Epitaxial growth method of gallium oxide thin film material

Abstract

The invention relates to an epitaxial growth method of a gallium oxide thin film material, which solves the technical problems of high thin film defect density, complex process and the like caused by random island nucleation and anisotropic etching in gallium oxide epitaxy. The method comprises the following steps: ultrasonically cleaning a substrate; annealing treatment; al atoms and In atoms are mixed and pre-deposited; and the pulse Al atoms assist in growing the gallium oxide thin film. On the basis of an Al atom and In atom mixed atomic layer, Al atoms are adopted as a pulse auxiliary source, two kinds of pulse growth cycle cycles are designed, and diffusion migration and uniform distribution of the Al atoms and In atoms on the surface are promoted. According to the method, the surface stability of the gallium oxide is enhanced, the decomposition and anisotropic etching of the gallium oxide are inhibited, preferential nucleation sites are provided for Ga and O atoms, non-ideal random island nucleation is reduced, and the quality of the gallium oxide film is remarkably improved. The gallium oxide thin film prepared by the method can be used for preparing high-voltage large-current power electronic devices and solar-blind ultraviolet photoelectric detectors.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor materials, and particularly relates to thin film material growth, and specifically to an epitaxial growth method of a gallium oxide thin film material. BACKGROUND

[0002] Gallium oxide (β-Ga2O3) with a monoclinic structure is a new type of ultra-wide bandgap semiconductor material, which has excellent characteristics such as an ultra-wide bandgap, a high critical breakdown field strength, and a high Baliga figure of merit, and thus attracts much attention in the next generation of high-power electronic devices. A good epitaxial process can not only reduce the defect density and improve the quality of β-Ga2O3 crystals, but also control the crystal orientation, thickness, structure, and effective doping of a β-Ga2O3 epitaxial layer in a large range. However, in the epitaxial growth of gallium oxide, whether it is homoepitaxial growth or heteroepitaxial growth, there are still non-ideal random island nucleation and spontaneous anisotropic etching phenomena. Random island nucleation is caused by the lack of preferential nucleation sites, while spontaneous anisotropic etching is caused by the reaction of Ga2O3 at high temperatures with Ga atoms to generate volatile Ga2O. In addition, the quality of the gallium oxide substrate needs to be improved, there is a large lattice mismatch and thermal mismatch between the hetero-substrate and β-Ga2O3, and the epitaxial growth process is not mature, etc., which makes the quality of the gallium oxide epitaxial film not high.

[0003] The patent document with the publication number CN118360667A discloses a gallium oxide epitaxial film and its preparation method and application, which cuts the gallium oxide crystal ingot at a specific angle and direction before epitaxial growth. Although this method can reduce the surface roughness of the epitaxial film, it also increases the process steps, resulting in an increase in process complexity. In addition, the precise control of the cutting process is also difficult.

[0004] The patent document with the publication number CN115029778A discloses a growth method of a gallium oxide epitaxial film, which uses triethylindium as a catalyst to homoepitaxially grow a β-Ga2O3 thin film on a gallium oxide (100) substrate by a pulse MOCVD method. Although this method can improve the crystalline quality of the gallium oxide epitaxial film, it limits the application range of the method to gallium oxide (100) substrates, and the effect on other substrate materials is not clear, so the application range is relatively narrow.

[0005] At present, gallium oxide film epitaxy has made some progress, but still faces many problems: on the one hand, due to the existence of random island nucleation, anisotropic etching, the quality of the substrate needs to be improved, the lattice and thermal mismatch problems are prominent, and the epitaxial growth process is not mature, which leads to the difficulty in improving the film quality; on the other hand, the existing part of the improvement method also has the obvious defects of high process complexity, narrow application range and the like. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art, and provide a gallium oxide film material epitaxial growth method to improve the quality of gallium oxide epitaxial film, and the process complexity is low and the application range is wide.

[0007] The present application is a gallium oxide film material epitaxial growth method, characterized in that it comprises the following steps:

[0008] Step 1: ultrasonic cleaning of the substrate: for the substrate used for epitaxial growth of gallium oxide film material, ultrasonic cleaning treatment is carried out with acid and organic solution;

[0009] Step 2: annealing treatment: using an annealing furnace to anneal the substrate after ultrasonic cleaning to obtain the annealed substrate;

[0010] Step 3: Al atom and In atom mixed pre-deposition: select gallium oxide epitaxial growth equipment according to the size of the substrate and the growth rate requirement, including molecular beam epitaxial growth equipment (MBE) and metal organic chemical vapor deposition epitaxial growth equipment (MOCVD); by accurately controlling the equivalent flow ratio of Al source and In source, Al atom and In atom are mixed and pre-deposited on the surface of the annealed substrate to form a mixed atomic layer of Al atom and In atom with a thickness of 1-3nm;

[0011] Step 4: pulse Al atom assisted growth of gallium oxide film: using the selected gallium oxide epitaxial growth equipment, adopting Al atom assisted growth method; setting two kinds of gallium oxide growth cycle periods assisted by pulse Al atom, accurately controlling the pulse duty cycle to be 1:3; controlling the equivalent flow of aluminum source so that the Al component in the gallium oxide film is less than 1%; periodically growing gallium oxide film on the deposited mixed atomic layer of Al atom and In atom to complete the epitaxial growth of gallium oxide film material with a thickness of 100-1000nm, and obtain a substrate with gallium oxide film.

[0012] The present application solves the technical problems of poor film quality caused by random island nucleation and anisotropic etching in gallium oxide epitaxial growth, and process complexity and narrow application range.

[0013] Compared with the prior art, the present application has the following advantages:

[0014] Enhanced Al atom diffusion and migration capabilities enable uniform distribution: In the pre-deposition of mixed Al and In atoms, this invention promotes Al atom diffusion and migration on the surface through the wetting effect of In atoms, thereby achieving a uniform distribution of nucleation sites. During gallium oxide film growth, this invention designs two gallium oxide growth cycles assisted by pulsed Al atoms. By providing sufficient diffusion time for Al atoms to avoid local enrichment, this further enhances the diffusion, migration, and uniform distribution of Al atoms on the surface. This invention provides targeted solutions from basic structure construction to growth process control, laying the foundation for optimizing the epitaxial quality of gallium oxide films using Al atoms.

[0015] Al atoms have a dual role in enhancing surface stability and providing preferred nucleation sites: In this invention, Al atoms are used as a pulse-assisted source to grow gallium oxide thin films. The uniformly distributed and appropriate amount of Al atoms can enhance the surface stability of gallium oxide, reduce its decomposition and anisotropic etching, thereby reducing the generation of defects. At the same time, these Al atoms can serve as preferred nucleation sites for Ga and O atoms, reducing non-ideal random island nucleation and promoting the improvement of gallium oxide film quality.

