LiGa5O8 epitaxial film and preparation method and application thereof

Abstract

The invention discloses a LiGa5O8 epitaxial thin film and a preparation method and application thereof, and belongs to the technical field of semiconductors, LiGa5O8 precursor solution is atomized into liquid drops, the temperature is raised to 900-1000 DEG C under carrier gas, the liquid drops are subjected to thermal chemical reaction on the surface of a substrate, and the LiGa5O8 epitaxial thin film is obtained. The LiGa5O8 epitaxial thin film prepared by the method solves the problems of narrow forbidden band width and unstable physical and chemical properties of the existing p-type transparent oxide semiconductor, and is beneficial to promoting the development of oxide electronic devices. In addition, the method provided by the invention can be used for preparing the LiGa5O8 epitaxial film in a safe, environment-friendly and low-cost manner.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a LiGa5O8 epitaxial thin film and a preparation method and application thereof. Background Art

[0002] Transparent oxide semiconductor, or TOS, is a conductive semiconductor with a wide band gap and is transparent in visible light. Transparent oxide semiconductors have great potential in light-emitting diodes, solar cells, touch panels, transparent thin-film transistors, and other fields.

[0003] There are many types of n-type transparent oxide semiconductors, including ~In2O3, Ga2O3, ZnO, IGZO, ITO, etc., which have excellent performance and good stability, while there are fewer types of p-type transparent oxide semiconductors, including ~Cu2O, SnO, NiO, etc., which have average performance and poor stability. For example, Cu2O has a narrow band gap of only 2.0 eV, and its thin film transistor, i.e. TFT, has a very low mobility of only 1. cm 2 / (V·s). The direct band gap of SnO is about 3 eV, but the indirect band gap is only 0.7 eV, and its field effect mobility is very low, only 2.4 cm 2 / (V·s), more importantly, Sn in SnO 2+ Easily oxidized to Sn 4+ It can be seen that the existing p-type transparent oxide semiconductors have the problems of narrow bandgap and unstable physical and chemical properties. Summary of the invention

[0004] The present invention provides a LiGa5O8 epitaxial film and a preparation method and application thereof, which effectively solve the technical problems of narrow bandgap and unstable physical and chemical properties of existing p-type transparent oxide semiconductors. The present invention atomizes a LiGa5O8 precursor solution into droplets, and subjecting the droplets to a thermochemical reaction on a substrate surface under a carrier gas, thereby obtaining a LiGa5O8 epitaxial film with a wide bandgap and stable physical and chemical properties.

[0005] The first object of the present invention is to provide a method for preparing a LiGa5O8 epitaxial thin film, comprising the following steps: A LiGa5O8 precursor solution is prepared by taking a lithium precursor and a gallium precursor as raw materials.

[0006] The LiGa5O8 precursor solution is atomized into droplets, and the temperature is raised to 900°C-1000°C under a carrier gas. The droplets undergo a thermochemical reaction on the surface of the substrate. The lithium precursor reacts to generate Li2O, the gallium precursor reacts to generate Ga2O3, and Li2O and Ga2O3 react to generate LiGa5O8, thereby obtaining a LiGa5O8 epitaxial film.

[0007] As a preferred embodiment, the preparation method of LiGa5O8 precursor solution comprises the following steps: + with Ga 3+ A lithium precursor solution and a gallium precursor solution, both of which have a concentration of 0.01 mol / L to 0.1 mol / L, are mixed at a molar ratio of 1:2 to 5 to obtain a LiGa5O8 precursor solution.

[0008] As a preferred embodiment, the lithium precursor is lithium acetoacetate or lithium acetylacetonate, and the gallium precursor is gallium acetylacetonate or gallium chloride.

[0009] As a preferred embodiment, the carrier gas is nitrogen, argon or oxygen with a flow rate of 1000 mL / min to 11000 mL / min.

[0010] As a preferred embodiment, the thermochemical reaction time is 30 min to 120 min.

[0011] As a preferred embodiment, the atomization is performed by using an ultrasonic atomization chemical vapor deposition device, and the frequency of the atomization plate in the ultrasonic atomization chemical vapor deposition device is 1.7 MHz to 3 MHz.

