Gallium oxide thin films, their preparation methods and applications

Abstract

This application provides a gallium oxide thin film, its preparation method, and its application. The method for preparing the gallium oxide thin film includes: providing a gallium oxide ceramic target, which comprises any one of silicon-tin co-doped, zirconium-tin co-doped, and hafnium-tin co-doped materials, wherein the doping concentration of Sn atoms is 0.5~1 mol%, and the doping concentrations of Si, Zr, and Hf atoms are all greater than 0 and less than or equal to 1 mol%; placing a substrate in a deposition chamber, adjusting the distance between the substrate and the gallium oxide ceramic target, and adjusting the vacuum level of the deposition chamber to 10... ‑5 The process involves: substrate heating to 550-650°C; maintaining a constant deposition chamber temperature; and using pulsed laser deposition to grow a gallium oxide thin film on the substrate surface; oxygen pressure less than or equal to 40 mTorr; in-situ annealing within the deposition chamber to obtain the gallium oxide thin film; and maintaining the same oxygen pressure as during deposition during annealing. This application achieves high-quality gallium oxide thin film growth and effective modulation of resistivity by controlling the substrate heating temperature, oxygen pressure, and the doping concentrations of Sn, Si, Zr, and Hf atoms.

Description

Technical Field

[0001] This application relates to the field of semiconductor materials technology, and in particular to a gallium oxide thin film, its preparation method, and its application. Background Technology

[0002] Gallium oxide (Ga₂O₃), as a new generation of ultrawide bandgap semiconductor material, has five phase structures (α, β, γ, δ, and ε phases). Among them, the β phase has the most stable crystal structure and can grow bulk β-Ga₂O₃ single crystals from melt, thus achieving homoepitaxial growth. Therefore, most current research focuses on β-Ga₂O₃. Metastable ε-Ga₂O₃ belongs to the hexagonal crystal system with a bandgap of 4.9 eV and an optical absorption edge close to 250 nm. Theoretically, it has a higher breakdown voltage (approximately 8 MV / cm) and a Balix figure of merit (approximately 3444) than β-Ga₂O₃. Furthermore, the strong spontaneous polarization generated in the lattice structure of ε-Ga₂O₃ allows for the construction of heterojunctions to obtain a high concentration of two-dimensional electron gas at the interface, which helps to improve electron mobility. Furthermore, compared to the monoclinic β-Ga₂O₃, the ε phase exhibits a better lattice match with other hexagonal substrate materials (such as Al₂O₃, GaN, and 6H-SiC), which facilitates the acquisition of high-quality epitaxial films using inexpensive heterostructure substrates and makes commercialization easier. Therefore, ε-Ga₂O₃ holds great potential for future applications in high-power power electronic devices and solar-blind ultraviolet photodetectors.

[0003] Currently, the epitaxial growth of pure-phase ε-Ga₂O₃ thin films has been achieved using common methods such as molecular beam epitaxy (MBE), mist chemical vapor deposition (Mist-CVD), and metal-organic chemical vapor deposition (MOCVD). However, MBE suffers from high equipment costs; ε-Ga₂O₃ films prepared by Mist-CVD and MOCVD exhibit high surface roughness, making efficient activation difficult and hindering the design and fabrication of ε-Ga₂O₃ films with varying resistivities, thus significantly limiting their application in device manufacturing. Summary of the Invention

[0004] This application provides a gallium oxide thin film, its preparation method, and its application, in order to at least solve one of the technical problems existing in the prior art.

[0005] In a first aspect, this application provides a method for preparing a gallium oxide thin film, the method comprising: A gallium oxide ceramic target is provided, wherein the gallium oxide ceramic target includes any one of silicon-tin co-doped, zirconium-tin co-doped, and hafnium-tin co-doped materials, wherein the doping concentration of Sn atoms in the gallium oxide ceramic target is 0.5~1 mol%, and the doping concentrations of Si, Zr, and Hf atoms are all greater than 0 and less than or equal to 1 mol%. After cleaning, the substrate is placed in the deposition chamber. The distance between the substrate and the gallium oxide ceramic target is adjusted, and the vacuum level of the deposition chamber is adjusted to 10. -5 Below Pa; The substrate is heated to 550~650℃ and held at that temperature. Maintaining a constant temperature in the deposition chamber, a gallium oxide thin film is grown on the substrate surface using pulsed laser deposition technology; deposition parameters: oxygen pressure less than or equal to 40 mTorr; After the gallium oxide thin film is grown, it is annealed in situ in the deposition chamber to obtain the gallium oxide thin film; wherein, the same oxygen pressure as during deposition is maintained during annealing.

[0006] In this application, the growth of high-quality gallium oxide thin films and effective regulation of resistivity can be achieved by controlling the substrate heating temperature, oxygen pressure, and silicon-tin doping concentration, zirconium-tin doping concentration, or hafnium-tin doping concentration. Specifically, the resistivity of gallium oxide thin films prepared using this method can be controlled by four orders of magnitude, thus broadening the methods for preparing metastable gallium oxide phases.

[0007] The method of this invention uses pulsed laser deposition technology, which is simple in process. After the gallium oxide thin film is grown, it is annealed in situ in the deposition chamber, which can avoid film contamination and crystal phase transformation caused by post-annealing and make the gallium oxide thin film have high crystallinity.

