Method for growing gallium oxide epitaxial film by mist chemical vapor deposition on a heterogeneous substrate

Abstract

The application discloses a method for growing gallium oxide epitaxial film by mist chemical vapor deposition on a heterogeneous substrate, which comprises substrate pretreatment, preparation of gallium-containing precursor solution, ultrasonic atomization delivery, low-temperature deposition and post-annealing crystallization. The substrate can be sapphire, silicon, silicon carbide or magnesium oxide, the concentration of the precursor is 0.01-0.5 mol / L, and the deposition temperature is 250-700 DEG C. The surface roughness of the film is less than 5 nm, and the electron mobility is greater than 100 cm 2 / V·s, and the film is preferentially oriented along the (200) plane. The method is simple in equipment and low in cost, is compatible with silicon process, and is suitable for preparation of large-size power devices and optoelectronic devices.

Description

Technical Field

[0001] This invention relates to the technical field of gallium oxide thin films, and in particular to a method for growing gallium oxide epitaxial thin films by fog chemical vapor deposition on heterogeneous substrates. Background Technology

[0002] Gallium oxide (Ga2O3) is an oxide semiconductor with a wide bandgap (approximately 4.8–4.9 eV) and is considered an important material for next-generation high-power and high-voltage electronic devices and deep ultraviolet photodetectors. β-Ga2O3 has attracted widespread attention in thin film and device research due to its relatively low lattice anisotropy and stable crystal structure in the (100) direction.

[0003] Currently, commonly used methods for preparing Ga2O3 thin films include molecular beam epitaxy (MBE), metal-organic chemical vapor deposition (MOCVD), pulsed laser deposition (PLD), and sputtering. However, these methods typically involve expensive equipment, high costs, and / or stringent substrate requirements. Mist-CVD, as a lower-cost liquid-phase precursor gas transport method that can be performed under ambient or near-ambient pressure conditions, has made significant progress in oxide thin film growth in recent years. However, challenges remain in achieving high-quality epitaxial growth, suppressing interface defects, and controlling strain. In particular, obtaining uniform, dense Ga2O3 epitaxial films with excellent lattice orientation on heterogeneous substrates (such as silicon, sapphire, and silicon carbide) still requires optimization of process parameters.

[0004] Therefore, there is an urgent need for a fog chemical vapor deposition method suitable for heterogeneous substrates that can obtain Ga2O3 epitaxial thin films with high crystallinity and low defect density to meet the needs of device fabrication. Summary of the Invention

[0005] This application provides a method for growing gallium oxide epitaxial films on heterogeneous substrates, comprising the following steps: Step S1. Perform surface pretreatment on the heterogeneous substrate; Step S2. Prepare a solution containing gallium precursor; Step S3. The precursor solution is atomized and then transported to the reaction chamber with the carrier gas; Step S4. Under set temperature and atmosphere conditions, the atomized precursor is reacted and deposited on the surface of the heterogeneous substrate to form a gallium oxide epitaxial film; Step S5. Perform post-annealing on the gallium oxide epitaxial film to improve crystallinity; The deposition process is a fog chemical vapor deposition method, and the heterogeneous substrate is selected from at least one of sapphire, silicon carbide, silicon or magnesium oxide.

[0006] In a preferred embodiment of a method for growing gallium oxide epitaxial thin films on a heterogeneous substrate, the gallium-containing precursor is one or more of gallium nitrate, gallium acetate, or gallium acetylacetonate, and the concentration of the precursor solution is 0.01 mol / L to 0.5 mol / L.

[0007] As a preferred embodiment of a method for growing gallium oxide epitaxial thin films on a heterogeneous substrate, the precursor solution further contains a complexing agent or a surfactant, wherein the complexing agent is selected from ethanolamine, ethylene glycol, ammonia, or a combination thereof, and the content is 0 to 10 wt% of the precursor mass.

[0008] In a preferred embodiment of a method for growing gallium oxide epitaxial thin films on a heterogeneous substrate, the atomization step is performed using an ultrasonic atomizer, the ultrasonic frequency is 1.0 MHz to 3.0 MHz, the carrier gas is nitrogen, argon, or a mixture thereof with oxygen, and the carrier gas flow rate is 100 to 2000 sccm.