[0012] As a preferred embodiment, the substrate is selected from Al2O3 substrate, LiTaO3 substrate, LiNbO3 substrate, GaN substrate, AlN substrate, SiC substrate, YSZ substrate, MgO substrate, STO substrate, NiO substrate, ITO substrate, β-Ga2O3 substrate or SnO2 substrate.

[0013] The second object of the present invention is to provide a LiGa5O8 epitaxial film, which is prepared by the above-mentioned preparation method, and the thickness of the LiGa5O8 epitaxial film is 0.6μm~1.2μm.

[0014] The third object of the present invention is to provide an application of the above-mentioned LiGa5O8 epitaxial film in optoelectronic devices.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a LiGa5O8 epitaxial film, wherein a lithium precursor and a gallium precursor are used as raw materials to prepare a LiGa5O8 precursor solution; the LiGa5O8 precursor solution is atomized into droplets, and the droplets react thermochemically on the surface of a substrate under a carrier gas, wherein the lithium precursor reacts to generate Li2O, and the gallium precursor reacts to generate Ga2O3, and simultaneously Li2O and Ga2O3 react to generate LiGa5O8, thereby obtaining a LiGa5O8 epitaxial film. The LiGa5O8 epitaxial film prepared by the present invention solves the problems of narrow bandgap and unstable physical and chemical properties of existing p-type transparent oxide semiconductors, and is helpful to promote the development of oxide electronic devices. In addition, the method provided by the present invention can prepare a LiGa5O8 epitaxial film safely, environmentally friendly and at low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of a vertical hot wall type ultrasonic atomization chemical vapor deposition device adopted by the present invention.

[0017] Description of reference numerals: 1. Ultrasonic atomizer, 2. Argon gas inlet of atomizer tank, 3. Oxygen gas inlet of atomizer tank, 4. Atomizer tank, 5. Gas outlet of atomizer tank, 6. Gas inlet at the bottom of reaction chamber, 7. Gas outlet at the bottom of reaction chamber, 8. Funnel, 9. Substrate, 10. Tray, 11. Reaction chamber, 12. Resistance wire, 13. Gas outlet of argon gas pipeline, 14. Gas outlet of oxygen pipeline.

[0018] Figure 2 This is the XRD θ-2θ scanning image of the LiGa5O8 epitaxial film prepared in Examples 1 to 3 of the present invention.

[0019] Figure 3 This is the XRD θ-2θ scanning image of the epitaxial film prepared in Comparative Examples 1 and 2 of the present invention.

[0020] Figure 4 This is the transmission spectrum of the LiGa5O8 epitaxial film prepared in Example 1 of the present invention.

[0021] Figure 5 This is the transmission spectrum of the LiGa5O8 epitaxial film prepared in Example 2 of the present invention.

[0022] Figure 6 This is the transmission spectrum of the LiGa5O8 epitaxial film prepared in Example 3 of the present invention.

[0023] Figure 7 αhν is the LiGa5O8 epitaxial film prepared in Example 1 of the present invention 2 -hν relationship diagram.

[0024] Figure 8 αhν is the LiGa5O8 epitaxial film prepared in Example 2 of the present invention 2 -hν relationship diagram.

[0025] Fig. 9 αhν is the LiGa5O8 epitaxial film prepared in Example 3 of the present invention 2 -hν relationship diagram. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is further described below in conjunction with specific examples, but the examples are not intended to limit the present invention. The following test methods and detection methods, unless otherwise specified, are conventional methods; the reagents and raw materials, unless otherwise specified, are commercially available.

[0027] Aiming at the technical problems of narrow bandgap and unstable physical and chemical properties of existing p-type transparent oxide semiconductors, the present invention provides a LiGa5O8 epitaxial thin film and a preparation method and application thereof. It should be noted that the present invention adopts Figure 1 The ultrasonic atomization chemical vapor deposition device shown is used to prepare LiGa5O8 epitaxial thin film.

[0028] The technical solution of the present invention is described in detail below.

[0029] The present invention provides a method for preparing a LiGa5O8 epitaxial thin film, comprising the following steps: S1, using a lithium precursor and a gallium precursor as raw materials to prepare a LiGa5O8 precursor solution.