[0016] Wide range of engineering applications and low process complexity: The substrate material of this invention can be gallium oxide, sapphire, or magnesium oxide, so that the substrate with gallium oxide thin film can be used to prepare photodetectors, power diodes and transistor devices, with a wide range of applications; Since this invention can achieve high-quality gallium oxide thin film growth by using Al and In atoms mixed pre-deposition and pulsed Al atoms, the overall epitaxial growth process does not require additional processing and can be realized in the same epitaxial equipment, making the process simple. Attached Figure Description

[0017] Figure 1 This is a flowchart of the present invention;

[0018] Figure 2 This is a schematic diagram of the implementation process of the present invention;

[0019] Figure 3 This is a schematic diagram of the first pulse growth cycle timing of the present invention, wherein the oxygen source and gallium source are kept in a normally open state, and the aluminum source is controlled by a pulse, that is, it is turned on for 5 seconds and then turned off, and then turned on again after an interval of 10 seconds.

[0020] Figure 4 This is a schematic diagram of the second pulse growth cycle timing of the present invention, wherein the oxygen source and gallium source are kept in a normally open state, and the aluminum source is controlled by pulse, that is, it is turned on for 10 seconds and then turned off, and then turned on again after an interval of 20 seconds.

[0021] Figure 5 This is a surface morphology image of a gallium oxide thin film prepared using the method of this invention;

[0022] Figure 6 The image shows the surface morphology of a gallium oxide thin film not prepared using the method of this invention.

[0023] Figure 7 This is a comparison of the XRD rocking curves of gallium oxide films prepared using the method of this invention and those prepared without the method of this invention. Detailed Implementation

[0024] Example 1

[0025] Gallium oxide (GaO), with its unique material properties, has shown great application potential in the fabrication of high-voltage power devices and deep-ultraviolet optoelectronic devices, becoming a cutting-edge research area that domestic and international research institutions are vying to develop. As a crucial foundational step in device fabrication, the growth quality of GaO thin film epitaxy directly determines device performance. However, current GaO epitaxy still faces challenges such as poor growth quality and high complexity in some processes. To address these issues, this invention proposes an epitaxial growth method for GaO thin films with low surface roughness, high crystallinity, and low process complexity.

[0026] This invention relates to an epitaxial growth method for gallium oxide thin film materials. See [link to relevant documentation]. Figure 1 , Figure 1 This is a flowchart of the present invention, which includes the following steps:

[0027] Step 1: Ultrasonic cleaning of the substrate: For substrates used for epitaxial growth of gallium oxide thin films, ultrasonic cleaning is performed using acid and organic solutions.

[0028] Step 2 Annealing: The ultrasonically cleaned substrate is annealed using an annealing furnace to obtain an annealed substrate.

[0029] Step 3: Pre-deposition of Al and In atoms: Select gallium oxide epitaxial growth equipment based on substrate size and growth rate requirements, including molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) equipment; precisely control the equivalent flow ratio of Al source and In source through epitaxial growth equipment, mix and pre-deposit Al atoms and In atoms on the annealed substrate surface to form a mixed atomic layer of Al and In atoms with a thickness of 1-3 nm;

[0030] Step 4: Pulsed Al atom-assisted growth of gallium oxide thin film to obtain a substrate with gallium oxide film: Using the selected gallium oxide epitaxial growth equipment, an Al atom-assisted growth method is adopted; two gallium oxide growth cycle periods with pulsed Al atoms as assistance are set, and the pulse duty cycle is precisely controlled to be 1:3; the equivalent flow rate of the aluminum source is controlled so that the Al composition in the gallium oxide film is less than 1%; gallium oxide film is periodically grown on the mixed atomic layer of deposited Al atoms and In atoms to complete the epitaxial growth of gallium oxide film material with a thickness of 100-1000 nm, and a substrate with gallium oxide film is obtained.

[0031] To address the challenges of poor growth quality and high complexity in some processes in gallium oxide epitaxy, this invention offers the following solution: By controlling the amount and introduction method of the aluminum source, and combining this with the interaction between In and Al atoms, the diffusion and migration capabilities of Al atoms on the surface are enhanced, resulting in a uniform distribution. This lays the foundation for Al atoms to play a role in improving film quality. During the gallium oxide epitaxial growth process, Al atoms are used as a pulse-assisted source. A suitable and uniformly distributed amount of Al atoms has the dual effect of enhancing surface stability and providing preferential nucleation sites, effectively suppressing random island nucleation and anisotropic etching, thereby promoting film quality improvement. Furthermore, the entire epitaxial growth process is completed within the same epitaxial equipment, making the process simple and easy to implement.

[0032] This invention is an integrated technical solution that innovatively employs a mixed pre-deposition of Al and In atoms and pulsed Al atom-assisted growth of gallium oxide thin films. Specifically, during the mixed pre-deposition of Al and In atoms, the wetting effect of In atoms can specifically enhance the surface diffusion ability of Al atoms. During the gallium oxide film growth process, the two gallium oxide growth cycles assisted by pulsed Al atoms further promote the uniform distribution of Al atoms. The two work synergistically to create better conditions for Al atoms to exert their effects. Based on this innovative design, an appropriate amount and uniform distribution of Al atoms not only enhances the surface stability of gallium oxide, suppresses decomposition and anisotropic etching to reduce defects, but also serves as a preferential nucleation site for Ga and O atoms, effectively reducing non-ideal random island nucleation, ultimately achieving a significant improvement in the quality of gallium oxide thin films.

[0033] Example 2: The epitaxial growth method for gallium oxide thin film material is the same as in Example 1. The substrate described in step 1 of this invention can be gallium oxide, sapphire, or magnesium oxide, etc., as the substrate material. When gallium oxide is used as the substrate, the sample formed by epitaxial growth of gallium oxide thin film is particularly suitable for fabricating power electronic devices, specifically diodes and transistors. Its core advantage lies in meeting the stringent requirements of high-voltage, high-power electronic systems. When the substrate is sapphire or magnesium oxide, the sample obtained after epitaxial growth of gallium oxide thin film can be specifically used to fabricate solar-blind ultraviolet photodetectors, possessing high sensitivity response characteristics to deep ultraviolet light signals, accurately capturing weak light signals in this band, and adapting to special ultraviolet detection scenarios. When silicon carbide is used as the substrate, due to its high thermal conductivity, the gallium oxide thin film prepared in this invention has excellent heat dissipation performance, suitable for high-power device applications in high-temperature environments. When silicon is used as the substrate, thanks to the low cost, large size, and mature processing technology of silicon material, the prepared gallium oxide thin film is more easily integrated and compatible with existing silicon-based circuits, suitable for the development and application of large-scale optoelectronic integrated devices.

[0034] Example 3: The epitaxial growth method for gallium oxide thin film material is the same as in Examples 1-2. The ultrasonic cleaning of the substrate described in step 1 of this invention specifically applies to the substrate used for epitaxial growth of gallium oxide thin film material. Ultrasonic cleaning is performed using acid and an organic solution, and includes the following steps:

[0035] 1.1 Acid solution ultrasonic cleaning: Immerse the substrate in HF solution and place it in a water bath. First, perform low-frequency ultrasonic treatment for 3-5 minutes, then switch to high-frequency ultrasonic treatment for 3-5 minutes, and then rinse with deionized water for 3-5 minutes to obtain an acid solution ultrasonically cleaned substrate.

