Method for normal-pressure MOCVD epitaxial growth of alpha-Ga2O3 film based on tert-butyl alcohol precursor

Abstract

The invention discloses a method for epitaxial growth of an alpha-Ga2O3 film through normal-pressure MOCVD (Metal Organic Chemical Vapor Deposition) based on a tert-butyl alcohol precursor. Comprising the following steps: cleaning a substrate, and placing the cleaned substrate on a reaction chamber base of metal organic chemical vapor deposition equipment; introducing nitrogen into the reaction chamber, and adjusting the air pressure of the reaction chamber to normal pressure; the substrate in the reaction chamber is subjected to high-temperature pretreatment, and the conditions of the high-temperature pretreatment are 1000-1200 DEG C and 15-30 min; cooling the substrate to 570-630 DEG C, and growing an alpha-Ga2O3 film sample on the substrate by taking triethyl gallium as a gallium source precursor and tert-butyl alcohol as an oxygen source precursor; and cooling the alpha-Ga2O3 thin film sample to room temperature, and introducing nitrogen at the same time to obtain the alpha-Ga2O3 thin film. By utilizing the method disclosed by the invention, the pure-phase metastable alpha-Ga2O3 film which is high in quality and grows at a high speed can be prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of microelectronic nanomaterials, and in particular to a method for epitaxially growing α-Ga nanoparticles by atmospheric pressure MOCVD based on a tert-butyl alcohol precursor. 2 O 3 Thin film method. Background Art

[0002] Gallium oxide (Ga 2 O 3 ) is a wide bandgap semiconductor material with excellent electrical and optical properties. The most common of its various crystal structures is β-Ga 2 O 3 , with a bandgap of about 4.9 eV, a feature that gives it broad application prospects in the field of optoelectronic devices. Gallium oxide can effectively absorb and emit ultraviolet light, so it is widely used in the manufacture of high-efficiency photodetectors, ultraviolet light-emitting diodes, solar cells and other devices. In addition, gallium oxide also has good electrical conductivity and thermal stability, and has traditionally been used as an insulating layer of Ga-based semiconductor materials and an ultraviolet filter. These excellent properties make gallium oxide play an important role in modern electronic and optoelectronic technologies, providing new possibilities for the development of high-power and high-frequency electronic devices.

[0003] α-GaO 2 O 3 ) is a metastable phase crystal structure of gallium oxide, with unique crystallographic characteristics and physical properties. Its bandgap is wide, usually around 5.1 eV, which makes it have potential application value in optoelectronic devices, especially in the field of photoelectric detection that requires high stability and high efficiency. With the help of low-cost sapphire substrate (α-Al 2 O 3 ), it is expected that the large-scale preparation of power and optoelectronic devices with both low cost and high performance advantages will be possible. However, there are still some technical challenges in the preparation of high-quality α-phase gallium oxide films, such as crystal defects and surface roughness. Solving these problems is of great significance for its application in practical devices.

[0004] At present, the preparation of gallium oxide thin films mainly adopts metal organic chemical vapor deposition (MOCVD) technology, in which oxygen is the most commonly used oxygen source. However, the high reactivity of oxygen may lead to complex and violent parasitic reactions and increase the risk of carbon contamination, thereby affecting the electrical and optical properties of the film. In addition, oxygen growth conditions have high requirements on the thermal stability of the substrate, which limits its application on certain low-temperature substrates.

[0005] Metal organic chemical vapor deposition (MOCVD) is a widely used technology for growing semiconductor thin films. It deposits thin films by chemical reactions on the substrate surface. In the preparation of gallium oxide thin films, MOCVD technology can provide precise chemical composition and thickness control, thereby growing high-quality α-Ga 2 O 3 However, the traditional method of growing gallium oxide thin films by metal organic chemical vapor deposition has many problems such as low epitaxial rate and impurity in the film. Therefore, a new MOCVD process is developed to solve these problems and realize α-Ga 2 O 3 The rapid epitaxial growth of thin films is of great significance to the development of microelectronic devices.