[0030] S2, placing the substrate in acetone, ethanol, and deionized water for ultrasonic cleaning in sequence, then blowing high-purity nitrogen gas on the surface of the substrate, and mounting the cleaned substrate on the tray 10 in the reaction chamber 11.

[0031] S3, such as Figure 1As shown, the LiGa5O8 precursor solution is poured into the atomizing tank 4, the pipeline is connected, and the atomizing tank 4 is sealed; the distance between the tray 10 and the funnel 8 is adjusted; the temperature of the reaction chamber 11 is raised to 900°C~1000°C, and the temperature is kept, and the carrier gas is passed into the reaction chamber 11, so that the carrier gas fills the reaction chamber 11, and the excess air is discharged; the LiGa5O8 precursor solution is atomized into droplets, and the droplets are transported to the reaction chamber 11 by the carrier gas, and a thermochemical reaction occurs on the substrate surface of the tray 10, the lithium precursor reacts to generate Li2O, the gallium precursor reacts to generate Ga2O3, and Li2O and Ga2O3 react to generate LiGa5O8, stop atomization, stop passing the carrier gas, stop heating, wait for the ultrasonic atomization chemical vapor deposition device to cool to room temperature, take out the substrate, and obtain a LiGa5O8 epitaxial film.

[0032] In the above technical scheme, a LiGa5O8 precursor solution prepared by a lithium precursor and a gallium precursor is atomized into droplets. At high temperature, water molecules in the droplets are used to provide an oxygen source. The lithium precursor reacts with the oxygen source to generate Li2O, and the gallium precursor reacts with the oxygen source to generate Ga2O3. At the same time, Li2O and Ga2O3 react to generate LiGa5O8, thereby obtaining a LiGa5O8 epitaxial film. The LiGa5O8 epitaxial film has a wide bandgap and stable physical and chemical properties.

[0033] In order to obtain a LiGa5O8 precursor solution, the preparation method of the LiGa5O8 precursor solution comprises the following steps: + with Ga 3+ A lithium precursor solution and a gallium precursor solution, both of which have a concentration of 0.01 mol / L to 0.1 mol / L, are mixed at a molar ratio of 1:2 to 5 to obtain a LiGa5O8 precursor solution.

[0034] It should be noted that the lithium precursor used in the present invention is lithium acetoacetate or lithium acetylacetonate, and the gallium precursor is gallium acetylacetonate or gallium chloride.

[0035] In order to ensure that the atomized droplets form a LiGa5O8 epitaxial film on the substrate surface, the carrier gas is nitrogen, argon or oxygen with a flow rate of 1000mL / min~11000mL / min. When oxygen is used as the carrier gas, the lithium precursor and the gallium precursor are subjected to a thermochemical reaction, and LiGa5O8 with better yield and purity is obtained under the condition of sufficient oxygen source.

[0036] In order to form a LiGa5O8 epitaxial thin film through a thermochemical reaction of the atomized droplets, the time of the thermochemical reaction is 30 minutes to 120 minutes.

[0037] In order to atomize the LiGa5O8 precursor solution into droplets, the atomization is performed using an ultrasonic atomization chemical vapor deposition device, and the frequency of the atomization plate in the ultrasonic atomization chemical vapor deposition device is 1.7MHz~3MHz.

[0038] It should be noted that the substrate used in the present invention is selected from Al2O3 substrate, LiTaO3 substrate, LiNbO3 substrate, GaN substrate, AlN substrate, SiC substrate, YSZ substrate, MgO substrate, STO substrate, NiO substrate, ITO substrate, β-Ga2O3 substrate or SnO2 substrate.

[0039] The present invention is specifically described below by means of the following examples and comparative examples.

[0040] Example 1 A method for preparing a LiGa5O8 epitaxial thin film comprises the following steps: S1. Prepare a lithium acetoacetate solution with a concentration of 0.05 mol / L and a volume of 20 mL: use an electronic balance to weigh 0.10802 g of lithium acetoacetate and put it into a beaker, add 20 mL of deionized water to the beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the lithium acetoacetate solution is clear and transparent and there is no solid drug residue, to obtain a lithium precursor solution.

