Beta-ligao2 epitaxial film and mocvd growth method thereof

Abstract

The application discloses a kind of β-LiGaO2 epitaxial film and MOCVD growth method thereof, its method includes the following steps: when the reaction chamber of MOCVD equipment is in first temperature interval and first pressure, substrate material is in situ surface pretreatment, to remove surface contaminant and reconstruct surface atomic arrangement;Reaction chamber is adjusted to second temperature interval, while introducing lithium precursor, gallium precursor and oxygen precursor, chemical vapor deposition is carried out under high oxygen atmosphere with VI / III ratio greater than 10:1, and β-LiGaO2 epitaxial film is grown on the surface of substrate material;Wherein, first temperature interval includes 300-500 DEG C;First pressure interval includes 10-100mbar;Second temperature interval includes 750-1000 DEG C.The application is particularly suitable for preparing β-LiGaO2 thin film with excellent piezoelectric properties and lattice matching characteristics.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material preparation technology, and in particular to a β-LiGaO2 epitaxial film and its MOCVD growth method. Background Technology

[0002] β-LiGaO2 (β-LG) is a non-centrosymmetric orthorhombic multifunctional material, often considered a group III-VI compound semiconductor. Benefiting from its excellent lattice matching with GaN, as well as its good chemical and thermal stability, β-LiGaO2 is widely regarded as one of the ideal substrate materials for preparing high-quality GaN epitaxial layers. It also possesses excellent piezoelectric and pyroelectric properties, making it valuable in microelectronics and optoelectronic integration, particularly in the highly specialized fields of all-solid-state deep ultraviolet lasers and high-performance ultraviolet phosphors, where it is an indispensable key material.

[0003] Currently, the preparation of β-LiGaO2 single crystals mainly relies on the Czochralski method or the crucible lowering method. However, these bulk growth techniques have limitations such as long growth cycles, high costs, and difficulties in thickness control. Although pulsed laser deposition (PLD) and molecular beam epitaxy (MBE) have been attempted for the preparation of β-LG thin films, they still face challenges such as excessively high growth temperatures, poor phase purity (easily induced by Li volatilization leading to impurities such as Ga2O3 or amorphization), and insufficient crystal quality. In the synthesis of lithium-containing compounds, traditional MOCVD technology is often limited by the high reactivity and volatility of lithium sources and the difficulty in precursor selection, making it difficult to stably obtain a single β-LiGaO2 phase at high temperatures. Specifically, the high decomposition activation energy of lithium and gallium metal organic sources leads to insufficient pyrolysis at low temperatures, and residual carbon impurities are embedded in the lattice to form deep-level defects, which aggravates device leakage. Although high temperature can effectively reduce the background carbon concentration of the thin film by 1-2 orders of magnitude through carrier gas purging, it aggravates the volatilization of lithium, induces lithium vacancies or stoichiometric imbalance, thereby deteriorating the conductivity of the thin film and causing multiphase coexistence.

[0004] Patent document CN119507044B discloses an epitaxial growth method for ultrawide bandgap lithium gallium oxide epitaxial films, which grows P-type LiGa5O8 epitaxial films on the substrate surface by MOCVD. However, this method is for LiGa5O8 materials and does not solve the problem of pure phase growth of β-LiGaO2 (orthorhombic crystal system).

[0005] Therefore, it is of great urgency to develop an improved MOCVD epitaxial process to achieve lithium loss suppression and precise control of stoichiometry at high temperatures, thereby obtaining large-size, high-phase-purity, and excellent-crystallization β-LiGaO2 epitaxial films. Summary of the Invention

[0006] Based on this, this application provides a β-LiGaO2 epitaxial film and its MOCVD growth method, aiming to overcome the problems in the prior art where it is difficult to obtain pure phase β-LiGaO2 due to excessively high preparation temperature, and the problem that lithium element is easily volatilized at high temperatures, leading to deviation of the stoichiometry of the film and a decrease in crystal quality.