[0036] 1.2 Ultrasonic cleaning with organic solutions:

[0037] 1.2.1 Place the substrate that has been ultrasonically cleaned with acid solution in acetone solution and place the whole substrate in a water bath. First, treat it with low-frequency ultrasound for 3 to 5 minutes, and then switch to high-frequency ultrasound for 3 to 5 minutes to obtain a substrate that has been ultrasonically cleaned with acetone solution.

[0038] 1.2.2 Place the substrate that has been ultrasonically cleaned with acetone solution into isopropanol solution, and then place the whole substrate in a water bath for low-frequency ultrasonic treatment for 3 to 5 minutes. After that, rinse with deionized water for 3 to 5 minutes, and finally dry with a nitrogen gun to complete the ultrasonic cleaning of the substrate.

[0039] The stepwise treatment with acid and organic solutions targets and removes inorganic impurities and organic contaminants from the substrate surface, respectively. The alternating use of low-frequency and high-frequency ultrasound leverages the strong impact of low-frequency ultrasound to remove stubborn large particles, while the fine vibration of high-frequency ultrasound removes minute contaminants. This synergistic approach ensures more thorough cleaning, providing a cleaner substrate surface for subsequent epitaxial growth.

[0040] Example 4: The epitaxial growth method of gallium oxide thin film material is the same as that in Examples 1-3. The annealing treatment described in step 2 of this invention is to anneal the substrate after ultrasonic cleaning using an annealing furnace. The annealing conditions are: in a nitrogen atmosphere, the annealing furnace temperature is set to 800-1100℃, and the annealing time is 1-2 hours.

[0041] A nitrogen atmosphere can effectively prevent secondary contamination of the substrate surface, while precise temperature and time control can further remove trace adsorbed impurities remaining on the surface, promote atomic rearrangement on the substrate surface, optimize surface flatness and crystal structure integrity, and provide a more stable interface environment for subsequent epitaxial growth of thin films.

[0042] Example 5: The epitaxial growth method of gallium oxide thin film material is the same as in Examples 1-4. The mixed pre-deposition of Al atoms and In atoms in step 3 of this invention is achieved by the following steps:

[0043] 3.1 Select epitaxial equipment based on substrate size and growth rate requirements: For epitaxial growth with small substrate size and requiring atomically precise control of film thickness, MBE equipment is selected. For epitaxial growth with large substrate size and requiring high growth rate, MOCVD equipment is selected.

[0044] 3.2 Substrate Placement and Equipment Epitaxial Process Conditions: The annealed substrate is placed into the selected epitaxial growth equipment, and a mechanical pump is used to fill the equipment pipes and growth chamber to reduce environmental impurities. Epitaxial process conditions for mixed Al and In atom pre-deposition are set according to the selected equipment type, with the equivalent flow ratio of Al source to In source controlled at 1:1 to 1:3 to ensure effective wetting of Al atoms by In atoms.

[0045] 3.3 Growth of a mixed atomic layer of Al and In atoms: Under the set epitaxial process conditions, Al and In atoms are simultaneously deposited on the surface of the substrate after annealing in the chamber. The wetting effect of In atoms promotes the diffusion, migration and uniform distribution of Al atoms on the surface, forming a mixed pre-deposited atomic layer of Al and In atoms with a thickness of 1-3 nm and uniform distribution.

[0046] MBE equipment boasts an ultra-high vacuum environment and atomic-level precision control, enabling precise control over composition and thickness. However, this equipment typically only allows for epitaxial growth on small-sized substrates, making it suitable for laboratory research and development and high-end device fabrication where extremely high film quality is required. MOCVD, on the other hand, is characterized by high growth rates, excellent large-area epitaxial uniformity, and strong process compatibility, making it more suitable for large-scale industrial production and efficiently meeting batch preparation needs. Both can be flexibly selected based on the application scenario, and both can achieve controllable deposition of 1–3 nm mixed atomic layers through precise regulation, laying the foundation for subsequent epitaxial growth.

[0047] Example 6 describes the epitaxial growth method of gallium oxide thin film material as described in Examples 1-5. Step 3.2 of this invention, which involves setting the epitaxial equipment process conditions, includes:

[0048] 3.2.1 When using the MBE equipment, the main parameters to be set are: growth temperature of 600–800℃ and chamber pressure of 1×10⁻⁶. -5 ~2×10 -5 Torr, setting the equivalent pressure of the aluminum beam to 2×10 -9 ~6×10 -9 Torr, the equivalent pressure of the indium beam is 2 × 10⁻⁶ -9 ~6×10 -9 Torr, the equivalent pressure ratio of the aluminum beam to the indium beam is 1:1 to 1:3.

[0049] 3.2.2 When using MOCVD equipment, the main parameters to be set are: reaction chamber temperature of 700-900℃, chamber pressure of 40-100 mbarr, argon as carrier gas, trimethylaluminum as aluminum source, trimethylindium as indium source, and the flow rate of trimethylaluminum of 2-6 sccm, the flow rate of trimethylindium of 2-6 sccm, and the flow rate ratio of trimethylaluminum to trimethylindium of 1:1-1:3.

[0050] In the preparation process of this invention, only one type of equipment is used: either an MBE device or an MOCVD device, each requiring its own corresponding process conditions. The single device's full involvement throughout the process ensures optimal performance of the mixed atomic layers through parameter matching, avoids equipment switching issues, simplifies the process, and facilitates targeted optimization.

[0051] This invention controls the equivalent flow ratio of Al source to In source at 1:1 to 1:3, which can ensure the effectiveness of In atoms wetting Al atoms, promote the diffusion and uniform distribution of Al atoms on the surface, and provide smooth, stable interface conditions with preferential nucleation sites for subsequent gallium oxide film growth.

[0052] Example 7: The epitaxial growth method of gallium oxide thin film material is the same as in Examples 1-6. The growth of a mixed atomic layer of Al atoms and In atoms described in step 3.3 of this invention includes:

[0053] 3.3.1 Deposition process using MBE equipment: The beam baffles for both the aluminum and indium beams in the equipment are activated, allowing both beams to act simultaneously on the substrate surface within the chamber. The wetting effect of In atoms promotes the diffusion, migration, and uniform distribution of Al atoms on the surface. This invention utilizes in-situ monitoring to measure the growth rate in real time and adjusts the beam baffle activation time accordingly, depositing a mixed atomic layer of Al and In atoms with a thickness of 1–3 nm on the annealed substrate surface within the chamber.