[0041] S2. Prepare a gallium acetylacetonate solution with a concentration of 0.05 mol / L and a volume of 100 mL: use an electronic scale to weigh 1.83525 g of gallium acetylacetonate and put it into a beaker, add 100 mL of deionized water and 1.5 mL of hydrochloric acid to the beaker in order to promote the dissolution of the gallium acetylacetonate, add a magnet, place the beaker on a magnetic stirrer, and stir until the gallium acetylacetonate solution is clear and transparent with no solid drug residue, to obtain a gallium precursor solution.

[0042] S3, prepare a LiGa5O8 precursor solution with a concentration of 0.05 mol / L and a volume of 120 mL: put 20 mL of lithium acetoacetate solution and 100 mL of gallium acetylacetonate solution into a beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the LiGa5O8 precursor solution becomes clear and transparent to obtain a LiGa5O8 precursor solution.

[0043] S4, ultrasonically clean the c-plane sapphire substrate in acetone for 5 minutes to remove organic contamination, then ultrasonically clean it in ethanol for 5 minutes to remove acetone, then ultrasonically clean it in deionized water for 5 minutes to remove ethanol, then purge the surface of the substrate with high-purity nitrogen to clean it, and mount the cleaned c-plane sapphire substrate on the tray 10 in the reaction chamber 11.

[0044] S5, pour 120mL LiGa5O8 precursor solution into the atomizer 4, connect the argon pipe outlet 13 to the argon inlet 2 of the atomizer, connect the oxygen pipe outlet 14 to the oxygen inlet 3 of the atomizer, connect the atomizer outlet 5 to the bottom inlet 6 of the reaction chamber, seal the atomizer 4, connect the funnel 8 to the bottom outlet 7 of the reaction chamber, adjust the distance between the substrate 9 and the funnel 8 on the tray 10 to 10mm, seal the reaction chamber 11, start heating, heat the reaction chamber 11 to 900℃, and keep it warm for 15min, start ventilation, pass argon gas with a flow rate of 11000mL / min into the reaction chamber 11, set the time to 15min, fill the reaction chamber 11 with argon gas, and discharge excess air.

[0045] S6, start atomization, convert the LiGa5O8 precursor solution into atomized droplets through the ultrasonic atomizer 1, and then the atomized droplets are transported to the reaction chamber 11 by argon gas, and a thermochemical reaction is carried out at 900°C for 60 minutes, then stop atomization, stop ventilation, stop heating, wait for the ultrasonic atomization chemical vapor deposition device to cool to room temperature, take out the c-plane sapphire substrate, and obtain the LiGa5O8 epitaxial film.

[0046] Example 2 A method for preparing a LiGa5O8 epitaxial thin film comprises the following steps: S1. Prepare a lithium acetoacetate solution with a concentration of 0.05 mol / L and a volume of 20 mL: use an electronic balance to weigh 0.10802 g of lithium acetoacetate and put it into a beaker, add 20 mL of deionized water to the beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the lithium acetoacetate solution is clear and transparent and there is no solid drug residue, to obtain a lithium precursor solution.

[0047] S2. Prepare a gallium acetylacetonate solution with a concentration of 0.05 mol / L and a volume of 100 mL: use an electronic scale to weigh 1.83525 g of gallium acetylacetonate and put it into a beaker, add 100 mL of deionized water and 1.5 mL of hydrochloric acid to the beaker in order to promote the dissolution of the gallium acetylacetonate, add a magnet, place the beaker on a magnetic stirrer, and stir until the gallium acetylacetonate solution is clear and transparent with no solid drug residue, to obtain a gallium precursor solution.

[0048] S3, prepare a LiGa5O8 precursor solution with a concentration of 0.05 mol / L and a volume of 120 mL: put 20 mL of lithium acetoacetate solution and 100 mL of gallium acetylacetonate solution into a beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the LiGa5O8 precursor solution becomes clear and transparent to obtain a LiGa5O8 precursor solution.

[0049] S4, ultrasonically clean the c-plane sapphire substrate in acetone for 5 minutes to remove organic contamination, then ultrasonically clean it in ethanol for 5 minutes to remove acetone, then ultrasonically clean it in deionized water for 5 minutes to remove ethanol, then purge the surface of the substrate with high-purity nitrogen to clean it, and mount the cleaned c-plane sapphire substrate on the tray 10 in the reaction chamber 11.