[0009] As a preferred technical solution for a method of growing gallium oxide epitaxial thin films on a heterogeneous substrate, the heterogeneous substrate is ultrasonically cleaned sequentially with acetone, ethanol and deionized water before deposition, and then annealed at 300-1000°C in a hydrogen or oxygen atmosphere to remove surface contamination.

[0010] In a preferred embodiment of a method for growing gallium oxide epitaxial thin films on a heterogeneous substrate, the deposition temperature is 250°C to 700°C, the reaction chamber pressure is 0.01 to 2 atm, and the deposition time is 10 min to 5 h.

[0011] In a preferred embodiment of a method for growing gallium oxide epitaxial thin films on a heterogeneous substrate, a buffer layer or seed layer of 1–50 nm thickness is pre-formed on the heterogeneous substrate. The buffer layer is selected from GaN, AlN, MgO or amorphous gallium oxide.

[0012] As a preferred embodiment of a method for growing gallium oxide epitaxial films on a heterogeneous substrate, the post-annealing process is carried out in an oxygen or air atmosphere at 400°C to 900°C for 30 to 120 minutes.

[0013] As a preferred method for growing gallium oxide epitaxial films on heterogeneous substrates, an alternating atmosphere of oxygen-rich and inert gases is periodically introduced during the deposition process to improve the quality of the epitaxial crystal.

[0014] In addition, this application provides a gallium oxide epitaxial film, which is prepared by the method described above, characterized in that the epitaxial film is a β-Ga2O3 phase, the surface roughness RMS is less than 5 nm, and the film is grown along the (200) crystal plane.

[0015] Beneficial effects This invention employs a combination of fog chemical vapor deposition (CVD) with low-temperature deposition (250–700°C), precise ultrasonic atomization transport, periodic oxygen-enriched / inert atmosphere control, and post-annealing crystallization processes to successfully grow high-crystallinity β-Ga₂O₃ epitaxial films on various heterogeneous substrates such as sapphire, silicon, silicon carbide, and magnesium oxide. The resulting films exhibit a surface roughness as low as 0.9 nm and an electron mobility as high as 10⁸.3 cm⁻¹. 2 / V·s, carrier concentration can be controlled at 10 16 ~10 17 cm -3 The crystallinity swing curve (FWHM) is only 0.22°, and the thin film is highly preferentially oriented along the (200) plane, significantly surpassing traditional MOCVD and PLD processes. The process temperature is low, and the equipment cost is only 1 / 5 to 1 / 10 of that of traditional vapor phase epitaxy. It is compatible with silicon-based CMOS processes, and the growth rate reaches 2.7 to 5.0 nm / min, making it suitable for large-scale production of 6-inch and larger sizes. The buffer layer / seed layer design effectively alleviates lattice mismatch (mismatch rate <5%) and eliminates cracking and peeling. Comparative experiments have confirmed that post-annealing is the key step to achieve crystallization and performance leap. The optical transmittance of the fabricated thin film is >93%, the breakdown field strength is >7 MV / cm, and the radiation resistance threshold is >10 Mrad. It is widely applicable to 6G RF power amplifiers, electric vehicle inverters, deep ultraviolet detectors, aerospace radiation-resistant electronics, and deep-sea high-temperature sensors, providing a complete technical solution for the industrialization of gallium oxide semiconductors that is efficient, low-cost, and environmentally friendly. Detailed Implementation

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0017] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0018] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0019] Example Example 1 Step S1: Surface pretreatment of heterogeneous substrate Single-crystal sapphire (Al2O3, c-plane orientation) with dimensions of 2 cm × 2 cm was selected as the heterostructure substrate. First, the substrate was ultrasonically cleaned sequentially in acetone, isopropanol, and deionized water for 10 minutes each to remove surface grease, particles, and organic residues. After cleaning, it was dried with high-purity nitrogen and then placed in a tube furnace. The temperature was increased to 300°C at a rate of 5°C / min under a hydrogen atmosphere (flow rate 500 sccm) and held for annealing for 30 minutes to remove surface hydroxyl groups and adsorbed water molecules, ultimately obtaining a clean and smooth sapphire surface, providing an ideal interface for subsequent epitaxial growth.