[0054] 3.3.2 Deposition process using MOCVD equipment: The control valves for the aluminum and indium sources inside the equipment are opened, allowing them to enter the reaction chamber along with the carrier gas. In atoms and Al atoms are co-deposited on the substrate surface within the chamber. In atoms promote the migration and diffusion of Al atoms, resulting in a uniform distribution of Al atoms on the surface and preventing random island-like nucleation. This invention monitors changes in sample reflectivity in real time to control the growth rate and adjusts the valve opening time accordingly, depositing a uniform mixed atomic layer of Al and In atoms with a thickness of 1–3 nm on the annealed substrate surface.

[0055] In this invention, MBE (Metal-Based Beam Evolution) controls the growth rate and time by adjusting the beam baffle and combining it with in-situ monitoring, while MOCVD (Metal-Based Chemical Valves) achieves precise control of the growth process by regulating the source valve and monitoring reflectivity changes. Both methods can precisely control the thickness of the mixed atomic layer from 1 to 3 nm, ensuring the controllability of the deposition process and the uniformity of the final atomic layer. Furthermore, controlling the thickness of the mixed atomic layer of Al and In atoms to 1–3 nm provides uniform nucleation sites, suppresses non-ideal random island nucleation to ensure continuous layered growth of gallium oxide, and its ultrathin characteristics suppress Al and In atom segregation, avoiding interference with the subsequent gallium oxide lattice arrangement. This lays the foundation for optimizing the epitaxial quality of gallium oxide films using Al atoms.

[0056] In this embodiment, the thickness of the mixed atomic layer of Al and In atoms is precisely controlled according to the type of annealed substrate in the cavity: if the substrate material is gallium oxide, since there is no lattice mismatch or thermal mismatch between the gallium oxide film and the substrate, the thickness of the mixed atomic layer is controlled to 1 nm, so as to optimize the film quality and avoid introducing additional lattice distortion; if the substrate material is magnesium oxide or sapphire, since there is lattice mismatch and thermal mismatch between the gallium oxide film and the substrate, the thickness of the mixed atomic layer is controlled to 3 nm, so as to give full play to the optimization performance of the layer.

[0057] Example 8: The epitaxial growth method of gallium oxide thin film material is the same as in Examples 1-7. The pulsed Al atom-assisted growth of gallium oxide thin film described in step 4 of this invention includes the following steps:

[0058] 4.1 Constructing an assisted growth method: Based on the epitaxial equipment, Al atoms are used as a pulse auxiliary source to participate in the epitaxial growth of gallium oxide. The composition of Al atoms in the gallium oxide film is less than 1% to play an auxiliary optimization role.

[0059] 4.2 Two Gallium Oxide Growth Cycles Assisted by Pulsed Al Atoms: Based on the optimized effect of pulsed Al atom assistance in gallium oxide thin film epitaxy, this invention establishes two pulsed growth cycles. The common feature of both cycles is that the oxygen and gallium sources are continuously on, and the aluminum source is pulsed with a pulse duty cycle of 1:3. The first pulsed growth cycle involves turning off the aluminum source after 5 seconds, then restarting it after a 10-second interval, suitable for preparing gallium oxide thin films with a thickness less than 500 nm. The second pulsed growth cycle involves turning off the aluminum source after 10 seconds, then restarting it after a 20-second interval, suitable for preparing gallium oxide thin films with a thickness greater than 500 nm.

[0060] 4.3 Setting gallium oxide thin film deposition process conditions: Using the epitaxial equipment described above for the mixed Al and In atom pre-deposition process, maintain a high vacuum environment in the chamber. Set the gallium oxide thin film deposition process parameters according to the type of epitaxial equipment. The equivalent flow rate of the aluminum source should ensure that the Al content in the gallium oxide thin film is less than 1%.

[0061] 4.4 Growth of gallium oxide thin films: Select the first or second pulse growth cycle, and under the set gallium oxide thin film deposition process conditions, grow gallium oxide thin films with a thickness of 100-1000 nm.

[0062] In this invention, the process of pulsed Al atom-assisted growth of gallium oxide thin films utilizes the same epitaxial equipment used for the mixed pre-deposition of Al and In atoms, maintaining a high vacuum environment to avoid contamination and ensuring process continuity and stability. This invention uses Al atoms as the pulsed auxiliary source, setting the aluminum source to a pulsed switch with a pulse duty cycle of 1:3. This mode provides Al atoms with more diffusion time to avoid local enrichment caused by continuous supply, enhancing the diffusion, migration, and uniform distribution of Al atoms on the surface. The appropriate amount and uniform distribution of Al atoms in this invention, on the one hand, enhances the surface stability of gallium oxide, reduces its decomposition and anisotropic etching, thereby reducing defect generation; on the other hand, it also serves as a preferential nucleation site for Ga and O atoms, reducing non-ideal random island nucleation and promoting improved gallium oxide thin film quality.

[0063] The first pulse growth cycle of this invention features a short cycle time and a high Al atom supply frequency, enabling more precise control of Al doping. The high-frequency pulse cycle allows for a more uniform distribution of Al atoms at the growth interface, making it particularly suitable for applications requiring extremely high Al distribution uniformity, such as the fabrication of thin gallium oxide films or devices sensitive to lattice integrity. This maximizes the suppression of non-ideal island nucleation and ensures the flatness of the epitaxial layer.

[0064] The second pulse growth cycle pattern of this invention has a longer cycle time and a relatively larger supply of Al atoms per cycle, which can appropriately improve growth efficiency while ensuring controllable Al composition. Its advantage lies in its suitability for the preparation of thicker gallium oxide films. By reducing the pulse switching frequency through a relatively long cycle, it balances the uniformity of Al distribution while reducing growth fluctuations caused by high-frequency modulation, making it more suitable for the needs of large-scale, high-efficiency film preparation.

[0065] Example 9: The epitaxial growth method of gallium oxide thin film material is the same as in Examples 1-8. The gallium oxide thin film deposition process conditions described in step 4.3 of this invention include:

[0066] 4.3.1 When using MBE equipment: Maintain a high vacuum environment in the chamber, set the substrate temperature to 600–800°C, and the chamber pressure to 1 × 10⁻⁶. -5 ~2×10 -5 Torr, oxygen plasma power is 250-300W, aluminum beam equivalent pressure is 2×10 -9 ~6×10 -9 Torr, the gallium beam equivalent pressure is 1×10⁻⁶ -7 ~2×10 -7 Torr is used to ensure that the Al component in the grown gallium oxide film is less than 1%.

[0067] 4.3.2 When using MOCVD equipment: Maintain a high vacuum environment in the chamber, set the reaction chamber temperature to 700-900℃, the pressure to 40-100mbar, use argon as the carrier gas, trimethylaluminum as the aluminum source, trimethylgallium as the gallium source, and oxygen as the oxygen source. The flow rate of trimethylaluminum is 2-6 sccm, and the molar flow rate ratio of trimethylgallium to oxygen is 1:5000-1:200, so that the Al component in the grown gallium oxide film is less than 1%.