[0050] S5, pour 120mL of LiGa5O8 precursor solution into the atomizer 4, connect the argon pipe outlet 13 to the argon inlet 2 of the atomizer, connect the oxygen pipe outlet 14 to the oxygen inlet 3 of the atomizer, connect the atomizer outlet 5 to the bottom inlet 6 of the reaction chamber, seal the atomizer 4, connect the funnel 8 to the bottom outlet 7 of the reaction chamber, adjust the distance between the substrate 9 on the tray 10 and the funnel 8 to 10mm, seal the reaction chamber 11, start heating, heat the reaction chamber 11 to 950℃, and keep it warm for 15min, start ventilation, pass argon gas at a flow rate of 11000mL / min into the reaction chamber 11, set the time to 15min, fill the reaction chamber 11 with argon gas, and exhaust excess air.

[0051] S6, start atomization, convert the LiGa5O8 precursor solution into atomized droplets through the ultrasonic atomizer 1, and then the atomized droplets are transported to the reaction chamber 11 by argon gas, and a thermochemical reaction is carried out at 900°C for 60 minutes, then stop atomization, stop ventilation, stop heating, wait for the ultrasonic atomization chemical vapor deposition device to cool to room temperature, take out the c-plane sapphire substrate, and obtain the LiGa5O8 epitaxial film.

[0052] Example 3 A method for preparing a LiGa5O8 epitaxial thin film comprises the following steps: S1. Prepare a lithium acetoacetate solution with a concentration of 0.05 mol / L and a volume of 40 mL: use an electronic balance to weigh 0.21604 g of lithium acetoacetate and put it into a beaker, add 40 mL of deionized water to the beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the lithium acetoacetate solution is clear and transparent and there is no solid drug residue, to obtain a lithium precursor solution.

[0053] S2. Prepare a gallium acetylacetonate solution with a concentration of 0.05 mol / L and a volume of 80 mL: use an electronic scale to weigh 1.4682 g of gallium acetylacetonate and put it into a beaker, add 80 mL of deionized water and 1.2 mL of hydrochloric acid to the beaker in turn to promote the dissolution of the gallium acetylacetonate, add a magnet, place the beaker on a magnetic stirrer, and stir until the gallium acetylacetonate solution is clear and transparent with no solid drug residue, to obtain a gallium precursor solution.

[0054] S3, prepare a LiGa5O8 precursor solution with a concentration of 0.05 mol / L and a volume of 120 mL: put 40 mL of lithium acetoacetate solution and 80 mL of gallium acetylacetonate solution into a beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the LiGa5O8 precursor solution becomes clear and transparent to obtain a LiGa5O8 precursor solution.

[0055] S4, ultrasonically clean the c-plane sapphire substrate in acetone for 5 minutes to remove organic contamination, then ultrasonically clean it in ethanol for 5 minutes to remove acetone, then ultrasonically clean it in deionized water for 5 minutes to remove ethanol, then purge the surface of the substrate with high-purity nitrogen to clean it, and mount the cleaned c-plane sapphire substrate on the tray 10 in the reaction chamber 11.

[0056] S5, pour 120mL LiGa5O8 precursor solution into the atomizer 4, connect the argon pipe outlet 13 to the argon inlet 2 of the atomizer, connect the oxygen pipe outlet 14 to the oxygen inlet 3 of the atomizer, connect the atomizer outlet 5 to the bottom inlet 6 of the reaction chamber, seal the atomizer 4, connect the funnel 8 to the bottom outlet 7 of the reaction chamber, adjust the distance between the substrate 9 and the funnel 8 on the tray 10 to 10mm, seal the reaction chamber 11, start heating, heat the reaction chamber 11 to 900℃, and keep it warm for 15min, start ventilation, pass argon gas with a flow rate of 11000mL / min into the reaction chamber 11, set the time to 15min, fill the reaction chamber 11 with argon gas, and discharge excess air.

