably, the (-310) face Ga2O3 single crystal film is grown on the surface of a cut-angle sapphire substrate. Preferably, the (-310) face Ga2O3 single crystal film is grown on the surface of a cut-angle sapphire substrate.

[0008] Preferably, the thickness of the (-310) face Ga2O3 single crystal film is 500 nm to 5 µm.

[0009] Preferably, in step (1), the nitriding treatment is carried out in an ammonia atmosphere or an ammonia-nitrogen mixed atmosphere for 1 to 5 hours at a temperature range of 900 to 1100°C, with an ammonia flow rate of 100 to 5000 seem and a nitrogen flow rate of 100 to 5000 seem.

[0010] Preferably, the Ga2O3 single crystal thin film is grown by a halide vapor phase epitaxy method in step (1), and the GaN film is grown by a halide vapor phase epitaxy method in step (2). The thickness of the GaN film is determined according to requirements.

[0011] Preferably, the growth conditions of the halide vapor phase epitaxy method are as follows: the sample obtained in step (1) is placed in a growth chamber of a halide vapor phase epitaxy growth system, GaCl is generated by the reaction of metallic Ga and HCl or Cl2 as a gallium source in a low-temperature zone at a temperature of 800-900 DEG C; NH3 is used as a nitrogen source in a high-temperature growth zone, and GaCl and NH3 are mixed to generate a reaction, thereby depositing a GaN film on the porous semi-polar GaN layer of the sample to prepare a semi-polar self-supporting GaN substrate, the temperature of the high-temperature zone is 950-1100 DEG C, and the pressure is 1 atmosphere.

[0012] The present application has the following advantages: The present application provides a method for obtaining a semi-polar self-supporting GaN substrate, wherein a gallium oxide single crystal thin film is grown by a halide vapor phase epitaxy method, and semi-polar (10-11) plane gallium nitride is obtained by nitridation, which has more advantages than traditional c-polar plane gallium nitride in light-emitting devices, and a semi-polar GaN self-supporting substrate can be obtained by further thick film homo-epitaxy. The present method can realize batch production of large-size, high-quality and low-cost semi-polar GaN. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The figure is a schematic diagram of the process route of the present application.

[0014] Figure 2 The figure is an SEM image of the sample (-310) plane gallium oxide single crystal after nitridation, which shows a clear layered porous structure. (a) nitridation for 10 minutes, (b) nitridation for 60 minutes.

[0015] Figure 3 The figure is an X-ray diffraction pattern of the sample (-310) plane gallium oxide single crystal thin film after nitridation, which shows that the surface after nitridation is semi-polar (10-11) plane gallium nitride. DETAILED DESCRIPTION

[0016] The present application will be further described below in combination with examples, but the description of the examples does not have any limitation on the protection scope of the present application.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. Furthermore, while this document provides examples of parameters containing specific values, it should be understood that the parameters need not be exactly equal to the corresponding values, but can approximate the corresponding values ​​within acceptable error tolerances or design constraints. Directional terms mentioned in the embodiments, such as “up,” “down,” “front,” “back,” “left,” “right,” etc., are only for reference to the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the scope of protection of this invention.

[0018] Unless otherwise specified, all substances or instruments used in the following examples can be obtained from conventional commercial sources.

[0019] Example 1 like Figure 1 As shown, the method for fabricating a semi-polar GaN substrate based on a (-310) plane gallium oxide single crystal thin film includes the following steps: 1. A (-310) plane gallium oxide single crystal thin film can be prepared by halide vapor phase epitaxy on a sapphire substrate, for example, by the method described in the literature (-310)-Oriented β-Ga₂O₃ grown on (0001) sapphire by halide vapor phase epitaxy: growth and structural characterizations, CrystEngComm, DOI:10.1039 / d3ce00831b. A (-310) plane gallium oxide thin film can be grown on a chamfered sapphire substrate, or other methods for preparing (-310) plane gallium oxide single crystal thin films disclosed in the art can be used. Pure (-310) gallium oxide can be obtained on chamfered sapphire substrates, while (-201) crystal orientation will grow on substrates with other chamfered angles. During nitriding, (001) GaN mixed phase is easy to appear, which affects the quality of GaN substrate.

