MgGa2O4 epitaxial film and preparation method thereof
By using gallium acetylacetonate and magnesium acetate tetrahydrate as raw materials through atomized chemical vapor deposition, the safety hazards and high costs of MgGa2O4 epitaxial film growth have been solved, achieving low-cost, safe and environmentally friendly preparation of high-quality MgGa2O4 epitaxial films with precise control of stoichiometry.
Patent Information
- Application Number
- CN202512012161.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-03-31
AI Technical Summary
Existing methods for growing MgGa2O4 epitaxial thin films have safety hazards, high costs, and inaccurate stoichiometry. The MOCVD method uses flammable, explosive, and toxic raw materials and is costly, while the RFMS method is difficult to achieve standard stoichiometry.
A MgGa2O4 precursor solution was prepared by ultrasonic atomization chemical vapor deposition using gallium acetylacetonate and magnesium acetate tetrahydrate as raw materials. The solution was then reacted on a sapphire substrate at 550 °C, and the Mg2+/Ga3+ molar ratio was controlled to be 5:1 to prepare a MgGa2O4 epitaxial thin film.
This method achieves safe and environmentally friendly low-cost preparation, and precisely controls the stoichiometry of the thin film, thereby improving the crystallinity and performance of MgGa2O4 epitaxial thin films.
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Figure CN121760058A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, specifically to a MgGa2O4 epitaxial thin film and its preparation method. Background Technology
[0002] In recent years, solar-blind ultraviolet photodetectors have attracted widespread attention in fields such as missile early warning, flame monitoring, space secure communication, and environmental monitoring. Wide-bandgap semiconductor solar-blind ultraviolet photodetectors have gained particular interest in this field due to their advantages, including miniaturization, low power consumption, low cost, strong anti-interference capability, strong radiation resistance, high thermal stability, and high chemical stability. Compared to binary oxide semiconductors such as Ga₂O₃ and ZnO, ternary oxide semiconductors like MgGa₂O₄, with its dual cations, are easier to control in terms of optical, electrical, and photoelectric properties. The crystal structure of MgGa₂O₄ features a cubic close-packed oxygen ion configuration, with cations occupying 1 / 8 of the tetrahedral center position and 1 / 4 of the octahedral center position. Previous research has focused on MgGa₂O₄ as a luminescent material, achieving good luminescence performance through doping with elements such as Mn, Cr, and Eu. Only in recent years has the application potential of MgGa₂O₄ in the field of solar-blind ultraviolet photodetectors been discovered.
[0003] Currently, the main methods for growing MgGa2O4 epitaxial films are metal-organic chemical vapor deposition (MOCVD) and radio frequency magnetron sputtering (RFMS). Although MOCVD can produce MgGa2O4 epitaxial films with high crystal quality, the metal-organic sources used (p-methylmagnesium thiocene (Cp2Mg) and triethylgallium (TEGa)) are flammable, explosive, and toxic, posing safety hazards during the preparation process. Furthermore, the high cost of the equipment increases the overall growth cost of MgGa2O4 epitaxial films. Meanwhile, MgGa2O4 epitaxial films prepared by RFMS deviate significantly from the standard stoichiometry, thus reducing device performance. Summary of the Invention
[0004] This invention provides a MgGa2O4 epitaxial thin film and its preparation method. The MgGa2O4 epitaxial thin film prepared by this method solves the problem of high growth cost of MgGa2O4 epitaxial thin films prepared by MOCVD method, and also solves the problem that MgGa2O4 epitaxial thin films prepared by RFMS method are difficult to meet the standard stoichiometry. In addition, the preparation method of MgGa2O4 epitaxial thin film also solves the problems of unsafety and environmental protection of MOCVD method.
[0005] To solve the above-mentioned technical problems, the present invention provides a method for preparing MgGa2O4 epitaxial thin films, comprising the following steps: After cleaning, the substrate is placed inside the reaction chamber; Prepare gallium acetylacetone solution; Magnesium acetate tetrahydrate was added to a gallium acetylacetonate solution to prepare a 0.3 mol / L MgGa₂O₄ precursor solution, wherein the MgGa₂O₄ precursor solution contained Mg 2+ / Ga 3+ The molar ratio is 5:1; The prepared MgGa2O4 precursor solution was converted into atomized droplets by atomized chemical vapor deposition and transported to the reaction chamber by a carrier gas. The MgGa2O4 epitaxial film was prepared by chemical reaction on the substrate surface at 550°C.