[0057] S6, start atomization, convert the LiGa5O8 precursor solution into atomized droplets through the ultrasonic atomizer 1, and then the atomized droplets are transported to the reaction chamber 11 by argon gas, and a thermochemical reaction is carried out at 900°C for 60 minutes, then stop atomization, stop ventilation, stop heating, wait for the ultrasonic atomization chemical vapor deposition device to cool to room temperature, take out the c-plane sapphire substrate, and obtain the LiGa5O8 epitaxial film.

[0058] In order to further illustrate the effect of the present invention, the present invention also sets a comparative example, as follows: Comparative Example 1 Compared with Example 1, the difference is that Li + with Ga 3+ The molar ratio was adjusted from 1:5 to 1:1.

[0059] A method for preparing a LiGa5O8 epitaxial thin film comprises the following steps: S1. Prepare a lithium acetoacetate solution with a concentration of 0.05 mol / L and a volume of 60 mL: use an electronic balance to weigh 0.32406 g of lithium acetoacetate and put it into a beaker, add 60 mL of deionized water to the beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the lithium acetoacetate solution is clear and transparent and there is no solid drug residue, to obtain a lithium precursor solution.

[0060] S2. Prepare a gallium acetylacetonate solution with a concentration of 0.05 mol / L and a volume of 60 mL: use an electronic scale to weigh 1.10115 g of gallium acetylacetonate and put it into a beaker, add 60 mL of deionized water and 0.9 mL of hydrochloric acid to the beaker in sequence to promote the dissolution of the gallium acetylacetonate, add a magnet, place the beaker on a magnetic stirrer, and stir until the gallium acetylacetonate solution is clear and transparent and there is no solid drug residue, to obtain a gallium precursor solution.

[0061] S3, prepare a LiGa5O8 precursor solution with a concentration of 0.05 mol / L and a volume of 120 mL: put 60 mL of lithium acetoacetate solution and 60 mL of gallium acetylacetonate solution into a beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the LiGa5O8 precursor solution becomes clear and transparent to obtain a LiGa5O8 precursor solution.

[0062] S4, ultrasonically clean the c-plane sapphire substrate in acetone for 5 minutes to remove organic contamination, then ultrasonically clean it in ethanol for 5 minutes to remove acetone, then ultrasonically clean it in deionized water for 5 minutes to remove ethanol, then purge the surface of the substrate with high-purity nitrogen to clean it, and mount the cleaned c-plane sapphire substrate on the tray 10 in the reaction chamber 11.

[0063] S5, pour 120mL LiGa5O8 precursor solution into the atomizer 4, connect the argon pipe outlet 13 to the argon inlet 2 of the atomizer, connect the oxygen pipe outlet 14 to the oxygen inlet 3 of the atomizer, connect the atomizer outlet 5 to the bottom inlet 6 of the reaction chamber, seal the atomizer 4, connect the funnel 8 to the bottom outlet 7 of the reaction chamber, adjust the distance between the substrate 9 and the funnel 8 on the tray 10 to 10mm, seal the reaction chamber 11, start heating, heat the reaction chamber 11 to 900℃, and keep it warm for 15min, start ventilation, pass argon gas with a flow rate of 11000mL / min into the reaction chamber 11, set the time to 15min, fill the reaction chamber 11 with argon gas, and discharge excess air.

[0064] S6, start atomization, convert the LiGa5O8 precursor solution into atomized droplets through the ultrasonic atomizer 1, and then the atomized droplets are transported to the reaction chamber 11 by argon gas, and a thermochemical reaction is carried out at 900°C for 60 minutes, then stop atomization, stop ventilation, stop heating, wait for the ultrasonic atomization chemical vapor deposition device to cool to room temperature, take out the c-plane sapphire substrate, and obtain the LiGa5O8 epitaxial film.

[0065] Comparative Example 2 Compared with Example 1, the difference is that the temperature of the reaction chamber is reduced from 900°C to 800°C.

[0066] A method for preparing a LiGa5O8 epitaxial thin film comprises the following steps: S1. Prepare a lithium acetoacetate solution with a concentration of 0.05 mol / L and a volume of 20 mL: use an electronic balance to weigh 0.10802 g of lithium acetoacetate and put it into a beaker, add 20 mL of deionized water to the beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the lithium acetoacetate solution is clear and transparent and there is no solid drug residue, to obtain a lithium precursor solution.