[0007] To achieve the above objectives, the present invention provides the following technical solution: On one hand, the present invention provides a method for MOCVD growth of β-LiGaO2 epitaxial films, comprising the following steps: When the reaction chamber of the MOCVD equipment is in the first temperature range and the first pressure, the substrate material is subjected to in-situ surface pretreatment to remove surface contaminants and reconstruct the surface atomic arrangement. The reaction chamber was adjusted to the second temperature range, and lithium precursor, gallium precursor and oxygen precursor were introduced at the same time. Chemical vapor deposition was carried out in a high oxygen atmosphere with a VI / III ratio greater than 10:1 to grow a β-LiGaO2 epitaxial film on the substrate material surface. The first temperature range includes 300-500℃; the first pressure range includes 10-100mbar; and the second temperature range includes 750-1000℃. This temperature range can ensure the full thermal decomposition of the precursor and effectively suppress the excessive volatilization of lithium, which is the key window for the formation of a single β phase.

[0008] In some embodiments, the lithium precursor includes at least one of diethylzinc-doped bis(cyclopentadienyl)lithium, lithium tert-butoxide, or ethylcyclopentadienyllithium; the gallium precursor includes at least one of trimethylgallium, triethylgallium, or gallium chloride; and the oxygen precursor includes at least one of oxygen, ozone, water vapor, or nitrous oxide.

[0009] In some embodiments, the molar flow ratio of lithium precursor to gallium precursor is controlled between 1:1 and 1.2:1 to compensate for the volatilization loss of lithium and ensure that the stoichiometry of the film is Li:Ga=1:1.

[0010] In some embodiments, the substrate material includes at least one of magnesium oxide, spinel, aluminum oxide, silicon, silicon carbide, or gallium nitride.

[0011] In some implementations, the VI / III ratio is the molar ratio of oxygen to (lithium + gallium) between 10:1 and 200:1. The extremely high oxygen partial pressure helps to suppress the formation of oxygen vacancies and promotes the stable binding of lithium, preventing lithium vacancy defects.

[0012] In some embodiments, in-situ surface pretreatment includes thermal cleaning by introducing high-purity oxygen or hydrogen into a first temperature range for 10-30 minutes, with a first pressure between 30-60 mbar.

[0013] In some embodiments, the chemical vapor deposition time is 30-120 minutes, the initial pressure is between 30-60 mbar, and the VI / III ratio is maintained between 50:1 and 150:1.

[0014] On the other hand, the present invention discloses a β-LiGaO2 epitaxial film prepared by the above-mentioned MOCVD method based on β-LiGaO2 epitaxial film.

[0015] Furthermore, the β-LiGaO2 epitaxial film prepared by this invention has an orthorhombic crystal structure (Pna21, No.33), and its X-ray diffraction pattern shows no Ga2O3 impurity phase diffraction peaks, with a surface roughness Ra of less than 0.85 nm.

[0016] Furthermore, the thickness of the obtained β-LiGaO2 epitaxial film is 50-500 nm.

[0017] The β-LiGaO2 epitaxial film prepared by this invention has excellent piezoelectric properties and lattice matching characteristics, and is suitable for heteroepitaxial substrates of GaN-based devices or high-performance surface acoustic wave (SAW) devices.

[0018] In summary, the beneficial effects of this application are as follows: 1. High temperature and high crystallinity: By precisely controlling the reaction chamber temperature within the range of 750–1000℃ and performing epitaxial growth under a high oxygen partial pressure atmosphere, the lithium and gallium metal organic sources can be rapidly thermally decomposed, thereby suppressing the incorporation of carbon impurities into the crystal lattice and obtaining a thin film with high crystallinity.

[0019] 2. High phase purity control strategy: Using a precursor ratio of Li / Ga molar ratio of 1.0-1.2 and increasing the VI / III ratio to above 10, the orthorhombic β-LiGaO2 phase is effectively induced to dominate the growth, significantly reducing the formation probability of monoclinic α-LiGaO2 and gallium oxide impurity phases, thus achieving high phase purity of the thin film.

[0020] 3. Excellent epitaxial relationship: High-quality heteroepitaxial growth was successfully achieved on substrates represented by MgO or MgAl2O4, and the film surface exhibited atomic-level flatness (Ra<0.85nm), thus providing low-defect, high-flatness interface support for subsequent GaN epitaxial layers. Attached Figure Description

[0021] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof.