[0008] In one embodiment, the doping concentration of Si atoms in the gallium oxide ceramic target is 0.5~0.75 mol%, the doping concentration of Zr atoms is 0.5~0.75 mol%, and the doping concentration of Hf atoms is 0.5~0.75 mol%.

[0009] In one embodiment, the substrate heating temperature is 600±30℃; or, The oxygen pressure is 1~30 mTorr. In this application, when the substrate heating temperature is 600±30℃ and the oxygen pressure is in the range of 1~30 mTorr, a gallium oxide thin film with the lowest resistivity can be obtained.

[0010] In one embodiment, the deposition parameters further include: a laser energy density of 1~2.5 J / cm². 2 The pulsed laser frequency is 1~10Hz; or, The distance between the substrate and the gallium oxide ceramic target is 30~100mm.

[0011] In one embodiment, the substrate is heated to 550-650°C at a heating rate of 5-30°C / min and held at that temperature for at least 20 minutes. When the gallium oxide thin film is annealed in situ in the deposition chamber, the cooling rate is 5~30℃ / min.

[0012] In one embodiment, the method further includes: before growing a gallium oxide thin film on the substrate surface using pulsed laser deposition technology, growing a buffer layer on the substrate surface under the same deposition conditions, and growing the gallium oxide thin film on the buffer layer facing away from the substrate surface; The buffer layer uses a gallium oxide ceramic target doped with 0.5 mol% Sn.

[0013] In this application, a buffer layer is introduced between the substrate and the gallium oxide film, which is beneficial for the epitaxial growth of high-quality gallium oxide films.

[0014] In one possible implementation, the method further includes: Pre-deposition was performed before growing the buffer layer and the gallium oxide film. The pre-deposition consisted of 100 pulses, with a 60-second interval, and was repeated 3 times. The pulse laser frequency was 2 Hz.

[0015] Secondly, this application provides a gallium oxide thin film, which is prepared by the preparation method in any of the embodiments of the first aspect.

[0016] In one embodiment, the gallium oxide thin film is a single-phase ε-Ga₂O₃ thin film. The gallium oxide thin film prepared by the method of this application is an ε-Ga₂O₃ thin film. Since the gallium oxide ceramic target used includes any one of silicon-tin co-doped, zirconium-tin co-doped, and hafnium-tin co-doped, the gallium oxide thin film prepared by the method of this application is a silicon-tin co-doped ε-Ga₂O₃ thin film, a zirconium-tin co-doped ε-Ga₂O₃ thin film, or a hafnium-tin co-doped ε-Ga₂O₃ thin film. Moreover, the resistivity of these ε-Ga₂O₃ thin films can be adjusted by controlling the doping concentrations of Sn, Si, Zr, and Hf, as well as the substrate heating temperature and oxygen pressure.

[0017] Thirdly, this application also provides applications of gallium oxide thin films used in electronic devices.

[0018] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0019] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0020] Figure 1 The X-ray diffraction pattern of the ε-Ga2O3 thin film prepared in Example 1 of this application is shown; Figure 2 The X-ray diffraction pattern of the ε-Ga2O3 thin film prepared in Example 2 of this application is shown; Figure 3 The X-ray diffraction pattern of the ε-Ga2O3 thin film prepared in Example 3 of this application is shown; Figure 4 The X-ray diffraction pattern of the ε-Ga2O3 thin film prepared in Example 4 of this application is shown; Figure 5 The X-ray diffraction pattern of the ε-Ga2O3 thin film prepared in Example 5 of this application is shown; Figure 6 The X-ray diffraction pattern of the ε-Ga2O3 thin film prepared in Example 6 of this application is shown; Figure 7 The X-ray diffraction pattern of the ε-Ga2O3 thin film prepared in Example 7 of this application is shown. Detailed Implementation

[0021] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] In a first aspect, this application provides a method for preparing a gallium oxide thin film, the method comprising: Step 1) Provide a gallium oxide ceramic target, which includes any one of silicon-tin co-doped, zirconium-tin co-doped, and hafnium-tin co-doped materials, wherein the doping concentration of Sn atoms in the gallium oxide ceramic target is 0.5~1 mol%, and the doping concentrations of Si, Zr, and Hf atoms are all greater than 0 and less than or equal to 1 mol%. Step 2): After cleaning the substrate, place it in the deposition chamber, adjust the distance between the substrate and the gallium oxide ceramic target from Step 1), and adjust the vacuum level of the deposition chamber to 10. -5 Below Pa; Step 3), heat the substrate to 550~650℃ and hold at that temperature; Step 4), maintain a constant temperature in the deposition chamber, and grow a gallium oxide thin film on the substrate surface using pulsed laser deposition technology; deposition parameters: oxygen pressure less than or equal to 40 mTorr; Step 5) After the gallium oxide film growth is completed, it is annealed in situ in the deposition chamber to obtain the gallium oxide film; wherein, the same oxygen pressure as during deposition is maintained during annealing.