[0068] This invention controls the Al content in gallium oxide thin films to below 1% by precisely optimizing the source ratio and environmental parameters. This fully leverages the dual role of Al atoms in enhancing surface stability and providing preferential nucleation sites, while effectively avoiding negative impacts: reducing lattice distortion caused by Al atoms occupying Ga atom sites and maintaining the high crystallinity of gallium oxide thin films; and simultaneously reducing interference with the intrinsic properties of gallium oxide, such as its wide bandgap and high breakdown field strength, thus ensuring the fabrication of high-performance devices.

[0069] Example 10: The epitaxial growth method of gallium oxide thin film material is the same as in Examples 1-9. The gallium oxide thin film growth described in step 4.4 of this invention includes:

[0070] 4.4.1 Gallium oxide thin film growth process using MBE equipment: The gallium beam baffle and oxygen plasma are turned on to continuously act on the sample surface; the aluminum beam is controlled in pulse mode with a pulse duty cycle of 1:3. The first pulse growth cycle is set to turn on for 5 seconds, then off, and wait for 10 seconds before turning on again. The second pulse growth cycle is set to turn on for 10 seconds, then off, and wait for 20 seconds before turning on again. One of the pulse growth cycle patterns is used for periodic growth. The growth rate is measured in real time through in-situ monitoring, and the total growth time is adjusted accordingly to control the epitaxial film thickness between 100 and 1000 nm, thus completing the pulsed Al atom-assisted growth of gallium oxide thin film.

[0071] 4.4.2 Gallium oxide thin film growth process using MOCVD equipment: The gallium source and oxygen are continuously introduced into the growth chamber. The aluminum source is controlled by pulsed on / off switching, with a pulse duty cycle of 1:3. When using the first pulse growth cycle, it is specifically set to be on for 5 seconds, then off, and then on again after a 10-second wait. When using the second pulse growth cycle, it is set to be on for 10 seconds, then off, and then on again after a 20-second wait. The specific implementation process uses one of the pulse growth cycle patterns for periodic growth. The growth rate is monitored in real time by controlling the change in sample reflectivity, and the valve opening time is adjusted accordingly to control the epitaxial film thickness between 100 and 1000 nm, completing the pulsed Al atom-assisted growth of gallium oxide thin films.

[0072] This invention optimizes crystal quality and suppresses defects through the periodic action of Al atoms, while ensuring the continuity and stability of growth by continuously supplying Ga and O atoms. This allows pulse assistance and growth efficiency to work together effectively, comprehensively improving the quality and growth performance of gallium oxide epitaxy.

[0073] In this embodiment, the thickness of the gallium oxide epitaxial film is controlled according to the substrate type and application scenario: If the substrate is gallium oxide and it is used to fabricate a high-voltage vertical diode device, the gallium oxide film thickness can be controlled to 1000 nm or more. If the substrate is gallium oxide and it is used to fabricate a high-voltage, low-on-resistance lateral transistor device, the gallium oxide film thickness can be controlled to 200–400 nm. If the substrate is sapphire or magnesium oxide and it is used to fabricate a solar-blind ultraviolet photodetector device, the gallium oxide film thickness can be controlled to 100–500 nm.

[0074] Example 11: The epitaxial growth method of the gallium oxide thin film material is the same as in Examples 1-10. The gallium oxide thin films prepared by the above examples are suitable for the following application scenarios:

[0075] 11.1 Application in Power Electronic Device Fabrication: When the substrate is gallium oxide, the gallium oxide thin film prepared by epitaxial growth according to this invention possesses excellent crystal quality and is suitable for fabricating high-voltage, high-current power electronic devices, specifically for manufacturing diodes and transistors with low on-resistance and low power loss. Compared with thin films prepared by conventional processes, its power conversion efficiency is significantly improved. This characteristic provides strong support for the efficient and stable operation of high-voltage, high-power electronic systems.

[0076] 11.2 Applications to Optoelectronic Device Fabrication: When the substrate is sapphire or magnesium oxide, the gallium oxide thin film prepared by epitaxial growth according to this invention achieves uniform grain size, precise control of defect density, and low surface roughness, making it specifically suitable for fabricating solar-blind ultraviolet photodetectors. Compared with gallium oxide thin films prepared by traditional processes, its detection performance is significantly improved, especially its higher sensitivity response to light signals in the deep ultraviolet band. This characteristic provides strong support for the accurate capture of weak light signals in special ultraviolet detection scenarios.

[0077] The following are some more specific examples, which will be explained in conjunction with the technical solution and effects of the present invention.

[0078] Example 12: The epitaxial growth method of gallium oxide thin film material is the same as in Examples 1-11, see [link to example]. Figure 2 , Figure 2 This is a schematic diagram of the implementation process of the present invention. This embodiment uses an MBE epitaxial growth apparatus with sapphire as the substrate material. First, a mixed atomic layer of Al and In atoms with a thickness of 3 nm is grown. Then, a first gallium oxide growth cycle pattern assisted by pulsed Al atoms is selected. Under appropriate process conditions, a gallium oxide thin film with a thickness of 100 nm is finally grown. The implementation includes the following steps:

[0079] Step 1: Select a substrate and perform ultrasonic cleaning.

[0080] Sapphire was selected as the substrate material. The sapphire substrate was immersed in HF solution and placed in a water bath. It was first treated with low-frequency ultrasound for 5 minutes, then switched to high-frequency ultrasound for 5 minutes, and then rinsed with deionized water for 5 minutes to obtain a substrate that had been ultrasonically cleaned with acid solution.

[0081] The substrate that has been ultrasonically cleaned with acid solution is placed in acetone solution and then placed in a water bath. It is first treated with low-frequency ultrasound for 5 minutes, and then switched to high-frequency ultrasound for 5 minutes to obtain a substrate ultrasonically cleaned with acetone solution.

[0082] The substrate, which has been ultrasonically cleaned with acetone solution, is placed in isopropanol solution and then placed in a water bath. It is treated with low-frequency ultrasound for 5 minutes, then rinsed with deionized water for 5 minutes, and finally dried with a nitrogen gun to complete the ultrasonic cleaning of the substrate.

[0083] Step two, annealing.

[0084] The cleaned substrate material is placed in an annealing furnace, and high-purity nitrogen gas is introduced into the furnace.

[0085] The annealing temperature was set to 800℃ and annealed for 2 hours to further remove substrate impurities.

[0086] Step 3: Using an MBE epitaxial growth device, a 3nm layer of Al and In atoms is pre-deposited on the annealed substrate surface.

[0087] MBE epitaxial growth equipment was selected, and the annealed substrate was placed in the MBE reaction chamber. A mechanical pump was used to fill the pipes and chamber to reduce impurities introduced from the environment.

[0088] The growth temperature was set at 800℃, and the chamber pressure was set at 2×10⁻⁶. -5 Torr, the equivalent pressure of the aluminum beam is 2 × 10⁻⁶ -9 Torr, the equivalent pressure of the indium beam is 6 × 10⁻⁶ -9 Torr, the equivalent pressure ratio of the aluminum beam to the indium beam is 1:3.