[0067] S2. Prepare a gallium acetylacetonate solution with a concentration of 0.05 mol / L and a volume of 100 mL: use an electronic scale to weigh 1.83525 g of gallium acetylacetonate and put it into a beaker, add 100 mL of deionized water and 1.5 mL of hydrochloric acid to the beaker in order to promote the dissolution of the gallium acetylacetonate, add a magnet, place the beaker on a magnetic stirrer, and stir until the gallium acetylacetonate solution is clear and transparent with no solid drug residue, to obtain a gallium precursor solution.

[0068] S3, prepare a LiGa5O8 precursor solution with a concentration of 0.05 mol / L and a volume of 120 mL: put 20 mL of lithium acetoacetate solution and 100 mL of gallium acetylacetonate solution into a beaker, put in a magnet, place the beaker on a magnetic stirrer, and stir until the LiGa5O8 precursor solution becomes clear and transparent to obtain a LiGa5O8 precursor solution.

[0069] S4, ultrasonically clean the c-plane sapphire substrate in acetone for 5 minutes to remove organic contamination, then ultrasonically clean it in ethanol for 5 minutes to remove acetone, then ultrasonically clean it in deionized water for 5 minutes to remove ethanol, then purge the surface of the substrate with high-purity nitrogen to clean it, and mount the cleaned c-plane sapphire substrate on the tray 10 in the reaction chamber 11.

[0070] S5, pour 120mL LiGa5O8 precursor solution into the atomizer 4, connect the argon pipe outlet 13 with the argon inlet 2 of the atomizer, connect the oxygen pipe outlet 14 with the oxygen inlet 3 of the atomizer, connect the atomizer outlet 5 with the bottom inlet 6 of the reaction chamber, seal the atomizer 4, connect the funnel 8 with the bottom outlet 7 of the reaction chamber, adjust the distance between the substrate 9 and the funnel 8 on the tray 10 to 10mm, seal the reaction chamber 11, start heating, heat the reaction chamber 11 to 800℃, and keep it warm for 15min, start ventilation, pass argon gas with a flow rate of 11000mL / min into the reaction chamber 11, set the time to 15min, fill the reaction chamber 11 with argon gas, and discharge excess air.

[0071] S6, start atomization, convert the LiGa5O8 precursor solution into atomized droplets through the ultrasonic atomizer 1, and then the atomized droplets are transported to the reaction chamber 11 by argon gas, and a thermochemical reaction is carried out at 800°C for 60 minutes, then stop atomization, stop ventilation, stop heating, wait for the ultrasonic atomization chemical vapor deposition device to cool to room temperature, take out the c-plane sapphire substrate, and obtain the LiGa5O8 epitaxial film.

[0072] The performance of the LiGa5O8 epitaxial thin films provided in Examples 1 to 3 above was tested, and the results are as follows.

[0073] Figure 2 The XRD θ-2θ scanning images of the LiGa5O8 epitaxial thin films prepared in Examples 1 to 3 of the present invention are shown in FIG. Figure 2 It can be seen that: 2θ=18.8°, 38.2°, 58.8°, and 81.3° correspond to the diffraction peak positions of LiGa5O8 (111) crystal plane, (222) crystal plane, (333) crystal plane, and (444) crystal plane, respectively, which indicates that the single crystal LiGa5O8 epitaxial films prepared in Example 1, Example 2, and Example 3 are preferentially oriented along the {111} crystal plane family.

[0074] Figure 3 The XRD θ-2θ scanning images of the epitaxial films prepared in Comparative Examples 1 and 2 of the present invention are shown in Figure 1. The horizontal axis is twice the X-ray incident angle 2θ, and the vertical axis is the intensity. Figure 3It can be seen that 2θ=18.8°, 38.1°, 58.7°, and 81.3° correspond to the diffraction peak positions of LiGa5O8 (111), (222), (333), and (444) crystal planes, respectively, while 2θ=19.3°, 39.1°, 60.1°, and 83.5° correspond to the diffraction peak positions of κ-Ga2O3 (002), (004), (006), and (008) crystal planes, respectively. For the epitaxial film prepared in Comparative Example 1, its XRD pattern contains the diffraction peaks of κ-Ga2O3 and LiGa5O8 at the same time, which indicates that the epitaxial film prepared in Comparative Example 1 is an epitaxial film containing a mixed phase of κ-Ga2O3 and LiGa5O8, while the XRD pattern of the epitaxial film prepared in Comparative Example 2 also only contains the diffraction peak of κ-Ga2O3, so it is a κ-Ga2O3 epitaxial film. In summary, when the Li component in the LiGa5O8 precursor solution is excessive or the growth temperature of the epitaxial film in the reaction chamber during preparation is low, the single-phase LiGa5O8 epitaxial film cannot be successfully prepared.