[0023] The gallium oxide thin films prepared by the above method are silicon-tin co-doped ε-Ga₂O₃ thin films, zirconium-tin co-doped ε-Ga₂O₃ thin films, or hafnium-tin co-doped ε-Ga₂O₃ thin films, and the resistivity of these three types of ε-Ga₂O₃ thin films can be tunable. Specifically, in the method of this application, the growth temperature (i.e., substrate heating temperature), oxygen pressure, and silicon-tin doping concentration, zirconium-tin doping concentration, or hafnium-tin doping concentration can be controlled to achieve effective adjustment of the growth and resistivity of high-quality ε-Ga₂O₃ thin films. In addition, the resistivity of the ε-Ga₂O₃ thin films prepared by the method of this application can be controlled by four orders of magnitude, while broadening the preparation method of metastable gallium oxide phases.

[0024] The method described in this application can obtain ε-Ga2O3 thin films with high crystallinity, low surface roughness, and tunable electrical transport properties, laying the foundation for device fabrication.

[0025] The method described in this application employs pulsed laser deposition technology, which is simple in process. After the thin film growth is completed, in-situ annealing is performed in the deposition chamber, which can avoid film contamination and crystal phase transformation caused by post-annealing, resulting in high crystallinity of gallium oxide thin films.

[0026] For example, in step 1), the gallium oxide ceramic target includes any one of silicon-tin co-doped, zirconium-tin co-doped, and hafnium-tin co-doped targets. That is, the corresponding targets are silicon-tin co-doped gallium oxide ceramic targets, zirconium-tin co-doped gallium oxide ceramic targets, and hafnium-tin co-doped gallium oxide ceramic targets, respectively.

[0027] For example, in step 1), taking a silicon-tin co-doped gallium oxide ceramic target as an example (i.e., the gallium oxide ceramic target includes silicon-tin co-doping), the preparation of the silicon-tin co-doped gallium oxide ceramic target is as follows: SiO2, SnO2, and Ga2O3 powders are mixed uniformly, shaped, and sintered to obtain the silicon-tin co-doped gallium oxide ceramic target. For example, the shaping is carried out by cold pressing, the sintering temperature is 1350℃, and the sintering time is 12h. The purity of SiO2 powder, SnO2 powder, and Ga2O3 powder is all greater than 99%. Similarly, zirconium-tin co-doped gallium oxide ceramic targets and hafnium-tin co-doped gallium oxide ceramic targets can also be prepared by the same method.

[0028] For example, in this application, the doping concentration (mol%) = the molar amount of doped atoms / the total molar amount of all oxide raw materials.

[0029] For example, in step 1), the doping concentration of Si atoms is 0.5~0.75 mol%, the doping concentration of Zr atoms is 0.5~0.75 mol%, and the doping concentration of Hf atoms is 0.5~0.75 mol%. In step 1), keeping the Sn doping concentration constant (a fixed value between 0.5 mol% and 1 mol%), the required Si, Zr, or Hf doping concentrations for ε-Ga2O3 films with different electrotransport properties are different. The Si, Zr, or Hf doping concentrations that yield the highest carrier concentration are preferably 0.5 mol%-0.75 mol%.

[0030] For example, the doping concentration of Sn atoms is 0.5 mol%, 0.6 mol%, 0.7 mol%, 0.8 mol%, 0.9 mol%, 1 mol%, and any value between two adjacent values. The doping concentration of Si atoms is 0.5 mol%, 0.6 mol%, 0.7 mol%, 0.75 mol%, and any value between two adjacent values. The doping concentration of Zr atoms is 0.5 mol%, 0.6 mol%, 0.7 mol%, 0.75 mol%, and any value between two adjacent values. The doping concentration of Hf atoms is 0.5 mol%, 0.6 mol%, 0.7 mol%, 0.75 mol%, and any value between two adjacent values.

[0031] For example, in step 2), the substrate can be C-plane sapphire, SiC or GaN as the growth substrate.

[0032] The substrate cleaning method is as follows: the substrate is ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water, and then dried with high-purity nitrogen.

[0033] For example, in step 2), the distance between the substrate and the gallium oxide ceramic target in step 1) is 30~100mm. Preferably, the distance between the substrate and the gallium oxide ceramic target in step 1) is 50mm.

[0034] For example, in step 3), the substrate heating temperature is 550°C, 570°C, 600°C, 630°C, 650°C, or any value between two adjacent values. In step 3), the substrate is heated to 550-650°C at a heating rate of 5-30°C / min and held at that temperature for at least 20 minutes.

[0035] Preferably, to obtain the lowest gallium oxide thin film resistivity, the required substrate heating temperature is 600±30℃, the heating rate is 20℃ / min, and the holding time is 30min.

[0036] For example, in step 4), a gallium oxide thin film is deposited using pulsed laser deposition technology under conditions ranging from the vacuum level in the deposition chamber of step 2) to an oxygen pressure of 40 mTorr. Preferably, the oxygen pressure is 1 to 30 mTorr. Exemplarily, this oxygen pressure is any value between 1 mTorr, 5 mTorr, 10 mTorr, 20 mTorr, 25 mTorr, 30 mTorr, and adjacent values. More preferably, the oxygen pressure is 1 to 20 mTorr. More preferably, in step 4), the oxygen pressure required to obtain the lowest resistivity of the gallium oxide thin film is 10 mTorr.

[0037] For example, in step 4), when using pulsed laser deposition technology, the deposition parameters also include: laser energy density of 1~2.5 J / cm². 2 The pulsed laser frequency is 1~10Hz. Preferably, the laser energy density is 2J / cm². 2 The pulsed laser frequency is 5Hz.