[0020] Step S2: Prepare gallium-containing precursor solution Weigh 0.257 g of gallium nitrate hydrate (Ga(NO3)3·xH2O, purity 99.99%) and dissolve it in 100 mL of deionized water to prepare a transparent precursor solution with a concentration of 0.01 mol / L. No complexing agent or surfactant is added in this example. Place the solution on a magnetic stirrer and stir at 600 rpm for 30 minutes until completely dissolved. Then filter it through a 0.22 μm polytetrafluoroethylene filter membrane to remove insoluble impurities and obtain a clear and stable precursor solution, which is stored in a sealed polypropylene bottle for later use.

[0021] Step S3: Atomize and deliver the precursor The prepared precursor solution is injected into the liquid chamber of the ultrasonic atomizer, and the atomizer operating frequency is set to 1.0MHz. The carrier gas is high-purity nitrogen (purity 99.999%), and the flow rate is controlled at 100 sccm. The ultrasonic waves break the solution into droplet mists with an average diameter of about 2-5μm. The droplets are uniformly transported to the inlet of the reaction chamber through a heated stainless steel pipe (the pipe wall temperature is 80℃ to prevent condensation) along with the carrier gas, ensuring that the precursor is stably transported to the substrate surface in the form of an aerosol.

[0022] Step S4: Forming gallium oxide thin film by fog chemical vapor deposition The pretreated sapphire substrate was placed on the quartz base of the reaction chamber, and a vacuum was drawn until the base pressure was < 5 × 10⁻⁶. - 3 After Torr, a carrier gas is introduced; the reaction chamber pressure is maintained at 0.01 atm, and the substrate temperature is heated to 250°C by a back infrared lamp; the deposition time is 10 minutes; the atomized precursor is pyrolyzed at low temperature, and the gallium salt reacts with trace amounts of water vapor in the environment to generate gallium oxide, which is deposited in situ on the substrate surface to form an initial thin film with a growth rate of about 5 nm / min.

[0023] Step S5: Post-annealing treatment to improve crystallinity After deposition, the sample and substrate were transferred to another annealing furnace and heated to 400°C at a rate of 10°C / min in air atmosphere, and held for annealing for 30 minutes. During annealing, oxygen filled oxygen vacancies, promoting grain reconstruction and grain boundary migration. After annealing, the sample was naturally cooled to room temperature to obtain a β-Ga2O3 epitaxial film with improved crystallinity.

[0024] Example 2 Step S1: Surface pretreatment of heterogeneous substrate A p-type single-crystal silicon (100) substrate with dimensions of 2 cm × 2 cm was selected. First, the wafer was ultrasonically cleaned for 15 minutes each in acetone, ethanol, and deionized water. Then, it was immersed in dilute hydrofluoric acid (HF:H2O = 1:50) for 30 seconds to remove the native oxide layer. After rinsing with deionized water, the wafer was dried with nitrogen. The cleaned silicon wafer was placed in a high-temperature tube furnace and annealed at 700°C for 60 minutes in an oxygen atmosphere (flow rate 300 sccm) to form a thermal oxide layer of about 2 nm thick and remove surface contaminants, providing a clean interface for seed layer deposition.

[0025] Step S1 Supplement: Pre-deposition of amorphous gallium oxide seed layer A 10 nm thick layer of amorphous gallium oxide (a-Ga2O3) was deposited on a silicon surface using radio frequency magnetron sputtering as a seed layer. The target material was a high-purity Ga2O3 ceramic target (99.99%), the sputtering power was 100 W, the working gas was argon (flow rate 20 sccm), the chamber pressure was 5 mTorr, and the substrate temperature was kept at room temperature. The deposition rate was approximately 0.1 nm / s, and the total time was 100 seconds. The seed layer can reduce lattice mismatch and induce subsequent preferential orientation growth of β-Ga2O3.

[0026] Step S2: Prepare gallium-containing precursor solution 4.74 g of gallium acetate (Ga(CH3COO)3) was weighed and dissolved in a mixed solvent of 50 mL deionized water and 50 mL anhydrous ethanol to prepare a precursor solution with a total concentration of 0.2 mol / L. 1.2 mL of ammonia (25 wt%) (equivalent to 5 wt% of the precursor mass) was added as a surfactant to adjust the pH to ≈8. The solution was magnetically stirred in a 50℃ water bath for 1 hour until completely dissolved. After standing for 30 minutes to remove bubbles, the solution was filtered to obtain a uniform and stable light blue precursor solution.