[0006] High quality α-Ga 2 O 3 The preparation of thin films has always been a difficult problem in research. Although traditional growth methods such as molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) can produce high-quality thin films, they have problems such as low growth rate, high cost, and difficulty in large-scale production. For example, Ga grown by Fuga Gallium using MBE technology 2 O 3 Although the film exhibits low defect density and high electron mobility, its production process is complex and costly. Therefore, developing a new method that can efficiently grow high-quality gallium oxide films under normal pressure conditions is of great significance for promoting the practical application of this material. This new method can not only reduce production costs and increase growth rates, but also achieve large-scale production to meet the growing market demand. It is of great significance for promoting the practical application of this material. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for epitaxially growing α-Ga nanostructured carbon nanotubes using a tert-butyl alcohol precursor at atmospheric pressure MOCVD. 2 O 3 The method of the present invention can be used to prepare low-roughness, high-speed growth pure phase metastable α-Ga 2 O 3 film.

[0008] To achieve the above purpose, the technical solution designed by the present invention is as follows: The present invention provides a method for epitaxially growing α-Ga nanostructured carbon nanotubes at atmospheric pressure using a tert-butyl alcohol precursor. 2 O 3 The method of the thin film comprises the following steps: (1) Cleaning the substrate and placing the cleaned substrate on a reaction chamber base of a metal organic chemical vapor deposition device; (2) Introduce nitrogen into the reaction chamber and adjust the pressure of the reaction chamber to 700-760 Torr; (3) Performing high temperature pretreatment on the substrate in the reaction chamber, the high temperature pretreatment conditions being 1000-1200°C for 15-30 minutes; (4) Cool the substrate to 570-630°C, use triethylgallium as a gallium source precursor and tert-butyl alcohol as an oxygen source precursor to grow α-Ga on the substrate. 2 O 3 Film samples; (5) For α-Ga 2 O 3 The film sample was cooled to room temperature and nitrogen was introduced to obtain α-Ga 2 O 3 film.

[0009] Furthermore, the substrate is an M-oriented (10-10) sapphire substrate.

[0010] Furthermore, in step (1), the method for cleaning the substrate comprises the following steps: S1: placing the substrate in ultrapure deionized water and performing ultrasonic cleaning; S2: pour out the ultrapure deionized water, add acetone, and perform ultrasonic cleaning; S3: Pour out the acetone, add anhydrous ethanol, and perform ultrasonic cleaning; S4: Pour out the anhydrous ethanol, add ultrapure deionized water and perform ultrasonic cleaning; S5: Pour out the ultrapure deionized water, take out the substrate and blow it dry with nitrogen.

[0011] Furthermore, the ultrasonic cleaning time is 6 to 10 min.

[0012] Furthermore, in step (2), the pressure of the reaction chamber is adjusted to 760 Torr using a vacuum pump.

[0013] Furthermore, in step (3), the high temperature pretreatment is performed at 1000° C. for 30 min.

[0014] Furthermore, in the step (4), the substrate is cooled to 600° C.; Growth of α-Ga 2 O 3 The specific process of the thin film sample is as follows: after introducing tert-butanol and triethylgallium for 20 to 40 minutes, the introduction of triethylgallium is stopped, and the reaction chamber is purged in the tert-butanol atmosphere for 5 to 10 minutes, and the growth is completed.

[0015] Furthermore, the flow rate of triethylgallium is 120-180 sccm, and the flow rate of tert-butyl alcohol is 900-1100 sccm.

[0016] Furthermore, the flow rate of triethylgallium is 150 sccm, and the flow rate of tert-butyl alcohol is 1000 sccm.

[0017] The present invention also provides an α-Ga prepared by the method 2 O 3 Thin film, the α-Ga 2 O 3 The root mean square value of the surface roughness of the film is 6.388~19.774 nm.

[0018] Principle of the present invention: In metal organic chemical vapor deposition (MOCVD) technology, choosing a suitable oxygen source is one of the key factors to achieve high quality oxide film growth. Tert-butyl alcohol (t-BuOH) is an organic oxygen source. Compared with traditional oxygen (O 2 ) has significant advantages.

[0019] 1. The use of tert-butyl alcohol helps to improve the uniformity of the growing film. In the MOCVD process, gas transport and reaction kinetics have an important influence on the uniformity of the film. Tert-butyl alcohol molecules have a large diffusion coefficient in the gas phase, which can better mix with metal organic precursors and be evenly distributed throughout the reaction area. This uniform mixing helps to form a uniform reaction layer on the substrate surface, thereby growing a film with uniform thickness and composition. In contrast, oxygen, as an inorganic gas, has less ideal diffusion and mixing characteristics than organic oxygen sources, especially in complex reactor structures, which may lead to uneven local reactions and affect the uniformity of the film.