[0038] For example, in step 4), before the gallium oxide thin film is grown, a pre-deposition is performed. The pre-deposition is performed by 100 pulses, with a 60-second interval and 3 cycles. The pulse laser frequency is 2Hz.

[0039] For example, in step 5), when the gallium oxide film is annealed in situ in the deposition chamber, the cooling rate is 5~30℃ / min. The gallium oxide film is removed after the temperature in the deposition chamber drops below 100℃. Preferably, the cooling rate is 20℃ / min.

[0040] For example, the method of this application further includes: before growing a gallium oxide thin film on the substrate surface using pulsed laser deposition technology, growing a buffer layer on the substrate surface under the same deposition conditions, and then growing a gallium oxide thin film on the buffer layer facing away from the substrate surface. The buffer layer uses a 0.5 mol% Sn-doped gallium oxide ceramic target. Exemplarily, this 0.5 mol% Sn-doped gallium oxide ceramic target is prepared by uniformly mixing SnO2 and Ga2O3 powders, molding, and sintering to obtain the Sn-doped gallium oxide ceramic target. The Sn doping concentration in this target is 0.5 mol%. Exemplarily, cold pressing is used for molding, the sintering temperature is 1350℃, and the sintering time is 12 hours. The purity of both the SnO2 and Ga2O3 powders is greater than 99%.

[0041] In this application, before growing the thin film, an ε-Ga₂O₃ layer with a Sn doping concentration of 0.5 mol% is first grown as a buffer layer under the same conditions. The introduction of the buffer layer between the substrate and the gallium oxide thin film is beneficial to the epitaxial growth of high-quality ε-Ga₂O₃ thin films.

[0042] Furthermore, the method of this application also includes: pre-deposition before growing the buffer layer, the pre-deposition being performed by 100 pulses, with an interval of 60 seconds and repeated 3 times, and the pulse laser frequency being 2Hz.

[0043] Secondly, this application discloses a gallium oxide thin film, which is prepared by the above-described preparation method. The gallium oxide thin film is a single-phase ε-Ga₂O₃ thin film, specifically, the gallium oxide thin film prepared by the method of this application is a silicon-tin co-doped ε-Ga₂O₃ thin film, a zirconium-tin co-doped ε-Ga₂O₃ thin film, or a hafnium-tin co-doped ε-Ga₂O₃ thin film. The electrical transport properties of the ε-Ga₂O₃ thin film can be stably controlled by Si and Sn co-doping, Zr and Sn co-doping, or Hf and Sn co-doping. The gallium oxide thin film of this application can be used in electronic devices. These electronic devices include, but are not limited to, high-power power electronic devices and solar-blind ultraviolet photodetectors.

[0044] The present application will be further described in detail below with reference to the embodiments.

[0045] Example 1 Example 1 describes the preparation of a gallium oxide thin film, specifically an ε-Ga₂O₃ thin film co-doped with 1 mol% Si and 0.5 mol% Sn, comprising the following steps: Step (1) provides a gallium oxide ceramic target, which includes silicon and tin co-doping. Specifically, SiO2, SnO2 and Ga2O3 powders with a purity greater than 99.99% are mixed uniformly in a molar ratio of 1:0.5:98.5. The total mass of the mixed powder is 8g. The powder is pressed by cold pressing at a pressure of 10MPa for 1min. Then it is placed in a tube furnace and sintered at 1350℃ for 12h to obtain a gallium oxide ceramic target co-doped with 1mol% Si and 0.5mol% Sn. The target material used for the buffer layer is a 0.5 mol% Sn-doped gallium oxide ceramic target. Specifically, SnO2 and Ga2O3 powders with a purity greater than 99.99% are mixed uniformly at a molar ratio of 0.5:99.5, and the total mass of the mixed powder is 8g. The mixture is pressed by cold pressing at a pressure of 10MPa for 1min, and then placed in a tube furnace for sintering at 1350℃ for 12h to obtain the 0.5 mol% Sn-doped gallium oxide ceramic target. The obtained target material is fixed on the target material holder in the deposition chamber; Step (2): Select a 5mm×5mm c-plane sapphire as the growth substrate, and clean it with acetone, anhydrous ethanol and deionized water in sequence by ultrasonic cleaning. Then dry it with high-purity nitrogen to obtain a cleaned substrate. Step (3): Fix the cleaned substrate to the center of the substrate tray with silver paste, then place it in the deposition chamber. Adjust the distance between the substrate and the two targets from step (1) to 50 mm, and adjust the vacuum level of the deposition chamber to 10. -5 Below Pa; Step (4): Heat the substrate to 550°C at a heating rate of 20°C / min and hold for 30 min. Step (5), growing a buffer layer on the substrate surface and growing a gallium oxide thin film on the buffer layer facing away from the substrate surface, specifically involves: using a pulsed laser deposition system, introducing high-purity oxygen, and controlling the oxygen pressure to 20 mTorr; setting the laser energy density to 2 J / cm². 2 The pulsed laser frequency is 5Hz, the buffer layer is pulsed 5000 times, followed by the gallium oxide film pulsed 5000 times; the buffer layer and the gallium oxide film are pre-deposited 100 times at a frequency of 2Hz before growth, with an interval of 60s and 3 cycles; the thickness of the buffer layer is 100nm. Step (6): After the gallium oxide thin film growth is completed, it is annealed in situ in the deposition chamber at a cooling rate of 20°C / min. During the annealing, the same oxygen pressure as during deposition is maintained. Step (7): After the temperature drops below 100°C, remove the gallium oxide thin film sample.