[0075] Figure 4~Figure 6 The transmission spectra of the LiGa5O8 epitaxial films prepared in Examples 1 to 3 of the present invention are shown respectively. Figure 4~Figure 6 It can be seen that the average transmittance of the LiGa5O8 epitaxial films prepared in Example 1, Example 2, and Example 3 in the visible light range is greater than 75%, and has an obvious absorption cutoff edge in the ultraviolet region.

[0076] Figure 7~Figure 9 are respectively the αhν of the LiGa5O8 epitaxial films prepared in Examples 1 to 3 of the present invention 2 -hν relationship diagram. Figure 7~Figure 9 It can be seen that the optical band gaps of the LiGa5O8 epitaxial films prepared in Example 1, Example 2, and Example 3 are 5.02eV, 5.13eV, and 5.28eV, respectively. An increase in the growth temperature or an increase in the Li component in the precursor solution will increase the optical band gap, which indicates that the LiGa5O8 epitaxial films prepared in Example 1, Example 2, and Example 3 have an ultra-wide optical band gap.

[0077] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a LiGa5O8 epitaxial thin film, characterized in that: The following steps are involved: A LiGa5O8 precursor solution is prepared by using a lithium precursor and a gallium precursor as raw materials; The LiGa5O8 precursor solution is atomized into droplets, and the temperature is raised to 900°C-1000°C under a carrier gas. The droplets undergo a thermochemical reaction on the surface of the substrate. The lithium precursor reacts to generate Li2O, the gallium precursor reacts to generate Ga2O3, and Li2O and Ga2O3 react to generate LiGa5O8, thereby obtaining a LiGa5O8 epitaxial film.

2. The method for preparing a LiGa5O8 epitaxial thin film according to claim 1, characterized in that: The preparation method of LiGa5O8 precursor solution comprises the following steps: + with Ga 3+ The lithium precursor solution and the gallium precursor solution are mixed at a molar ratio of 1:2 to 5 to obtain a LiGa5O8 precursor solution.

3. The method for preparing a LiGa5O8 epitaxial thin film according to claim 1, characterized in that: The lithium precursor is lithium acetoacetate or lithium acetylacetonate, and the gallium precursor is gallium acetylacetonate or gallium chloride.

4. The method for preparing a LiGa5O8 epitaxial thin film according to claim 1, characterized in that: The carrier gas is nitrogen, argon or oxygen with a flow rate of 1000mL / min to 11000mL / min.

5. The method for preparing a LiGa5O8 epitaxial thin film according to claim 1, characterized in that: The time of the thermochemical reaction is 30 min to 120 min.

6. The method for preparing a LiGa5O8 epitaxial thin film according to claim 1, characterized in that: The atomization is performed by using an ultrasonic atomization chemical vapor deposition device, and the frequency of the atomization plate in the ultrasonic atomization chemical vapor deposition device is 1.7 MHz to 3 MHz.

7. The method for preparing a LiGa5O8 epitaxial thin film according to claim 1, characterized in that: The substrate is selected from Al2O3 substrate, LiTaO3 substrate, LiNbO3 substrate, GaN substrate, AlN substrate, SiC substrate, YSZ substrate, MgO substrate, STO substrate, NiO substrate, ITO substrate, β-Ga2O3 substrate or SnO2 substrate.

8. A LiGa5O8 epitaxial thin film, characterized in that: The LiGa5O8 epitaxial film is prepared by the preparation method according to any one of claims 1 to 7, and the thickness of the LiGa5O8 epitaxial film is 0.6μm~1.2μm.

9. Use of the LiGa5O8 epitaxial thin film according to claim 8 in optoelectronic devices.

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