[0089] After the chamber environment stabilizes, the beam baffles for the aluminum and indium beams are opened, allowing both beams to act on the substrate surface within the chamber. The growth rate is measured in real time using in-situ monitoring, and the beam baffle opening time is adjusted accordingly to deposit a 3nm thick mixed atomic layer of Al and In atoms on the annealed substrate surface within the chamber.

[0090] Step four: Using the first gallium oxide growth cycle pattern assisted by pulsed Al atoms, a gallium oxide thin film with a thickness of 100 nm is grown on top of a mixed atomic layer of Al and In atoms.

[0091] The sample with the deposited mixed atomic layer of Al and In atoms was placed inside the MBE reaction chamber, maintaining a high vacuum environment. The substrate temperature was set to 800°C and the chamber pressure to 1×10⁻⁶. -5 Torr, oxygen plasma power is 300W, aluminum beam equivalent pressure is 6×10 -9 Torr, the gallium beam equivalent pressure is 2×10⁻⁶. -7 Torr.

[0092] After the chamber conditions stabilized, the gallium beam baffle and oxygen plasma were activated to continuously act on the sample surface. The aluminum beam was controlled in pulse mode, specifically set to a pulse growth cycle of 5 seconds on, 10 seconds off, and then restarting. (See also...) Figure 3 This diagram illustrates the timing sequence of the oxygen, gallium, and aluminum sources in this embodiment, specifically the timing sequence of the first pulse growth cycle of the present invention: the oxygen and gallium sources are continuously on, while the aluminum source is controlled according to the aforementioned pulse mode. The above-described periodic growth process is repeated, and the growth rate is measured in real-time through in-situ monitoring. Based on this, the total growth time is adjusted to control the epitaxial film thickness at 100 nm, thus completing the pulsed Al atom-assisted growth of gallium oxide thin films.

[0093] In this embodiment, sapphire was used as the substrate material to fabricate a gallium oxide thin film with a thickness of 100 nm. This film exhibits outstanding advantages in the fabrication of solar-blind ultraviolet photodetectors: firstly, it has high sensitivity to optical signals in the 200–280 nm solar-blind ultraviolet band; secondly, it has low dark current and fast response speed, enabling precise capture of weak solar-blind ultraviolet radiation. Therefore, this film is highly suitable for the fabrication of the core layer of solar-blind ultraviolet photodetectors, providing a high-quality material foundation for the development of high-performance detectors.

[0094] Example 13: The epitaxial growth method for gallium oxide thin film material is the same as in Examples 1-12. This example uses an MOCVD epitaxial growth device with gallium oxide as the substrate material. First, a mixed atomic layer of Al and In atoms with a thickness of 1 nm is grown. Then, a second gallium oxide growth cycle pattern assisted by pulsed Al atoms is selected. Under the corresponding process conditions, a gallium oxide thin film with a thickness of 1000 nm is finally grown. The process includes the following steps:

[0095] Step 1: Select a substrate and perform ultrasonic cleaning.

[0096] Gallium oxide was selected as the substrate material. The gallium oxide substrate was immersed in HF solution and placed in a water bath. It was first treated with low-frequency ultrasound for 3 minutes, then switched to high-frequency ultrasound for 3 minutes, and then rinsed with deionized water for 3 minutes to obtain a substrate that had been ultrasonically cleaned with acid solution.

[0097] The substrate that has been ultrasonically cleaned with acid solution is placed in acetone solution and then placed in a water bath. It is first treated with low-frequency ultrasound for 3 minutes, and then switched to high-frequency ultrasound for 3 minutes to obtain a substrate ultrasonically cleaned with acetone solution.

[0098] The substrate, which has been ultrasonically cleaned with acetone solution, is placed in isopropanol solution and then placed in a water bath. It is treated with low-frequency ultrasound for 3 minutes, then rinsed with deionized water for 3 minutes, and finally dried with a nitrogen gun to complete the ultrasonic cleaning of the substrate.

[0099] Step 2, annealing.

[0100] The cleaned substrate material is placed in an annealing furnace, and high-purity nitrogen gas is introduced into the furnace.

[0101] The annealing temperature was set to 1100℃ and annealed for 1 hour to further remove substrate impurities.

[0102] Step 3: Using MOCVD epitaxial growth equipment, a 1 nm layer of Al and In atoms is pre-deposited on the surface of the annealed substrate.

[0103] MOCVD epitaxial growth equipment was selected, and the annealed substrate was placed in the MOCVD reaction chamber. Mechanical pumps were used to fill the pipes and chamber to reduce environmental impurities.

[0104] The reaction chamber temperature was set at 700℃ and the pressure at 100mbar. Argon was used as the carrier gas, trimethylaluminum as the aluminum source and trimethylindium as the indium source. The flow rates of trimethylaluminum and trimethylindium were set at 2 sccm and 2 sccm respectively, with a flow ratio of 1:1.

[0105] After the chamber environment stabilizes, the control valves for the aluminum and indium sources are opened, allowing them to enter the reaction chamber along with the carrier gas, thus depositing In atoms and Al atoms together on the substrate surface. The growth rate is monitored in real time by tracking changes in sample reflectivity, and the valve opening time is adjusted accordingly to deposit a mixed atomic layer of Al and In atoms with a thickness of 1 nm on the annealed substrate surface.

[0106] Step 4: Select the second gallium oxide growth cycle pattern assisted by pulsed Al atoms to grow a gallium oxide thin film with a thickness of 1000 nm on top of a mixed atomic layer of Al and In atoms.

[0107] The sample with the deposited mixed atomic layer of Al and In atoms was placed in the MOCVD reaction chamber to maintain a high vacuum environment. The reaction chamber temperature was set to 900℃ and the pressure to 40mbar. Argon was used as the carrier gas, trimethylaluminum as the aluminum source, trimethylgallium as the gallium source, and oxygen as the oxygen source. The flow rate of trimethylaluminum was 6 sccm, and the molar flow rate ratio of trimethylgallium to oxygen was 1:5000.

[0108] Once the chamber conditions stabilize, the valves are adjusted to continuously supply the gallium source and oxygen into the growth chamber. The aluminum source is controlled using a pulsed on / off cycle, specifically set to open for 10 seconds, then close, and reopen after a 20-second interval. See [link to relevant documentation] Figure 4This diagram illustrates the timing sequence of the oxygen, gallium, and aluminum sources in this embodiment, specifically the timing sequence of the second pulse growth cycle of the present invention: the oxygen and gallium sources are continuously on, while the aluminum source is controlled according to the aforementioned pulse mode. The above periodic growth process is repeated, and the growth rate is measured in real-time using in-situ reflectivity monitoring. Based on this, the total growth time is adjusted to control the epitaxial film thickness at 1000 nm, thus completing the pulsed Al atom-assisted growth of gallium oxide thin films.