[0027] Step S3: Atomize and deliver the precursor The precursor solution was injected into an ultrasonic atomizer with an atomization frequency set to 2.0 MHz. The carrier gas was a mixture of argon and oxygen (volume ratio 4:1) with a total flow rate of 1000 sccm. The average size of the droplets generated by atomization was approximately 1–3 μm. To ensure oxygen participation in the reaction, an additional 100 sccm of pure oxygen was introduced at the inlet of the reaction chamber. The atomized jet was delivered into the reaction chamber through a transmission line preheated to 120°C to ensure that the precursor reached the substrate surface in the form of an active aerosol.

[0028] Step S4: Forming gallium oxide thin film by fog chemical vapor deposition The reaction chamber pressure was controlled at 1 atm, the substrate temperature was stabilized at 500℃, and the total deposition time was 2 hours. To improve crystal quality, periodic atmosphere control was adopted: an oxygen-rich atmosphere (Ar:O2 = 3:2) was introduced for the first 60 minutes to promote the oxidation reaction; the atmosphere was switched to pure argon inert gas for the next 60 minutes to suppress excessively rapid oxidation; the gas composition was changed every 30 minutes; gallium acetate was pyrolyzed to generate Ga2O3, which was epitaxially grown on the seed layer, with a film thickness of about 320 nm.

[0029] Step S5: Post-annealing treatment to improve crystallinity After deposition, the sample was annealed at 650°C for 75 minutes in an oxygen atmosphere (flow rate 200 sccm) with a heating rate of 8°C / min. High-temperature oxygen annealing promoted the transformation of the amorphous phase to the β phase, repaired oxygen vacancies, and enhanced the preferred orientation of the (200) crystal plane. After annealing, the sample was furnace cooled to room temperature.

[0030] Example 3: Step S1: Surface pretreatment of heterogeneous substrate A 4H-SiC (0001) single crystal substrate with dimensions of 2 cm × 2 cm was selected. The substrate was ultrasonically cleaned sequentially in acetone, ethanol, and deionized water for 20 minutes each, and then immersed in RCA standard cleaning solution (NH4OH:H2O2:H2O = 1:1:5, 80℃, 10 min) to remove heavy metals and organic matter. After cleaning, the substrate was dried with nitrogen and placed in a high-temperature vacuum furnace. It was then annealed at 1000℃ for 90 minutes under a hydrogen atmosphere (flow rate 1000 sccm) to remove surface scratches and residual oxide layer, resulting in an atomically smooth SiC surface.

[0031] Additional step S1: Pre-deposit GaN buffer layer A 30 nm thick GaN buffer layer was grown on the SiC surface using pulsed laser deposition (PLD); a KrF excimer laser (248 nm) with an energy density of 2 J / cm² was used. 2 The target material was high-purity GaN, and the target-substrate distance was 5 cm. The substrate temperature during deposition was 700℃, and the nitrogen partial pressure was 1×10⁻⁶. -5Torr, pulse frequency 5 Hz, total pulse count 3000 times; GaN buffer layer has good lattice matching with SiC, which can effectively relieve stress between Ga2O3 and SiC.

[0032] Step S2: Prepare gallium-containing precursor solution 13.38 g of gallium acetylacetonate (Ga(C5H7O2)3) was weighed and dissolved in 100 mL of anhydrous ethanol to prepare a precursor solution with a concentration of 0.5 mol / L. 10.5 mL of ethylene glycol (equivalent to 10 wt% of the precursor mass) was added as a complexing agent to improve the stability of the solution. The solution was magnetically stirred in an oil bath at 60 °C for 2 hours until completely dissolved, and the solution was pale yellow. The solution was filtered through a 0.22 μm filter membrane to remove agglomerated particles and obtain a high-concentration, long-lasting stable precursor solution.

[0033] Step S3: Atomize and deliver the precursor The precursor solution is injected into a high-power ultrasonic nebulizer with a working frequency of 3.0 MHz; the carrier gas is a mixture of nitrogen and oxygen in equal volumes (N2:O2 = 1:1) with a total flow rate of 2000 sccm; high-frequency atomization generates submicron-sized droplets (< 1 μm), which are rapidly filled into the reaction chamber by the high-speed carrier gas; the transmission pipeline is heated to 150℃ to prevent gallium acetylacetonate from condensing and crystallizing on the pipe wall, ensuring efficient and uniform transport of the precursor.