[0022] In the attached diagram: Figure 1This is a schematic diagram of the MOCVD growth method for β-LiGaO2 epitaxial films according to this application. Figure 2 A schematic diagram of the structure of an exemplary MOCVD equipment reaction chamber is shown. Figure 3 The X-ray diffraction (XRD) θ-2θ scan pattern of the β-LiGaO2 epitaxial film prepared in Example 1; Figure 4 The X-ray diffraction (XRD) θ-2θ scan pattern of the β-LiGaO2 epitaxial film prepared in Example 2; Figure 5 The X-ray diffraction (XRD) θ-2θ scan pattern of the β-LiGaO2 epitaxial film prepared in Example 3; Figure 6 Comparison of atomic force microscopy (AFM) morphology of β-LiGaO2 epitaxial films prepared in the three examples; Figure 7 This is an atomic force microscope (AFM) image of the β-LiGaO2 epitaxial film prepared in Example 1, taken from the forward scanning height. Figure 8 The X-ray diffraction (XRD) θ-2θ scan pattern of the β-LiGaO2 epitaxial film prepared in Comparative Example 1; Figure 9 This is an atomic force microscope (AFM) image of the β-LiGaO2 epitaxial film prepared in Comparative Example 1, taken from the forward direction.

[0023] Figure label annotations: 1. MOCVD equipment; 101. Reaction chamber; 102. Reaction gas channel; 103. Lithium precursor channel; 104. Gallium precursor channel; 105. Graphite tray; 106. Exhaust gas channel; 2. Substrate. Detailed Implementation

[0024] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects disclosed in this embodiment as detailed in the appended claims.

[0025] It should be noted that all directional indicators in the embodiments (such as up, down, left, right, front, back, etc.) are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0026] Furthermore, the use of terms such as "first" and "second" in the embodiments is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit this application. It is merely to distinguish components or operations described using the same technical terms and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0027] This invention utilizes MOCVD technology to achieve stable growth of β-LiGaO2 at relatively low temperatures. By employing highly active lithium and gallium sources and controlling the kinetics under an oxygen-rich atmosphere, the problems of lithium volatilization and impurity phase competition are successfully solved.

[0028] like Figure 2 As shown, the MOCVD equipment 1 used in this embodiment includes a reaction chamber 101 connected to three independent pipe passages: a reaction gas passage 102, a lithium precursor passage 103, and a gallium precursor passage 104. The substrate 2 is placed on a graphite tray 105 inside the reaction chamber 101 and heated. The oxygen precursor, lithium precursor, and gallium precursor enter the reaction chamber 101 from the three independent pipe passages, are fully mixed, and are deposited on the surface of the substrate 2. The exhaust gas is discharged from the exhaust gas passage 106 at the bottom of the reaction chamber 101.

[0029] like Figure 1 , Figure 2 As shown, the method in this application embodiment includes the following steps: Step S1, Substrate 2 Loading and Pretreatment: Place the cleaned substrate 2 on the graphite tray 105 of the MOCVD reaction chamber 101, and evacuate to the baseline vacuum level. Adjust the pressure of the reaction chamber 101 to the first pressure range (10-100 mbar, e.g., 50 mbar), and raise the temperature to the first temperature range (300-500℃, e.g., 400℃). Introduce high-purity oxygen or hydrogen through the reaction gas channel 102 for in-situ thermal cleaning to remove surface oxides and adsorbates for 10-30 minutes (e.g., 20 minutes for in-situ thermal cleaning with high-purity oxygen).

[0030] Step S2, Epitaxial Growth: Adjust the temperature of reaction chamber 101 to the second temperature range (750-1000℃, e.g., 750℃) and maintain a low-pressure environment. Simultaneously, open lithium precursor channel 103 to introduce lithium precursor (e.g., lithium tert-butoxide), gallium precursor channel 104 to introduce gallium precursor (e.g., TMGa), and reaction gas channel 102 to introduce oxygen precursor (e.g., oxygen). Control the Li / Ga molar flow ratio to the range of 1:1-1.2:1 (e.g., 1.1:1), and the O / (Li+Ga) molar flow ratio to the range of 10:1-200:1 (e.g., 50:1). Control the deposition growth time to the range of 30-120 minutes (e.g., 60 minutes) to obtain a β-LiGaO2 epitaxial film with high crystallinity on the surface of substrate 2.

[0031] The substrate 2 includes at least one of magnesium oxide, spinel, aluminum oxide, silicon, silicon carbide or gallium nitride, preferably a substrate material with a small lattice mismatch with β-LiGaO2, or is a homoepitaxial material. The lithium precursor includes at least one of diethylzinc-doped bis(cyclopentadienyl)lithium, lithium tert-butoxide, or ethylcyclopentadienyllithium; Gallium precursors include at least one of trimethylgallium, triethylgallium, or gallium chloride; Oxygen precursors include at least one of oxygen, ozone, water vapor, or nitrous oxide.