[0109] This embodiment enables the fabrication of gallium oxide thin films with high crystallinity and low surface roughness, which can be used in the fabrication of high-voltage diode devices. See also Figure 5 , Figure 5 This is a surface morphology image of a gallium oxide thin film prepared using the method of this invention. See also... Figure 6 , Figure 6 These are surface morphology images of gallium oxide films prepared without the method of this invention. The comparison shows that the gallium oxide film prepared using the method of this invention has a flatter surface, with no obvious protrusions or depressions, a significantly reduced number of island particles that are sparsely distributed, and a lower overall root-mean-square (RMS) roughness. See also... Figure 7 , Figure 7 This is a comparison of the XRD rocking curves of gallium oxide films prepared using the method of this invention and those prepared without this invention. As shown in the figure, the gallium oxide film prepared using the method of this invention has a smaller full width at half maximum (FWHM) of its XRD rocking curve. This indicates that the gallium oxide film prepared by this invention has a lower defect density and superior crystal quality. These results collectively confirm that this invention, while improving the surface smoothness and reducing roughness of gallium oxide films, can significantly reduce defect density and improve crystal quality, fully demonstrating the technical advantages of this invention in optimizing gallium oxide film preparation.

[0110] In summary, this invention provides an epitaxial growth method for gallium oxide thin films, solving the technical problems of poor film quality caused by random island nucleation and anisotropic etching in gallium oxide epitaxial growth, as well as the complexity of the process and the narrow applicability. The method includes: ultrasonic cleaning of the substrate; annealing; pre-deposition of mixed Al and In atoms; and pulsed Al atom-assisted growth of the gallium oxide thin film. This invention is based on a mixed atomic layer of Al and In atoms, leveraging the wetting effect of In atoms to enhance the surface diffusion ability of Al atoms. A novel auxiliary method is constructed in the gallium oxide epitaxial growth process, innovatively using Al atoms as the pulsed auxiliary source. Two cyclic patterns for gallium oxide growth assisted by pulsed Al atoms are designed to provide sufficient diffusion time for Al atoms to avoid local enrichment, further promoting their diffusion migration and uniform distribution on the surface. This targeted innovative design in basic structure construction and growth process control enables Al atoms to achieve an appropriate and uniform distribution on the substrate surface. The present invention utilizes a suitable and uniformly distributed amount of Al atoms, which not only enhances the surface stability of gallium oxide, inhibits its decomposition and anisotropic etching to reduce defects, but also serves as a preferential nucleation site for Ga and O atoms, effectively reducing non-ideal random island nucleation and ultimately achieving a significant improvement in the quality of gallium oxide thin films. This invention is used to prepare gallium oxide thin films with low surface roughness and high crystallinity, and can be applied to the fabrication of high-voltage, high-current power electronic devices and high-sensitivity solar-blind ultraviolet photodetectors.

Claims

1. A method for epitaxial growth of gallium oxide thin film material, characterized in that, The steps include the following: Step 1: Ultrasonic cleaning of the substrate: For substrates used for epitaxial growth of gallium oxide thin films, ultrasonic cleaning is performed using acid and organic solutions; Step 2 Annealing: The ultrasonically cleaned substrate is annealed in an annealing furnace to obtain an annealed substrate; Step 3: Pre-deposition of Al and In atoms: Select gallium oxide epitaxial growth equipment based on substrate size and growth rate requirements, including molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) equipment; precisely control the equivalent flow ratio of Al source and In source through epitaxial growth equipment, mix and pre-deposit Al atoms and In atoms on the annealed substrate surface to form a mixed atomic layer of Al and In atoms with a thickness of 1-3 nm; Step 4: Pulsed Al-Atom-Assisted Growth of Gallium Oxide Thin Films: Using the selected gallium oxide epitaxial growth equipment, an Al-atom-assisted growth method is adopted; two gallium oxide growth cycles with pulsed Al atoms as assistance are set, and the pulse duty cycle is precisely controlled to be 1:3; the equivalent flow rate of the aluminum source is controlled so that the Al composition in the gallium oxide thin film is less than 1%; gallium oxide thin films are periodically grown on the mixed atomic layer of deposited Al atoms and In atoms to complete the epitaxial growth of gallium oxide thin film materials with a thickness of 100-1000 nm, and a substrate with gallium oxide thin film grown is obtained.

2. The epitaxial growth method for gallium oxide thin film material according to claim 1, characterized in that, The substrate described in step 1 may be made of gallium oxide, sapphire, or magnesium oxide as the substrate material.

3. The epitaxial growth method for gallium oxide thin film material according to claim 1, characterized in that, The ultrasonic cleaning of the substrate described in step 1 specifically refers to substrates used for epitaxial growth of gallium oxide thin films. Ultrasonic cleaning is performed using acid and organic solutions, and includes the following steps: 1.1 Acid solution ultrasonic cleaning: Immerse the substrate in HF solution and place it in a water bath. First, perform low-frequency ultrasonic treatment for 3-5 minutes, then switch to high-frequency ultrasonic treatment for 3-5 minutes, and then rinse with deionized water for 3-5 minutes to obtain an acid solution ultrasonically cleaned substrate. 1.2 Ultrasonic cleaning with organic solutions: 1.2.1 Place the substrate that has been ultrasonically cleaned with acid solution in acetone solution and place the whole substrate in a water bath. First, treat it with low frequency ultrasound for 3 to 5 minutes, and then switch to high frequency ultrasound for 3 to 5 minutes to obtain a substrate that has been ultrasonically cleaned with acetone solution. 1.2.2 Place the substrate that has been ultrasonically cleaned with acetone solution into isopropanol solution and place the whole substrate in a water bath. Sort it with low-frequency ultrasound for 3 to 5 minutes, then rinse it with deionized water for 3 to 5 minutes, and finally dry it with a nitrogen gun to complete the ultrasonic cleaning of the substrate.

4. The epitaxial growth method for gallium oxide thin film material according to claim 1, characterized in that, Step 3, the mixed pre-deposition of Al atoms and In atoms, is achieved through the following steps: 3.1 Select epitaxial equipment based on substrate size and growth rate requirements: For epitaxial growth with small substrate size and atomically precise control of film thickness, MBE equipment is selected for epitaxial growth; for epitaxial growth with large substrate size and high growth rate, MOCVD equipment is selected for epitaxial growth. 3.2 Setting the epitaxial process conditions: Place the annealed substrate into the selected epitaxial growth equipment and use a mechanical pump to fill the equipment pipes and growth chamber; set the epitaxial process conditions for mixed pre-deposition of Al atoms and In atoms according to the selected equipment type, wherein the equivalent flow ratio of Al source to In source is controlled at 1:1 to 1:

3. 3.3 Growth of a mixed atomic layer of Al and In atoms: Under the set epitaxial process conditions, Al and In atoms are simultaneously deposited on the surface of the annealed substrate in the selected equipment chamber to form a mixed pre-deposited atomic layer of Al and In atoms with a thickness of 1-3 nm and uniform distribution.