[0046] Figure 1 This is an X-ray diffraction pattern of the ε-Ga2O3 thin film prepared by the method in Example 1.

[0047] The root mean square roughness (RMS) of the ε-Ga2O3 thin film prepared in Example 1 was measured by atomic force microscopy (AFM), and the RMS value was 0.37 nm.

[0048] Root mean square roughness (RMS) is a quantitative index calculated from thin film surface morphology data obtained by atomic force microscopy (AFM). A smaller RMS value indicates a smoother thin film surface.

[0049] Example 2 Example 2 describes the preparation of a gallium oxide thin film, specifically an ε-Ga₂O₃ thin film co-doped with 1 mol% Si and 0.5 mol% Sn, comprising the following steps: Step (1) provides a gallium oxide ceramic target, which includes silicon and tin co-doping. Specifically, SiO2, SnO2 and Ga2O3 powders with a purity greater than 99.99% are mixed uniformly in a molar ratio of 1:0.5:98.5 to obtain a mixed powder. The total mass of the mixed powder is 8g. It is pressed by cold pressing at a pressure of 10MPa and held for 1min. Then it is placed in a tube furnace and sintered at 1350℃ for 12h to obtain a gallium oxide ceramic target co-doped with 1mol% Si and 0.5mol% Sn. The target material used for the buffer layer is a gallium oxide ceramic target doped with 0.5 mol% Sn, and the method is the same as in Example 1; The obtained target material is fixed on the target material holder in the deposition chamber; Step (2): Select a 5mm×5mm c-plane sapphire as the growth substrate, and clean it with acetone, anhydrous ethanol and deionized water in sequence by ultrasonic cleaning. Then dry it with high-purity nitrogen to obtain a cleaned substrate. Step (3): Fix the cleaned substrate to the center of the substrate tray with silver paste, then place it in the deposition chamber. Adjust the distance between the substrate and the two targets from step (1) to 50 mm, and adjust the vacuum level of the deposition chamber to 10. -5 Below Pa; Step (4): Heat the substrate to 600°C at a heating rate of 20°C / min and hold for 30 min. Step (5), growing a buffer layer on the substrate surface and growing a gallium oxide thin film on the buffer layer facing away from the substrate surface, specifically involves: using a pulsed laser deposition system, introducing high-purity oxygen, and controlling the oxygen pressure to 20 mTorr; setting the laser energy density to 2 J / cm². 2 The pulsed laser frequency is 5Hz, the buffer layer is pulsed 5000 times, followed by the gallium oxide film pulsed 5000 times; the buffer layer and the gallium oxide film are pre-deposited 100 times at a frequency of 2Hz before growth, with an interval of 60s and 3 cycles; the thickness of the buffer layer is 100nm. Step (6): After the gallium oxide thin film growth is completed, it is annealed in situ in the deposition chamber at a cooling rate of 20°C / min. During the annealing, the same oxygen pressure as during deposition is maintained. Step (7): After the temperature drops below 100°C, remove the gallium oxide thin film sample.

[0050] Figure 2 This is an X-ray diffraction pattern of the ε-Ga2O3 thin film prepared by the method in Example 2.

[0051] The root mean square roughness (RMS) of the ε-Ga2O3 thin film prepared in Example 2 was measured by atomic force microscopy (AFM), and the RMS value was 0.42 nm.

[0052] Example 3 Example 3 describes the preparation of a gallium oxide thin film, specifically an ε-Ga₂O₃ thin film co-doped with 1 mol% Si and 0.5 mol% Sn, comprising the following steps: Step (1) provides a gallium oxide ceramic target, which includes silicon and tin co-doping. Specifically, SiO2, SnO2 and Ga2O3 powders with a purity greater than 99.99% are mixed uniformly in a molar ratio of 1:0.5:98.5 to obtain a mixed powder. The total mass of the mixed powder is 8g. It is pressed by cold pressing at a pressure of 10MPa and held for 1min. Then it is placed in a tube furnace and sintered at 1350℃ for 12h to obtain a gallium oxide ceramic target co-doped with 1mol% Si and 0.5mol% Sn. The target material used for the buffer layer is a 0.5 mol% Sn-doped gallium oxide ceramic target, and the preparation method is the same as in Example 1; The obtained target material is fixed on the target material holder in the deposition chamber; Step (2): Select a 5mm×5mm c-plane sapphire as the growth substrate, and clean it with acetone, anhydrous ethanol and deionized water in sequence by ultrasonic cleaning. Then dry it with high-purity nitrogen to obtain a cleaned substrate. Step (3): Fix the cleaned substrate to the center of the substrate tray with silver paste, then place it in the deposition chamber. Adjust the distance between the substrate and the two targets from step (1) to 50 mm, and adjust the vacuum level of the deposition chamber to 10. -5 Below Pa; Step (4): Heat the substrate to 650°C at a heating rate of 20°C / min and hold for 30 min. Step (5), growing a buffer layer on the substrate surface and growing a gallium oxide thin film on the buffer layer facing away from the substrate surface, specifically involves: using a pulsed laser deposition system, introducing high-purity oxygen, and controlling the oxygen pressure to 20 mTorr; setting the laser energy density to 2 J / cm². 2 The pulsed laser frequency is 5Hz, the buffer layer is pulsed 5000 times, followed by the gallium oxide film pulsed 5000 times; the buffer layer and the gallium oxide film are pre-deposited 100 times at a frequency of 2Hz before growth, with an interval of 60s and 3 cycles; the thickness of the buffer layer is 100nm. Step (6): After the gallium oxide thin film growth is completed, it is annealed in situ in the deposition chamber at a cooling rate of 20°C / min. During the annealing, the same oxygen pressure as during deposition is maintained. Step (7): After the temperature drops below 100°C, remove the gallium oxide thin film sample.