[0020] 2. The use of tert-butyl alcohol can reduce carbon pollution. In the MOCVD process, the decomposition of organic precursors will produce carbon impurities. If these impurities are not effectively removed, they will be doped into the growing film and affect its electrical and optical properties. However, tert-butyl alcohol produces fewer carbon atoms during the decomposition process, and the carbon atoms in its structure are easier to remove by optimizing growth conditions (such as carrier gas flow), and the CO in its decomposition products is 2 It can effectively reduce carbon pollution. In contrast, oxygen, as an inorganic gas, although it does not contain carbon itself, has a strong reaction activity, which may lead to incomplete decomposition of metal organic precursors or complex gas phase reactions in the gas phase, thereby increasing the risk of carbon pollution.

[0021] 3. Through experiments, it was found that tert-butyl alcohol can react with triethylgallium at normal pressure to form gallium oxide, and α-Ga2 O 3 The film growth rate is higher, which can effectively reduce the gas pressure cost in the MOCVD system. This feature makes it more economical to use tert-butyl alcohol as an oxygen source in industrial production, reducing the need for low-pressure gas supply, reducing equipment complexity and operating costs.

[0022] 4. α-Ga can grow under normal pressure but cannot grow under low pressure 2 O 3 The phenomenon of the film is mainly determined by the thermodynamic and kinetic equilibrium of the reaction between tert-butanol and triethylgallium. Normal pressure conditions: Under higher pressure, the thermodynamic and kinetic conditions of the reaction system are more conducive to the decomposition and reaction of tert-butanol. Higher pressure can promote the diffusion and mixing of reactant molecules and increase the reaction rate. Low pressure conditions: Under low pressure, the thermodynamic and kinetic conditions of the reaction system are not conducive to the decomposition and reaction of tert-butanol. Lower pressure leads to insufficient diffusion and mixing of reactant molecules, thereby affecting the reaction rate and crystallization quality. In the MOCVD process, tert-butanol is used as an oxygen source and triethylgallium is used as a gallium source to react to generate gallium oxide (Ga 2 O 3 The overall reaction equation of 2Ga(C 2 H 5 ) 3 +3t-BuOH→ Ga 2 O 3 +6C 2 H 6 +3H 2 O; triethylgallium decomposes at high temperature to release gallium atoms, tert-butyl alcohol decomposes at high temperature to provide oxygen atoms, gallium oxide is the target product, and water and ethane escape as by-products. The spontaneity of a chemical reaction can be judged based on the change in Gibbs free energy (ΔG). Under normal pressure conditions, the ΔG of this reaction is 0, the reaction is highly spontaneous.

[0023] Beneficial effects of the present invention: 1. The present invention provides a method for preparing α-Ga based on metal organic chemical vapor deposition 2 O 3 The thin film method significantly improves the α-Ga by precisely controlling the transport process of TEGa and t-BuOH, the molar ratio of the two during epitaxial growth, and high-temperature pretreatment of the substrate and other key processing steps. 2 O 3 The growth rate of the film. This method uses t-BuOH as a new precursor to prepare α-Ga 2 O 3 The thin film opens up new possibilities and breaks through the limitations of traditional oxygen sources. At the same time, the method realizes α-Ga 2O 3 The atmospheric pressure growth of thin films effectively avoids the complex gas management and equipment requirements that may be introduced during low-pressure growth, reduces the performance requirements for growth equipment, and simplifies the process flow. This technological breakthrough not only enriches the industry's ideas for thin film epitaxy, but also opens the way for the realization of α-Ga 2 O 3 The large-scale production of thin films provides strong support, helps to significantly improve production efficiency, reduce production costs, and promote the development of α-Ga 2 O 3 The wide application of thin films in optoelectronics, power electronics and other fields has important economic and social value.

[0024] 2. The present invention is based on α-Ga 2 O 3 Before the epitaxial growth of thin film materials, the substrate is subjected to high temperature pretreatment. This step is a key step, and its main purposes include the following aspects: (1) Removal of surface impurities: Through high-temperature pretreatment, the organic and inorganic pollutants on the surface are decomposed and volatilized, and the impurities on the surface are oxidized and removed, thereby providing a clean surface that is conducive to subsequent epitaxial growth.

[0025] (2) Activating atoms on the substrate surface: High-temperature pretreatment can activate atoms on the substrate surface, increase their chemical activity, and make them more easily react with the precursor of the epitaxial layer, thereby forming a uniform epitaxial layer and improving the growth rate and quality of the epitaxial layer.

[0026] (3) Reducing thermal stress: High-temperature pretreatment can make the substrate and epitaxial layer have closer thermal expansion coefficients during the growth process, thereby reducing the generation of thermal stress and improving the stability of the epitaxial layer.