5. The epitaxial growth method for gallium oxide thin film material according to claim 4, characterized in that, Step 3.2, setting the process conditions for the epitaxial equipment, includes: 3.2.1 When using MBE equipment: Set the growth temperature to 600–800℃ and the chamber pressure to 1×10⁻⁶. -5 ~2×10 -5 Torr, the equivalent pressure of the aluminum beam is 2 × 10⁻⁶ -9 ~6×10 -9 Torr, the equivalent pressure of the indium beam is 2 × 10⁻⁶ -9 ~6×10 -9 Torr, the equivalent pressure ratio of aluminum beam to indium beam is 1:1 to 1:3; 3.2.2 When using MOCVD equipment: set the reaction chamber temperature to 700-900℃, the pressure to 40-100mbar, use argon as the carrier gas, trimethylaluminum as the aluminum source, and trimethylindium as the indium source. Set the flow rate of trimethylaluminum to 2-6 sccm, the flow rate of trimethylindium to 2-6 sccm, and the flow rate ratio of trimethylaluminum to trimethylindium to 1:1-1:

3.

6. The epitaxial growth method for gallium oxide thin film material according to claim 4, characterized in that, Step 3.3 describes the growth of a mixed atomic layer of Al and In atoms, which includes: 3.3.1 Deposition process using MBE equipment: The beam baffles for aluminum and indium beams are turned on, so that the two beams act together on the substrate surface in the chamber. The wetting effect of In atoms can promote the diffusion, migration and uniform distribution of Al atoms on the surface. The growth rate is measured in real time by in-situ monitoring, and the beam baffle opening time is adjusted accordingly to deposit a mixed atomic layer of Al and In atoms with a thickness of 1-3 nm on the annealed substrate surface in the chamber. 3.3.2 Deposition process when using MOCVD equipment: Open the control valves of aluminum source and indium source to allow aluminum source and indium source to enter the reaction chamber together with carrier gas, so that In atoms and Al atoms are deposited together on the substrate surface. In atoms play a role in promoting the migration and diffusion of Al atoms. The growth rate is monitored in real time by monitoring the change of sample reflectivity, and the valve opening time is adjusted accordingly to deposit a mixed atomic layer of Al atoms and In atoms with a thickness of 1-3 nm on the annealed substrate surface.

7. The epitaxial growth method for gallium oxide thin film material according to claim 1, characterized in that, Step 4, pulsed Al atom-assisted growth of gallium oxide thin films, includes the following steps: 4.1 Constructing an assisted growth method: Based on epitaxial equipment, Al atoms are used as pulsed auxiliary sources to participate in the epitaxial growth of gallium oxide. The composition of Al atoms in the gallium oxide film is less than 1%. 4.2 Two gallium oxide growth cycles assisted by pulsed Al atoms were set up: The common feature of the two pulsed growth cycles is that the oxygen source and gallium source are kept continuously on, and the aluminum source is controlled by pulse with a pulse duty cycle of 1:3; The first pulsed growth cycle is that the aluminum source is turned on for 5 seconds and then turned off, and then turned on again after an interval of 10 seconds, which is suitable for the preparation of gallium oxide thin films with a thickness of less than 500 nm; The second pulsed growth cycle is that the aluminum source is turned on for 10 seconds and then turned off, and then turned on again after an interval of 20 seconds, which is suitable for the preparation of gallium oxide thin films with a thickness of more than 500 nm. 4.3 Setting gallium oxide thin film deposition process conditions: Using the epitaxial equipment with the above-mentioned Al and In atom mixed pre-deposition process, maintain a high vacuum environment in the chamber, and set the gallium oxide thin film deposition process parameters according to the type of epitaxial equipment. The equivalent flow rate of the aluminum source should ensure that the Al content in the gallium oxide thin film is less than 1%. 4.4 Growth of gallium oxide thin films: Select the first or second pulse growth cycle, and under the set gallium oxide thin film deposition process conditions, grow gallium oxide thin films with a thickness of 100-1000 nm.

8. The epitaxial growth method for gallium oxide thin film material according to claim 7, characterized in that, Step 4.3, setting the gallium oxide thin film deposition process conditions, includes: 4.3.1 When using MBE equipment: Maintain a high vacuum environment in the chamber, set the substrate temperature to 600–800°C, and the chamber pressure to 1 × 10⁻⁶. -5 ~2×10 -5 Torr, oxygen plasma power is 250-300W, aluminum beam equivalent pressure is 2×10 -9 ~6×10 - 9 Torr, the gallium beam equivalent pressure is 1×10⁻⁶ -7 ~2×10 -7 Torr is used to ensure that the Al component in the grown gallium oxide film is less than 1%; 4.3.2 When using MOCVD equipment: Maintain a high vacuum environment in the chamber, set the reaction chamber temperature to 700-900℃, the pressure to 40-100mbar, use argon as the carrier gas, trimethylaluminum as the aluminum source, trimethylgallium as the gallium source, and oxygen as the oxygen source. The flow rate of trimethylaluminum is 2-6 sccm, and the molar flow rate ratio of trimethylgallium to oxygen is 1:5000-1:200, so that the Al component in the grown gallium oxide film is less than 1%.

9. The epitaxial growth method for gallium oxide thin film material according to claim 7, characterized in that, The gallium oxide thin film growth described in step 4.4 includes: 4.4.1 Gallium oxide thin film growth process using MBE equipment: The gallium beam baffle and oxygen plasma are turned on to continuously act on the sample surface; the aluminum beam is controlled in pulse mode with a pulse duty cycle of 1:

3. One of the pulse growth cycles is used for periodic growth. The growth rate is measured in real time through in-situ monitoring, and the total growth time is adjusted accordingly to control the epitaxial film thickness between 100 and 1000 nm, thus completing the pulsed Al atom-assisted growth of gallium oxide thin film. 4.4.2 Gallium oxide thin film growth process using MOCVD equipment: Gallium source and oxygen are continuously introduced into the growth chamber, and aluminum source is controlled by pulse on / off control with a pulse duty cycle of 1:

3. One of the pulse growth cycles is used for periodic growth. The growth rate is monitored in real time by monitoring the change in sample reflectivity, and the valve opening time is adjusted accordingly to control the epitaxial film thickness between 100 and 1000 nm, thus completing the pulsed Al atom-assisted growth of gallium oxide thin film.

10. The epitaxial growth method of gallium oxide thin film material according to claim 1, characterized in that, The gallium oxide thin films prepared according to claims 1-9 are suitable for the following application scenarios: 10.1 Applicable to power electronic device fabrication: When the substrate is gallium oxide material, the gallium oxide thin film prepared by epitaxial growth according to the present invention is suitable for fabricating high voltage and high current power electronic devices, specifically for fabricating diodes and transistors with low on-resistance and low power loss; 10.2 Applicable to optoelectronic device fabrication: When the substrate is sapphire or magnesium oxide, the gallium oxide thin film prepared by epitaxial growth according to the present invention can be used to fabricate solar-blind ultraviolet photodetector devices, which have high sensitivity response to light signals in the deep ultraviolet band.

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