[0032] The β-LiGaO2 epitaxial film prepared by the method of the present application has an orthorhombic crystal structure, no Ga4O3 impurity phase diffraction peaks in its X-ray diffraction pattern, and a surface roughness Ra of less than 0.85 nm and a film thickness of 50-500 nm.

[0033] To further understand the content, features, and effects of this application, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings: Example 1 (β-LiGaO2 growth based on magnesium oxide substrate) In this embodiment, a β-LiGaO2 epitaxial film is grown on a (100) oriented magnesium oxide (MgO) single crystal substrate using a Stellar Oxide II MOCVD equipment manufactured by Suzhou Gallium Semiconductor Technology Co., Ltd. The specific steps are as follows: MgO single crystal with (100) orientation was selected as substrate 2 material. This orientation of MgO has good lattice matching with β-LiGaO2, which helps to reduce the stress at the epitaxial interface and reduce the defect density. It was cleaned by standard RCA cleaning process to thoroughly remove organic residues, particles and metal contaminants on the surface and obtain an atomically clean hydrophilic surface. The reaction chamber 101 of the MOCVD equipment 1 is adjusted to a low pressure of 50 mbar, with a background vacuum level better than 1E-3 mbar; the temperature of the reaction chamber 101 is adjusted to 500℃, and high-purity oxygen (O2) is introduced to perform in-situ heat treatment on the MgO substrate 2 for 20 minutes. The temperature of reaction chamber 101 was raised and stabilized at 900℃, and the pressure was maintained at a constant 50 mbar. Trimethylgallium (TMGa) was used as the gallium precursor, and its molar flow rate was controlled at 1.0E-5 mol / min. Bis(cyclopentadienyl)lithium (LiCp2) was used as the lithium precursor, and its molar flow rate was controlled at 1.1E-5 mol / min. The Li / Ga molar ratio was controlled at 1.1:1. Simultaneously, oxygen (O2) is introduced as the reaction gas, and the oxygen flow rate is adjusted so that the total molar ratio of O to (Li+Ga) is controlled at about 100:1. The deposition reaction is carried out for 60 minutes, and a β-LiGaO2 epitaxial film with a thickness of about 100 nm is obtained on the surface of substrate 2.

[0034] Example 2 (Heteroepitaxy growth based on spinel substrate) This embodiment involves growth on a (100) oriented spinel (MgAl2O4) substrate using a Stellar Oxide II MOCVD device manufactured by Suzhou Gallium Semiconductor Technology Co., Ltd. The specific steps are as follows: A (100) oriented MgAl2O4 single crystal was selected as substrate 2. This oriented MgAl2O4 has a good lattice match with β-LiGaO2, which is beneficial to relieve the stress at the heteroepitaxial interface and reduce the defect density. The reaction chamber 101 of the MOCVD equipment 1 was adjusted to a low pressure of 30 mbar. The temperature of the reaction chamber 101 was adjusted to 300°C, and hydrogen (H2) was introduced for 30 minutes of in-situ surface pretreatment to remove surface adsorbates and optimize surface activity. The temperature of reaction chamber 101 was adjusted to 1000℃, and the pressure was maintained at 30 mbar. Triethylgallium (TEGa) was selected as the gallium precursor, and lithium tert-butoxide was selected as the lithium precursor. The Li / Ga flow ratio was controlled at 1.05:1, and water vapor (H2O) was introduced as an oxidant. The total flow rate was controlled so that the O / (Li+Ga) molar ratio was approximately 120:1, and the deposition time was 90 minutes. A β-LiGaO2 epitaxial film with a thickness of approximately 100 nm was formed on the surface of substrate 2.