[0020] 2. After the growth of the gallium oxide single crystal thin film on the (-310) plane in step 1 is completed, the hydrogen chloride source gas is turned off, and the sample is subjected to high-temperature nitriding treatment while maintaining an NH3 atmosphere to obtain a GaN / Ga2O3 composite structure. Parameters: temperature 1050℃, time 1h; atmosphere: ammonia, flow rate 1000sccm. Results are as follows. Figure 2The Ga2O3 / / GaN / / sapphire substrate is obtained by nitriding the Ga2O3 / / sapphire substrate for 1 h. In this embodiment, the Ga2O3 single crystal is partially nitrided to form a composite semi-polar porous GaN / / Ga2O3 / / sapphire substrate. Generally, it is necessary to nitride for more than 1 h to form a GaN layer thick enough on the surface of Ga2O3 to prevent oxygen diffusion. If the nitriding time is increased to more than 2 h, a porous semi-polar GaN / / sapphire substrate can be obtained after the Ga2O3 is completely nitrided.

[0021] 3. On which GaN epitaxy is performed, the surface is porous and long flat, and after being grown to the required size, the semi-polar GaN substrate can be obtained by self-separation after being taken out, as shown in Figure 3 which can be used for the preparation of high-performance GaN-based optoelectronic devices.

[0022] In the literature (Porous single-crystal GaN films obtained by direct top-down nitridation of bulk and film β-Ga2O3, Superlattices and Microstructures 126 (2019) 98-102), the nitridation of (200) plane Ga2O3 single crystal and (-201) plane Ga2O3 thin film was studied, and both of them were nitrided to obtain polar c-plane GaN. Other literatures also give the same result. Chinese patent document CN114262938A discloses the preparation of non-polar a-plane GaN using (010) plane Ga2O3 single crystal.

[0023] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods and are included in the protection scope of the present application.

Claims

1. A method for preparing a semi-polar GaN substrate based on a (-310) plane gallium oxide single crystal thin film, characterized in that, The steps include: (1) partially or fully nitridize the (-310) plane Ga2O3 single crystal thin film in an ammonia atmosphere or an ammonia-nitrogen mixed atmosphere to form a porous semi-polar GaN layer on the surface of the Ga2O3 single crystal thin film; (2) epitaxially grow a GaN film on the porous semi-polar GaN layer to obtain a semi-polar GaN substrate.

2. The method of claim 1, wherein: The (-310) face Ga2O3 single crystal thin film is grown on a sapphire substrate surface having a cut angle.

3. The method of claim 2, wherein: The thickness of the (-310) plane Ga2O3 single crystal thin film is 500 nm to 5 µm.

4. The method of claim 1, wherein: In step (1), the nitridization treatment is performed in an ammonia atmosphere or an ammonia-nitrogen mixed atmosphere for 1 to 5 hours at a temperature ranging from 900 to 1100 °C, with an ammonia flow rate of 100 to 5000 seem and a nitrogen flow rate of 100 to 5000 seem.

5. The method of claim 1-4, wherein: In step (1), the Ga2O3 single crystal thin film is grown by halide vapor phase epitaxy, and in step (2), the GaN film is grown by halide vapor phase epitaxy.

6. The method of claim 5, wherein: In step (2), the growth conditions for the halide vapor phase epitaxy of the GaN film are as follows: the sample obtained in step (1) is placed in a growth chamber of a halide vapor phase epitaxy growth system, GaCl is generated by the reaction of metallic Ga with HCl or Cl2 as a gallium source at a low temperature zone at a temperature of 800 to 900 °C; in a high temperature growth zone, NH3 is used as a nitrogen source, and GaCl and NH3 are mixed to react, thereby depositing a GaN film on the porous semi-polar GaN layer of the sample to prepare a semi-polar self-supporting GaN substrate, with a high temperature zone temperature of 950 to 1100 °C and a pressure of 1 atmosphere.

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