[0027] 3. The present invention optimizes the film growth environment by adjusting the carrier gas flow rate and the preset gas pressure, which helps to obtain a more uniform film. Better crystal quality and fewer defects are crucial to improving the performance of microelectronic devices.

[0028] 4. The present invention uses tert-butanol (t-BuOH) as an oxygen source precursor for film growth. The use of tert-butanol has certain economy and operation convenience. Compared with oxygen, tert-butanol is a common organic solvent with a relatively low price and is easy to obtain and store in laboratories and industrial production. At the same time, when tert-butanol is used as an oxygen source, the control of reaction conditions is relatively simple, and no complex gas treatment system is required, which reduces the complexity of equipment and operation. This makes tert-butanol an ideal oxygen source choice in MOCVD technology, especially in applications requiring high-quality oxide films. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1Atmospheric pressure MOCVD epitaxial growth of α-Ga based on tert-butyl alcohol precursor 2 O 3 Flow chart of the thin film method; Figure 2 The method for growing α-Ga using tert-butyl alcohol as an oxygen source precursor under normal pressure provided in Example 1 2 O 3 Time spectrum of thin films based on in-situ laser reflection monitoring system; Figure 3 O 2 Growth of α-Ga as an oxygen source precursor under low pressure 2 O 3 Time spectrum of thin films based on in-situ laser reflection monitoring system; Figure 4 α-Ga grown without high temperature pretreatment of substrate 2 O 3 AFM images of thin films; Figure 5 The α-Ga substrate provided in Example 1 is grown by high temperature pretreatment. 2 O 3 AFM images of thin films; Figure 6 The α-Ga provided in Example 1 2 O 3 XRD patterns of thin films; Figure 7 The α-Ga provided in Example 1 2 O 3 XRC-ω rocking curves of the films. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand.

[0031] Example 1 Atmospheric Pressure MOCVD Epitaxial Growth of α-Ga Based on Tert-Butyl Alcohol Precursor 2 O 3 Thin film method This embodiment provides a method for preparing high-performance and high-quality α-Ga on a sapphire substrate using an atmospheric pressure MOCVD (AP-MOCVD) device under normal pressure conditions. 2 O 3 Thin film method, combined with Figure 1 As shown, the following steps are included: 1. Precursors for thin film growth are selected, among which tert-butyl alcohol (t-BuOH) is used as the oxygen source and high-purity triethylgallium (TEGa) is used as the gallium source. All precursors are stored in a water bath with a thermostat to maintain a constant temperature, which is convenient for precise control of the precursor flow rate.

[0032] The water bath containing t-BuOH was controlled at a constant temperature of 32°C by a thermostat, and the water bath containing TEGa was controlled at a constant temperature of 22°C by a thermostat.

[0033] 2. Use M-oriented (10-10) sapphire (α-Al 2 O 3 ) as the growth α-Ga 2 O 3 Substrate of thin film material; clean the M-oriented (10-10) sapphire substrate, place the cleaned and dried M-oriented (10-10) sapphire substrate on the reaction chamber base of metal organic chemical vapor deposition (MOCVD) equipment, and the cleaning process is as follows: (1) Place the substrate in a beaker, add ultrapure deionized water and perform ultrasonic cleaning for 6-10 min. The resistivity of the ultrapure deionized water is greater than 18.25 MΩ. cm; (2) Pour out the ultrapure deionized water, then add acetone and perform ultrasonic cleaning for 6 to 10 minutes; (3) Pour out the acetone, then add anhydrous ethanol and perform ultrasonic cleaning for 6 to 10 minutes; (4) Pour out the anhydrous ethanol, then add ultrapure deionized water and perform ultrasonic cleaning for 6 to 10 minutes; (5) Pour out the ultrapure deionized water, then take out the substrate and blow it dry with nitrogen to ensure that the substrate is clean and free of residual moisture.

[0034] 3. Start the MOCVD equipment and introduce nitrogen (N 2 ) (Nitrogen was introduced until the end of the experiment), after the air in the reaction chamber was exhausted, a vacuum pump was used to adjust the pressure in the reaction chamber to 760 Torr, which is the normal pressure level, to completely exhaust the air in the reaction chamber.

[0035] 4. Start the heating wire to heat the substrate base tray in the reaction chamber at 1000~1200℃N 2 The M-oriented (10-10) sapphire substrate was pretreated at high temperature in an atmosphere for 15 to 30 minutes. The in-situ laser reflectivity meter monitoring system was started to monitor the growth process in real time.