[0034] Step S4: Forming gallium oxide thin film by fog chemical vapor deposition The reaction chamber pressure was maintained at 2 atm, the substrate temperature at 700℃, and the deposition lasted for 5 hours. The oxygen partial pressure in the carrier gas was high to ensure sufficient oxidation. Gallium acetylacetonate was completely pyrolyzed at high temperature to generate highly active Ga and O intermediates, and β-Ga2O3 was epitaxially grown on the GaN buffer layer. The growth rate was about 4 nm / min, the final film thickness was about 1.2 μm, and the surface exhibited a mirror-like gloss.

[0035] Step S5: Post-annealing treatment to improve crystallinity After deposition, the sample was annealed at 900°C for 120 minutes in a pure oxygen atmosphere (flow rate 500 sccm) with a heating rate of 10°C / min. High-temperature long-time annealing promoted grain growth and grain boundary annihilation, significantly improving crystallinity. After annealing, the sample was slowly cooled (3°C / min) to release stress.

[0036] Example 4: Step S1: Surface pretreatment of heterogeneous substrate A MgO (100) single crystal substrate with dimensions of 2 cm × 2 cm was selected. The substrate was ultrasonically cleaned in acetone, ethanol, and deionized water for 12 minutes each, followed by slight etching with dilute hydrochloric acid (1:10) for 10 seconds to remove the surface magnesium carbonate layer. After rinsing with deionized water, the substrate was dried with nitrogen and placed in a muffle furnace. It was then annealed at 600°C for 45 minutes in an oxygen atmosphere (flow rate 400 sccm) to restore the surface lattice integrity and remove adsorbed impurities.

[0037] Step S1 Supplement: Pre-deposition of AlN / Ga2O3 double buffer layer First, a 5 nm thick AlN layer was deposited by reactive sputtering (Al target, N2 / Ar = 1:1, power 80 W, room temperature), and then a 20 nm thick amorphous Ga2O3 layer was sputtered (Ga2O3 target, Ar atmosphere, power 100 W). The double buffer structure, combining the thermal stability of AlN and the chemical compatibility of Ga2O3, can significantly improve the epitaxial quality of β-Ga2O3.

[0038] Step S2: Prepare gallium-containing precursor solution Weigh 1.28 g of gallium nitrate and 2.37 g of gallium acetate (molar ratio 1:1), dissolve them together in 100 mL of deionized water to prepare a mixed precursor solution with a total concentration of 0.15 mol / L; add 0.6 mL of ethanolamine and 0.6 mL of ammonia (total complexing agent content 7wt%), and adjust the pH to ≈9; stir the solution at 40℃ for 2 hours, sonicate to remove bubbles for 20 minutes, and then filter to obtain a composite precursor solution with enhanced synergistic effect.

[0039] Step S3: Atomize and deliver the precursor The precursor solution is injected into the nebulizer at an ultrasonic frequency of 1.7 MHz; the carrier gas is high-purity argon with a flow rate of 800 sccm; the droplet size distribution is narrow, averaging about 2 μm; the temperature of the transmission pipeline is controlled at 100℃ to ensure that the solution does not evaporate or condense, and the mist is stably delivered to the central area of ​​the reaction chamber.

[0040] Step S4: Forming gallium oxide thin film by fog chemical vapor deposition The reaction chamber pressure was 0.5 atm, the substrate temperature was 450℃, and the deposition time was 3 hours. A periodic alternation of oxygen-rich and inert atmospheres was adopted: each cycle was 20 minutes. O2 was introduced at 300 sccm for the first 10 minutes (oxygen-rich period, to promote oxidation), and O2 was turned off for the next 10 minutes, with only Ar introduced (inert period, to control the growth rate). The alternating atmospheres effectively suppressed defects and formed a high-quality epitaxial layer with a film thickness of about 680 nm.

[0041] Step S5: Post-annealing treatment to improve crystallinity After deposition, the sample was annealed at 800℃ for 90 minutes in air atmosphere with a heating rate of 7℃ / min. During the annealing process, oxygen diffusion repaired lattice defects and promoted parallel growth of the (200) plane. After cooling, the sample surface was free of cracks.

[0042] Comparison Example Compare with Example 1 To verify the crucial role of post-annealing (step S5) in the crystallinity and surface roughness of gallium oxide epitaxial films, this comparative example was designed, omitting only step S5 (post-annealing) from Example 1, while all other steps (S1 to S4) and parameters were completely identical.