[0053] Figure 3 This is an X-ray diffraction pattern of the ε-Ga2O3 thin film prepared by the method in Example 3.

[0054] The root mean square roughness (RMS) of the ε-Ga2O3 thin film prepared in Example 3 was measured by atomic force microscopy (AFM), and the RMS value was 0.25 nm.

[0055] Example 4 Example 4 describes the preparation of a gallium oxide thin film, specifically an ε-Ga₂O₃ thin film co-doped with 1 mol% Si and 0.5 mol% Sn, comprising the following steps: Step (1): A gallium oxide ceramic target is provided, which includes silicon and tin co-doping. Specifically, SiO2, SnO2 and Ga2O3 powders with a purity greater than 99.99% are mixed uniformly in a molar ratio of 1:0.5:98.5 to obtain a mixed powder. The total mass of the mixed powder is 8g. The powder is pressed by cold pressing at a pressure of 10MPa for 1min. Then, it is placed in a tube furnace and sintered at 1350℃ for 12h to obtain a gallium oxide ceramic target co-doped with 1mol% Si and 0.5mol% Sn. The obtained target is fixed on the target holder in the deposition chamber. Step (2): Select a 5mm×5mm c-plane sapphire as the growth substrate, and clean it with acetone, anhydrous ethanol and deionized water in sequence by ultrasonic cleaning. Then dry it with high-purity nitrogen to obtain a cleaned substrate. Step (3): Fix the cleaned substrate to the center of the substrate tray with silver paste, then place it in the deposition chamber, adjust the distance between the substrate and the target to 50 mm, and adjust the vacuum level of the deposition chamber to 10. -5 Below Pa; Step (4): Heat the substrate to 600°C at a heating rate of 20°C / min and hold for 30 min. Step (5) involves growing a gallium oxide thin film on the substrate surface, specifically: using a pulsed laser deposition system, introducing high-purity oxygen, and controlling the oxygen pressure to 10 mTorr; setting the laser energy density to 2 J / cm². 2 The pulsed laser frequency is 5Hz, and the thin film pulses 10,000 times; before thin film growth, pre-deposit at a frequency of 2Hz 100 times, with an interval of 60s and 3 cycles. Step (6): After the gallium oxide thin film growth is completed, it is annealed in situ in the deposition chamber at a cooling rate of 20°C / min. During the annealing, the same oxygen pressure as during deposition is maintained. Step (7): After the temperature drops below 100°C, remove the gallium oxide thin film sample.

[0056] Figure 4 This is an X-ray diffraction pattern of the ε-Ga2O3 thin film prepared by the method in Example 4.

[0057] The root mean square roughness (RMS) of the ε-Ga2O3 thin film prepared in Example 4 was measured by atomic force microscopy (AFM), and the RMS value was 0.48 nm.

[0058] Example 5 Example 5 describes the preparation of a gallium oxide thin film, specifically an ε-Ga₂O₃ thin film co-doped with 1 mol% Si and 0.5 mol% Sn, comprising the following steps: Step (1): A gallium oxide ceramic target is provided, which includes silicon and tin co-doping. Specifically, SiO2, SnO2 and Ga2O3 powders with a purity greater than 99.99% are mixed uniformly in a molar ratio of 1:0.5:98.5 to obtain a mixed powder. The total mass of the mixed powder is 8g. The powder is pressed by cold pressing at a pressure of 10MPa for 1min. Then, it is placed in a tube furnace and sintered at 1350℃ for 12h to obtain a gallium oxide ceramic target co-doped with 1mol% Si and 0.5mol% Sn. The obtained target is fixed on the target holder in the deposition chamber. Step (2): Select a 5mm×5mm c-plane sapphire as the growth substrate, and clean it with acetone, anhydrous ethanol and deionized water in sequence by ultrasonic cleaning. Then dry it with high-purity nitrogen to obtain a cleaned substrate. Step (3): Fix the cleaned substrate to the center of the substrate tray with silver paste, then place it in the deposition chamber, adjust the distance between the substrate and the target to 50 mm, and adjust the vacuum level of the deposition chamber to 10. -5 Below Pa; Step (4): Heat the substrate to 600°C at a heating rate of 20°C / min and hold for 30 min. Step (5) involves growing a gallium oxide thin film on the substrate surface, specifically: using a pulsed laser deposition system, introducing high-purity oxygen, and controlling the oxygen pressure to 1 mTorr; setting the laser energy density to 2 J / cm². 2 The frequency was 5Hz, and the thin film pulses were 10,000 times; before the thin film growth, a pre-deposition was performed at a frequency of 2Hz for 100 times, with an interval of 60s and 3 cycles. Step (6): After the gallium oxide thin film growth is completed, it is annealed in situ in the deposition chamber at a cooling rate of 20°C / min. During the annealing, the same oxygen pressure as during deposition is maintained. Step (7): After the temperature drops below 100°C, remove the gallium oxide thin film sample.