[0036] 5. Then cool the substrate to a temperature suitable for α-Ga 2 O 3The temperature of thin film epitaxial growth is 570~630℃, high purity triethylgallium (TEGa) is used as gallium source precursor, t-BuOH is used as oxygen source precursor, and AP-MOCVD technology is used to grow α-Ga on M-oriented (10-10) sapphire substrate 2 O 3 The film growth time is 20-40 min; stop introducing TEGa, keep the temperature constant, purge the reaction chamber in t-BuOH atmosphere for 5-10 min, and the growth is finished; The experimental parameters are as follows: the flow rate of the group III source (TEGa) is 120~180 sccm, and the flow rate of the group VI source (t-BuOH) is 900~1100 sccm. Under this parameter, the flow ratio (the ratio of the amount of substance) of the group VI source to the group III source (VI / III) is 81.48, the monitoring laser wavelength of the in-situ laser reflectivity meter monitoring system is 163.2 nm, and the carrier gas flow rate of nitrogen is 7000 sccm.

[0037] 6. Turn off the MO source to cool down the temperature and continue to introduce N 2 Clean the pipeline to prevent it from being blocked. After the temperature of the reaction chamber drops to room temperature, remove the α-Ga from the MOCVD equipment. 2 O 3 Thin film samples were obtained by atmospheric pressure MOCVD epitaxial growth based on tert-butyl alcohol precursor. 2 O 3 The α-Ga film obtained in this example 2 O 3 The time spectrum of the in-situ laser reflection monitoring system of the thin film is shown in Figure 2 shown.

[0038] Example 2 Atmospheric Pressure MOCVD Epitaxial Growth of α-Ga Based on Tert-Butyl Alcohol Precursor 2 O 3 Thin film method This embodiment provides a method for preparing high-performance and high-quality α-Ga on a sapphire substrate using an MOCVD device under normal pressure. 2 O 3 The method of preparing the film is the same as that of Example 1, except that: 1. In step 4, the high temperature pretreatment conditions are 1000°C and 30 min; 2. In step 5, α-Ga 2 O 3 The temperature of the epitaxial growth of the thin film is 600°C, the flow rate of triethylgallium is 150 sccm, and the flow rate of tert-butyl alcohol is 1000 sccm.

[0039] Example 3 α-Ga2O3 grown by atmospheric pressure MOCVD epitaxially from tert-butyl alcohol precursor 2 O 3 Study on the properties of thin films 1. Using the in-situ laser reflectivity monitoring system (In-situ Laser Monitoring System) to monitor the growth of α-Ga in Example 1 2 O 3 The film growth process was tested to study the growth rate and film thickness. Three control groups were set up, namely: Control group 1 used tert-butyl alcohol as the oxygen source and low-pressure MOCVD to grow α-Ga 2 O 3 film; Control group 2 used oxygen as the oxygen source and grew α-Ga by MOCVD at normal pressure 2 O 3 film; Control group 3 used oxygen as the oxygen source and low-pressure MOCVD to grow α-Ga 2 O 3 The time spectrum of the in-situ laser reflection monitoring system is as follows: Figure 3 shown.

[0040] According to the in-situ laser reflectivity monitoring system, no growth of α-Ga was found in control group 1 and control group 2. 2 O 3 From the results of control group 1, it can be seen that α-Ga films cannot be prepared under low pressure when tert-butyl alcohol is used as the oxygen source. 2 O 3 From the results of control group 2, it can be seen that α-Ga films cannot be prepared under normal pressure when oxygen is used as the oxygen source. 2 O 3 film.

[0041] Combination Figure 2 and Figure 3 As shown in Figure 2, the film thickness corresponding to a single oscillation cycle is 164.8 nm. The growth rate under normal pressure growth conditions based on tert-butyl alcohol as the oxygen source is 576.8 nm / h, which is much higher than that under low pressure conditions using O 2 The growth rate (428 nm / h) was significantly increased when used as an oxygen source.

[0042] 2. Using atomic force microscopy (AFM) to measure the α-Ga prepared in Example 1 2 O 3 The surface morphology of the film was studied. At the same time, the α-Ga prepared by the method of Example 1 but without the high temperature pretreatment step (i.e., step 4 in Example 1) 2 O 3 The film was used as a control.