[0043]

[0044] As shown in the table above, as the process parameters were gradually optimized from low-end (Example 1) to high-end (Examples 3-4), the surface roughness RMS of the β-Ga2O3 epitaxial film continuously decreased from 4.8 nm to 0.9 nm, indicating that the synergistic effect of higher deposition temperature, concentration, carrier gas flow rate, and buffer layer / cycle atmosphere significantly promoted grain fusion and surface smoothing; the electron mobility simultaneously increased from 8.2 cm⁻¹. 2 / V·s has been significantly increased to 108.3 cm 2 / V·s (highest in Example 3), benefiting from increased crystallinity (FWHM decreased from 1.20° to 0.22°) and reduced defect density; while carrier concentration decreased from 5.2 × 10⁻⁶. 16 cm -3 Moderately increase to 3.5×10 17 cm -3 This reflects the controllable introduction of donor defects such as oxygen vacancies under high-temperature, oxygen-rich conditions. In Control Example 1 without post-annealing, the RMS surged to 12.7 nm, while the mobility dropped to <1.0 cm⁻¹. 2 However, the carrier concentration rose uncontrollably to 1.2 × 10⁻⁶ V·s due to a large number of disordered defects. 18 cm -3 This fully demonstrates that post-annealing is an indispensable step in achieving high-quality epitaxy and balancing surface and electrical properties.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for growing gallium oxide epitaxial thin films on heterogeneous substrates, characterized in that, Includes the following steps: Step S1. Perform surface pretreatment on the heterogeneous substrate; Step S2. Prepare a solution containing gallium precursor; Step S3. The precursor solution is atomized and then transported to the reaction chamber with the carrier gas; Step S4. Under set temperature and atmosphere conditions, the atomized precursor is reacted and deposited on the surface of the heterogeneous substrate to form a gallium oxide epitaxial film; Step S5. Perform post-annealing on the gallium oxide epitaxial film to improve crystallinity; The deposition process is a fog chemical vapor deposition method, and the heterogeneous substrate is selected from at least one of sapphire, silicon carbide, silicon or magnesium oxide.

2. The method according to claim 1, characterized in that, The gallium-containing precursor is one or more of gallium nitrate, gallium acetate, or gallium acetylacetonate, and the concentration of the precursor solution is 0.01 mol / L to 0.5 mol / L.

3. The method according to claim 1 or 2, characterized in that, The precursor solution further contains a complexing agent or surfactant, wherein the complexing agent is selected from ethanolamine, ethylene glycol, ammonia or a combination thereof, and the content is 0 to 10 wt% of the precursor mass.

4. The method according to claim 1, characterized in that, The atomization step is performed using an ultrasonic atomizer, with an ultrasonic frequency of 1.0 MHz to 3.0 MHz. The carrier gas is nitrogen, argon, or a mixture of nitrogen and oxygen, and the carrier gas flow rate is 100 to 2000 sccm.

5. The method according to claim 1, characterized in that, The heterogeneous substrate is ultrasonically cleaned sequentially with acetone, ethanol and deionized water before deposition, and then annealed at 300-1000°C in a hydrogen or oxygen atmosphere to remove surface contaminants.

6. The method according to claim 1, characterized in that, The deposition temperature is 250℃~700℃, the reaction chamber pressure is 0.01~2 atm, and the deposition time is 10 min~5 h.

7. The method according to claim 1, characterized in that, A buffer layer or seed layer with a thickness of 1 to 50 nm is pre-formed on the heterogeneous substrate. The buffer layer is selected from GaN, AlN, MgO or amorphous gallium oxide.

8. The method according to claim 1, characterized in that, The post-annealing process is carried out in an oxygen or air atmosphere at 400°C to 900°C for 30 to 120 minutes.

9. The method according to claim 1, characterized in that, During the deposition process, alternating atmospheres of oxygen-rich and inert gases are periodically introduced to improve the quality of epitaxial crystals.

10. A gallium oxide epitaxial thin film, prepared by the method according to any one of claims 1 to 9, characterized in that, The epitaxial film is a β-Ga2O3 phase with a surface roughness RMS of less than 5 nm, and the film is grown along the (200) crystal plane.

Images