[0059] Figure 5 This is an X-ray diffraction pattern of the ε-Ga2O3 thin film prepared by the method in Example 5.

[0060] The root mean square roughness (RMS) of the ε-Ga2O3 thin film prepared in Example 5 was measured by atomic force microscopy (AFM), and the RMS value was 0.21 nm.

[0061] Example 6 Example 6 describes the preparation of a gallium oxide thin film, specifically an ε-Ga₂O₃ thin film co-doped with 0.75 mol% Si and 0.5 mol% Sn, comprising the following steps: Step (1) provides a gallium oxide ceramic target, which includes silicon and tin co-doping. Specifically, SiO2, SnO2 and Ga2O3 powders with a purity greater than 99.99% are mixed uniformly in a molar ratio of 0.75:0.5:98.75 to obtain a mixed powder. The total mass of the mixed powder is 8g. It is pressed by cold pressing at a pressure of 10MPa and held for 1min. Then it is placed in a tube furnace and sintered at 1350℃ for 12h to obtain a gallium oxide ceramic target co-doped with 0.75mol% Si and 0.5mol% Sn. The target material used for the buffer layer is a 0.5 mol% Sn-doped gallium oxide ceramic target, and the preparation method is the same as in Example 1; The obtained target material is fixed on the target material holder in the deposition chamber; Step (2): Select a 5mm×5mm c-plane sapphire as the growth substrate, and clean it with acetone, anhydrous ethanol and deionized water in sequence by ultrasonic cleaning. Then dry it with high-purity nitrogen to obtain a cleaned substrate. Step (3): Fix the cleaned substrate to the center of the substrate tray with silver paste, then place it in the deposition chamber. Adjust the distance between the substrate and the two targets from step (1) to 50 mm, and adjust the vacuum level of the deposition chamber to 10. -5 Below Pa; Step (4): Heat the substrate to 600°C at a heating rate of 20°C / min and hold for 30 min. Step (5), growing a buffer layer on the substrate surface and growing a gallium oxide thin film on the buffer layer facing away from the substrate surface, specifically involves: using a pulsed laser deposition system, introducing high-purity oxygen, and controlling the oxygen pressure to 10 mTorr; setting the laser energy density to 2 J / cm². 2 The pulsed laser frequency is 5Hz, the buffer layer is pulsed 1000 times, and then the gallium oxide film is pulsed 9000 times; the buffer layer and the gallium oxide film are pre-deposited at a frequency of 2Hz 100 times before growth, with an interval of 60s and 3 cycles; the thickness of the buffer layer is 20nm. Step (6): After the gallium oxide thin film growth is completed, it is annealed in situ in the deposition chamber at a cooling rate of 20°C / min. During the annealing, the same oxygen pressure as during deposition is maintained. Step (7): After the temperature drops below 100°C, remove the gallium oxide thin film sample.

[0062] Figure 6 This is an X-ray diffraction pattern of the ε-Ga2O3 thin film prepared by the method in Example 6.

[0063] The root mean square roughness (RMS) of the ε-Ga2O3 thin film prepared in Example 6 was measured by atomic force microscopy (AFM), and the RMS value was 0.52 nm.

[0064] Example 7 This embodiment prepares a gallium oxide thin film, which is an ε-Ga2O3 thin film co-doped with 0.5 mol% Si and 0.5 mol% Sn, specifically including the following steps: Step (1) provides a gallium oxide ceramic target, which includes silicon and tin co-doping. Specifically, SiO2, SnO2 and Ga2O3 powders with a purity greater than 99.99% are mixed uniformly in a molar ratio of 0.5:0.5:99 to obtain a mixed powder. The total mass of the mixed powder is 8g. It is pressed by cold pressing at a pressure of 10MPa and held for 1min. Then it is placed in a tube furnace and sintered at 1350℃ for 12h to obtain a gallium oxide ceramic target co-doped with 0.5mol% Si and 0.5mol% Sn. The target material used for the buffer layer is a 0.5 mol% Sn-doped gallium oxide ceramic target, and the preparation method is the same as in Example 1; The obtained target material is fixed on the target material holder in the deposition chamber; Step (2): Select a 5mm×5mm c-plane sapphire as the growth substrate, and clean it with acetone, anhydrous ethanol and deionized water in sequence by ultrasonic cleaning. Then dry it with high-purity nitrogen to obtain a cleaned substrate. Step (3): Fix the cleaned substrate to the center of the substrate tray with silver paste, then place it in the deposition chamber. Adjust the distance between the substrate and the two targets from step (1) to 50 mm, and adjust the vacuum level of the deposition chamber to 10. -5 Below Pa; Step (4): Heat the substrate to 600°C at a heating rate of 20°C / min and hold for 30 min. Step (5), growing a buffer layer on the substrate surface and growing a gallium oxide thin film on the buffer layer facing away from the substrate surface, specifically involves: using a pulsed laser deposition system, introducing high-purity oxygen, and controlling the oxygen pressure to 10 mTorr; setting the laser energy density to 2 J / cm². 2The pulsed laser frequency is 5Hz, the buffer layer is pulsed 1000 times, and then the gallium oxide film is pulsed 9000 times; the buffer layer and the gallium oxide film are pre-deposited at a frequency of 2Hz 100 times before growth, with an interval of 60s and 3 cycles; the thickness of the buffer layer is 20nm. Step (6): After the gallium oxide thin film growth is completed, it is annealed in situ in the deposition chamber at a cooling rate of 20°C / min. During the annealing, the same oxygen pressure as during deposition is maintained. Step (7): After the temperature drops below 100°C, remove the gallium oxide thin film sample.