[0043] Combination Figure 4 and Figure 5 As shown, the AFM scanning range is 2 2 μm 2 , α-Ga after high temperature pretreatment 2 O 3 The surface of the thin film epitaxial layer is smoother, and its surface roughness is significantly lower than that of α-Ga without high temperature pretreatment. 2 O 3 Thin film epitaxial layer. α-Ga without high temperature pretreatment 2 O 3 The root mean square (RMS) of the surface roughness of the thin film epitaxial layer is 47.655 nm. 2 O 3 The thin film epitaxial layer (i.e., the α-Ga 2 O 3 The RMS of the thin film) is 11.799 nm, which proves that the high temperature pretreatment has a significant improvement on the quality of the thin film epitaxial layer.

[0044] 3. X-ray diffraction (XRD) technology was used to analyze the α-Ga 2 O 3 The crystal quality of the film is characterized. Figure 6 As shown in the figure, a single and strong (30-30) crystal plane diffraction peak was observed at a diffraction angle (2θ) of 64.76°, indicating that α-Ga 2 O 3 The films have good crystal orientation, demonstrating the effectiveness of the growth process.

[0045] 4. Using the ω rocking curve in X-ray diffraction (XRD) technology to analyze the α-Ga 2 O 3 The crystal quality of the film is characterized. Figure 7 As shown, the α-Ga 2 O 3 The (10-10) crystal plane diffraction peak of the film has a high intensity and a narrow half-maximum full width (FWHM), and its FWHM value is 0.567°. The lower FWHM value indicates that the crystal has good orientation, less lattice distortion and defects, thus proving that the α-Ga 2 O 3 The film has good crystal quality.

[0046] Although the above embodiments have been described in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A method for epitaxial growth of α-Ga2O3 thin film by atmospheric pressure MOCVD based on tert-butyl alcohol precursor, characterized in that: The following steps are involved: (1) Cleaning the substrate and placing the cleaned substrate on a reaction chamber base of a metal organic chemical vapor deposition device; (2) Introduce nitrogen into the reaction chamber and adjust the pressure of the reaction chamber to 700-760 Torr; (3) Performing high temperature pretreatment on the substrate in the reaction chamber, the high temperature pretreatment conditions being 1000-1200°C for 15-30 minutes; (4) Cooling the substrate to 570-630°C, using triethylgallium as a gallium source precursor and tert-butyl alcohol as an oxygen source precursor, growing an α-Ga2O3 thin film sample on the substrate; (5) The α-Ga2O3 thin film sample is cooled to room temperature and nitrogen is introduced to obtain an α-Ga2O3 thin film.

2. The method according to claim 1, characterized in that: The substrate is an M-oriented (10-10) sapphire substrate.

3. The method according to claim 1, characterized in that: In the step (1), the method for cleaning the substrate comprises the following steps: S1: placing the substrate in ultrapure deionized water and performing ultrasonic cleaning; S2: pour out the ultrapure deionized water, add acetone, and perform ultrasonic cleaning; S3: Pour out the acetone, add anhydrous ethanol, and perform ultrasonic cleaning; S4: Pour out the anhydrous ethanol, add ultrapure deionized water and perform ultrasonic cleaning; S5: Pour out the ultrapure deionized water, take out the substrate and blow it dry with nitrogen.

4. The method according to claim 3, characterized in that: The ultrasonic cleaning time is 6 to 10 min.

5. The method according to claim 1, characterized in that: In the step (2), the pressure in the reaction chamber is adjusted to 760 Torr using a vacuum pump.

6. The method according to claim 1, characterized in that: In the step (3), the high temperature pretreatment is carried out at 1000° C. for 30 min.

7. The method according to claim 1, characterized in that: In the step (4), the substrate is cooled to 600° C. The specific process of growing the α-Ga2O3 thin film sample is as follows: after introducing tert-butanol and triethylgallium for 20 to 40 minutes, the introduction of triethylgallium is stopped, and the reaction chamber is purged in the tert-butanol atmosphere for 5 to 10 minutes, and the growth is completed.

8. The method according to claim 7, characterized in that: The flow rate of the triethylgallium is 120-180 sccm, and the flow rate of tert-butyl alcohol is 900-1100 sccm.

9. The method according to claim 8, characterized in that: The flow rate of triethylgallium is 150 sccm, and the flow rate of tert-butyl alcohol is 1000 sccm.

10. An α-Ga2O3 thin film prepared by the method according to any one of claims 1 to 9, characterized in that: The root mean square value of the surface roughness of the α-Ga2O3 film is 6.388-19.774 nm.

Images