[0035] Example 3 (Heteroepitaxy growth based on sapphire (Al2O3) substrate) This embodiment involves growth on a sapphire (Al2O3) substrate using a Stellar Oxide I MOCVD device manufactured by Suzhou Gallium Semiconductor Technology Co., Ltd. The specific steps are as follows: (0001) oriented sapphire (Al2O3) was selected as substrate 2. The lattice mismatch between Al2O3 and β-LiGaO2 is small, which is beneficial to reducing interfacial stress. Substrate 2 was placed in MOCVD reaction chamber 101. The temperature of reaction chamber 101 was adjusted to 350℃ and the pressure of reaction chamber 101 was controlled at 30mbar. Oxygen (O2) was introduced for 30 minutes of in-situ annealing and cleaning, which effectively removed residual organic matter and volatile impurities on the substrate surface through high-temperature oxidation. The temperature of reaction chamber 101 was raised to 750℃ (second temperature) and the pressure was maintained at 30mbar. Trimethylgallium (TMGa) was used as gallium precursor and lithium tert-butoxide was used as lithium precursor. The Li / Ga flow ratio was controlled to be 1.05:1, and oxygen (O2) was introduced as oxidant. The total flow rate was controlled so that the O / (Li+Ga) molar ratio was about 140:1. After deposition for 90 minutes, a β-LiGaO2 epitaxial film with a thickness of about 140nm was obtained on the surface of substrate 2.

[0036] Detection results of the prepared β-LiGaO2 epitaxial film The β-LiGaO2 epitaxial films prepared in Examples 1, 2, and 3 were tested respectively to obtain... Figures 3-7 Data charts, in which, Figure 3 , Figure 4 , Figure 5 The XRD patterns of the samples obtained in Examples 1, 2, and 3 are shown below. Figure 6 These are comparison images of the AFM height morphology of the samples obtained in the three examples. Figure 7 This is an AFM forward scan height topography image of the sample obtained in Example 1.

[0037] like Figure 3 , Figure 4 , Figure 5 As shown, the X-ray diffraction (XRD) patterns of the β-LiGaO2 epitaxial films prepared in the three examples all show characteristic diffraction peaks belonging to the β-LiGaO2 (101) crystal plane near 2θ≈36°. The full spectrum diffraction signals can all be indexed as orthorhombic β-LiGaO2. No obvious Ga2O3 or amorphous dispersion was detected, that is, the film is mainly composed of a single β phase with extremely low impurity phase content, indicating that the prepared β-LiGaO2 epitaxial film has an orthorhombic crystal structure with high phase purity.

[0038] Figure 6 The images show atomic force microscopy (AFM) surface morphology images of the β-LiGaO2 epitaxial films prepared in the three examples. From left to right, they represent the detection data of the samples prepared in Example 1, Example 2, and Example 3, respectively. Figure 6As shown, the surface roughness Ra of the sample in Example 1 is 0.83 nm, the surface roughness Ra of the sample in Example 2 is 0.67 nm, and the surface roughness Ra of the sample in Example 3 is 0.63 nm. The surface roughness (Ra) of all three samples is less than 0.85 nm. Figure 7 This is an atomic force microscope (AFM) forward scanning height morphology image of the β-LiGaO2 epitaxial film prepared in Example 1, as shown below. Figure 7 As shown, the film surface exhibits a clear step-flow mode, indicating that the obtained material is a high-quality β-LiGaO2 epitaxial film with atomically flat surface.

[0039] Comparative Example 1 (Heteroepitaxy growth based on sapphire (Al2O3) substrate) This comparative example was grown on a sapphire (Al2O3) substrate using a Stellar Oxide I MOCVD device manufactured by Suzhou Gallium Semiconductor Technology Co., Ltd. The specific steps are as follows: (0001) oriented sapphire (Al2O3) was selected as substrate 2 and placed in MOCVD reaction chamber 101; the temperature of reaction chamber 101 was adjusted to 350℃ and the pressure of reaction chamber 101 was controlled to 30mbar; oxygen (O2) was introduced for in-situ annealing and cleaning for 30 minutes; the temperature of reaction chamber 101 was raised to 750℃ (second temperature) and the pressure was maintained at 30mbar; trimethylgallium (TMGa) was used as gallium precursor and lithium tert-butoxide was used as lithium precursor; the Li / Ga flow ratio was controlled to be 1.05:1, oxygen (O2) was introduced as oxidant, and the total flow rate was controlled so that the O / (Li+Ga) molar ratio was about 5:1. After deposition for 90 minutes, a β-LiGaO2 epitaxial film sample with a thickness of about 140nm was obtained on the surface of substrate 2.

[0040] The test results of the comparative sample are as follows: Figure 8 , Figure 9 As shown. Among them, Figure 8 The X-ray diffraction (XRD) pattern of the comparative sample shows that the (001) crystal plane diffraction peak of the β-LiGaO2 phase in the sample is sharp and has the highest intensity, indicating that the crystal plane has good crystal orientation; however, there is a significant diffuse scattering background at the bottom of the pattern, and obvious impurity phase diffraction peaks appear in the range of 2θ = 36° to 38°, confirming that the sample contains more amorphous components and trace impurities, resulting in a low overall crystallinity of the film.