[0065] Figure 7 This is an X-ray diffraction pattern of the ε-Ga2O3 thin film prepared by the method in Example 7.

[0066] The root mean square roughness (RMS) of the ε-Ga2O3 thin film prepared in Example 7 was measured by atomic force microscopy (AFM), and the RMS value was 0.37 nm.

[0067] Performance test results (1) The electrical properties of the gallium oxide thin films prepared in Examples 1 to 7 were tested respectively. The resistivity of each gallium oxide thin film was tested by the van der Bauer method, and the test results are shown in Table 1.

[0068] Table 1 Resistivity of gallium oxide thin films

[0069] As shown in Table 1, the gallium oxide thin film prepared by the method of this application is a single-phase ε-Ga2O3 thin film, and the preparation of a conductive ε-Ga2O3 thin film has been achieved.

[0070] (2), Figure 1-7 The X-ray diffraction (XRD) patterns of the gallium oxide thin films prepared in Examples 1-7 are shown below. In addition to the diffraction peaks of α-Al₂O₃ (as the sapphire substrate material), these XRD patterns also show distinct diffraction peaks at 19.15°, 38.80°, 59.75°, and 83.18°, which are attributed to the (002), (004), (006), and (008) crystal planes of the ε-Ga₂O₃ peak, respectively. Furthermore, no diffraction peaks of other Ga₂O₃ phases, such as β-Ga₂O₃, were detected in these XRD patterns, indicating that the method described in this application yields a highly crystalline single-phase ε-Ga₂O₃ thin film.

[0071] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0072] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a gallium oxide thin film, characterized in that, The method includes: A gallium oxide ceramic target is provided, wherein the gallium oxide ceramic target includes any one of silicon-tin co-doped, zirconium-tin co-doped, and hafnium-tin co-doped materials, wherein the doping concentration of Sn atoms in the gallium oxide ceramic target is 0.5~1 mol%, and the doping concentrations of Si, Zr, and Hf atoms are all greater than 0 and less than or equal to 1 mol%. After cleaning, the substrate is placed in the deposition chamber. The distance between the substrate and the gallium oxide ceramic target is adjusted, and the vacuum level of the deposition chamber is adjusted to 10. -5 Below Pa; The substrate is heated to 550~650℃ and held at that temperature. The temperature of the deposition chamber is kept constant, and a gallium oxide thin film is grown on the substrate surface using pulsed laser deposition technology; deposition parameters: oxygen pressure less than or equal to 40 mTorr; After the gallium oxide thin film is grown, it is annealed in situ in the deposition chamber to obtain the gallium oxide thin film; wherein, the same oxygen pressure as during deposition is maintained during annealing.

2. The preparation method according to claim 1, characterized in that, In the gallium oxide ceramic target, the doping concentration of Si atoms is 0.5~0.75 mol%, the doping concentration of Zr atoms is 0.5~0.75 mol%, and the doping concentration of Hf atoms is 0.5~0.75 mol%.

3. The preparation method according to claim 1, characterized in that, The substrate heating temperature is 600±30℃; or... The oxygen pressure is 1~30 mTorr.

4. The preparation method according to claim 1, characterized in that, The deposition parameters also include: laser energy density of 1~2.5 J / cm². 2 The pulsed laser frequency is 1~10Hz; or, The distance between the substrate and the gallium oxide ceramic target is 30~100mm.

5. The preparation method according to claim 1, characterized in that, The substrate is heated to 550-650°C at a heating rate of 5-30°C / min and held at that temperature for at least 20 minutes. When the gallium oxide thin film is annealed in situ in the deposition chamber, the cooling rate is 5~30℃ / min.

6. The preparation method according to any one of claims 1-5, characterized in that, The method further includes: before growing a gallium oxide thin film on the substrate surface using pulsed laser deposition technology, growing a buffer layer on the substrate surface under the same deposition conditions, and growing the gallium oxide thin film on the buffer layer facing away from the substrate surface; The buffer layer uses a gallium oxide ceramic target doped with 0.5 mol% Sn.

7. The preparation method according to claim 6, characterized in that, The method further includes: Pre-deposition was performed before growing the buffer layer and the gallium oxide film. The pre-deposition consisted of 100 pulses, with a 60-second interval, and was repeated 3 times. The pulse laser frequency was 2 Hz.

8. A gallium oxide thin film, characterized in that, The gallium oxide thin film is prepared by the preparation method according to any one of claims 1-7.

9. The gallium oxide thin film according to claim 8, characterized in that, The gallium oxide thin film is a single-phase ε-Ga2O3 thin film.

10. An application of the gallium oxide thin film according to claim 8 or 9, characterized in that, The gallium oxide thin film is used in electronic devices.

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