[0041] Figure 9 The image shows the atomic force microscopy (AFM) topography of the comparative sample. Topography analysis shows that the sample has high surface roughness (Ra = 15.7 nm), severe undulation (Rpv = 169.6 nm), and local particles or protrusions, indicating that the sample surface has low smoothness.

[0042] The above results demonstrate that without an oxygen-rich environment and appropriate temperature control, it is difficult to obtain a single β-LiGaO2 phase epitaxial film with good crystallization and a smooth surface. This confirms the importance of an oxygen-rich environment and temperature control in the growth of single β-LiGaO2 phase epitaxial films.

[0043] In summary, this invention successfully prepared high-crystallinity β-LiGaO2 epitaxial films at temperatures lower than those of traditional solid-state reactions by selecting specific lithium / gallium organic sources and combining them with a high oxygen partial pressure MOCVD process, thus solving the technical challenges of lithium volatilization and impurity phase control.

[0044] Finally, it should be noted that the above disclosure is merely a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. The scope of this application is limited only by the appended claims.

Claims

1. A method for MOCVD growth of β-LiGaO2 epitaxial films, characterized in that: Includes the following steps: When the reaction chamber of the MOCVD equipment is in the first temperature range and the first pressure, the substrate material is subjected to in-situ surface pretreatment to remove surface contaminants and reconstruct the surface atomic arrangement. The reaction chamber is adjusted to the second temperature range, and lithium precursor, gallium precursor and oxygen precursor are introduced at the same time. Chemical vapor deposition is performed in a high oxygen atmosphere with a VI / III ratio greater than 10:1 to grow a β-LiGaO2 epitaxial film on the substrate material surface. The first temperature range includes 300-500℃; the first pressure range includes 10-100mbar; and the second temperature range includes 750-1000℃.

2. The MOCVD growth method for β-LiGaO2 epitaxial films according to claim 1, characterized in that: The lithium precursor includes at least one of diethylzinc-doped bis(cyclopentadienyl)lithium, lithium tert-butoxide, or ethylcyclopentadienyllithium; the gallium precursor includes at least one of trimethylgallium, triethylgallium, or gallium chloride; and the oxygen precursor includes at least one of oxygen, ozone, water vapor, or nitrous oxide.

3. The MOCVD growth method for β-LiGaO2 epitaxial films according to claim 1, characterized in that: The molar flow ratio of the lithium precursor to the gallium precursor is controlled between 1:1 and 1.2:

1.

4. The MOCVD growth method for β-LiGaO2 epitaxial films according to claim 1, characterized in that: The substrate material includes at least one of magnesium oxide, spinel, aluminum oxide, silicon, silicon carbide, or gallium nitride.

5. The MOCVD growth method for β-LiGaO2 epitaxial films according to claim 1, characterized in that: The VI / III ratio is the molar ratio of oxygen to the sum of lithium and gallium, and is between 10:1 and 200:

1.

6. The MOCVD growth method for β-LiGaO2 epitaxial films according to claim 1, characterized in that: The in-situ surface pretreatment includes hot cleaning by introducing high-purity oxygen or hydrogen into the first temperature range for 10-30 minutes, with the first pressure between 30-60 mbar.

7. The MOCVD growth method for β-LiGaO2 epitaxial films according to claim 1, characterized in that: The chemical vapor deposition time is 30-120 minutes, the first pressure is between 30-60 mbar, and the VI / III ratio is between 50:1 and 150:

1.

8. A β-LiGaO2 epitaxial film, characterized in that: It is prepared by the MOCVD growth method of a β-LiGaO2 epitaxial film according to any one of claims 1 to 7.

9. A β-LiGaO2 epitaxial film according to claim 8, characterized in that: The β-LiGaO2 epitaxial film has an orthorhombic crystal structure, and its X-ray diffraction pattern shows no Ga2O3 impurity phase diffraction peaks, with a surface roughness Ra of less than 0.85 nm.

10. A β-LiGaO2 epitaxial film according to claim 8, characterized in that: The thickness of the β-LiGaO2 epitaxial film is 50-500 nm.

Images