[0006] Although MgGa2O4 precursor solution contains Mg 2+ / Ga 3+ The molar ratio was 5:1, but there was significant magnesium loss during growth, resulting in a low Mg content in the actual prepared film. 2+ / Ga 3+ The molar ratio is 1:2, which conforms to the standard stoichiometric ratio.
[0007] Below 550℃ (e.g., 500℃), Mg cannot be effectively incorporated into the film; above 550℃ (e.g., 700℃), Mg is severely lost, resulting in MgGa2O4 epitaxial films that fail to meet the standard stoichiometry (Mg²⁺ / Mg²⁺). 2 + / Ga 3+ The molar ratio is 1:2.
[0008] Preferably, the preparation steps of the gallium acetylacetonate solution are as follows: deionized water and hydrochloric acid are added to gallium acetylacetonate in sequence, and the solution is stirred until the gallium acetylacetonate dissolves and the solution becomes clear and transparent, thus obtaining the gallium acetylacetonate solution.
[0009] Preferably, the concentration of the gallium acetylacetonate solution is 0.05 mol / L.
[0010] If the concentration of the gallium acetylacetonate solution is too high (0.1 mol / L), the viscosity of the gallium acetylacetonate solution will be too high, which is not conducive to the formation of fine and uniform atomized droplets; the atomized droplet size will be too large, resulting in incomplete reaction; and the film growth rate will be too fast, leading to a decrease in crystal quality. If the concentration of the gallium acetylacetonate solution is too low (0.01 mol / L), the atomized droplet size will be too small, resulting in a decrease in growth efficiency; and the film growth rate will be too slow.
[0011] Preferably, the carrier gas is argon, and the carrier gas flow rate is 4000 mL / min.
[0012] When the carrier gas flow rate is >4000 mL / min, the surface of the MgGa2O4 epitaxial film grown on the substrate is rough and the thickness is uneven; when the carrier gas flow rate is <4000 mL / min, the MgGa2O4 epitaxial film grown on the substrate is thin and the growth rate is low.
[0013] Preferably, the MgGa2O4 precursor solution is atomized by ultrasonic atomization at a frequency of 2.4 MHz.
[0014] Preferably, the substrate is sapphire.
[0015] Sapphire was chosen as the substrate because it is inexpensive and readily available, and has a small lattice mismatch with MgGa2O4, which is beneficial for preparing high-quality MgGa2O4 thin films.
[0016] Preferably, the substrate is subjected to ultrasonic cleaning in acetone, ethanol, and deionized water in sequence, and then dried by purging with nitrogen.
[0017] Preferably, the reaction time is 60 min.
[0018] The present invention also provides a method for preparing MgGa2O4 epitaxial thin films.
[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for preparing MgGa2O4 epitaxial thin films provided in this invention uses gallium acetylacetonate and magnesium acetate tetrahydrate as reactants. Compared with the existing MOCVD method for preparing MgGa2O4 epitaxial thin films using metal-organic sources, this method uses low-toxicity, low-pollution raw materials and the preparation process is safe and environmentally friendly. Furthermore, the gallium acetylacetonate and magnesium acetate tetrahydrate used in this method are inexpensive and readily available. The atomized chemical vapor deposition method uses equipment with low maintenance costs and does not require a vacuum environment during growth, significantly reducing the growth cost of MgGa2O4 epitaxial thin films.
[0020] Compared to the MgGa2O4 epitaxial films prepared by RFMS, which deviate significantly from the standard stoichiometry, the atomized chemical vapor deposition method used in this invention can easily and directly adjust the Mg content in the precursor solution. 2+ / Ga 3+ The proportions are then used to precisely control the stoichiometry in the thin film. Attached Figure Description
[0021] Figure 1 The image shows a scanning electron microscope (SEM) image of the MgGa2O4 epitaxial thin film prepared in Example 1.
[0022] Figure 2 The image shows the energy-dispersive X-ray spectroscopy (EDXS) spectrum of the MgGa2O4 epitaxial thin film prepared in Example 1. The horizontal axis represents X-ray energy (keV), and the vertical axis represents X-ray counts (Counts).
[0023] Figure 3 The image shows the energy-dispersive X-ray spectrum (EDXS) of the thin film prepared in Comparative Example 1. The horizontal axis represents X-ray energy (keV), and the vertical axis represents X-ray counts (Counts).
[0024] Figure 4 The image shows the energy-dispersive X-ray spectrum (EDXS) of the thin film prepared in Comparative Example 2. The horizontal axis represents X-ray energy (keV), and the vertical axis represents X-ray counts.
[0025] Figure 5 The image shows the energy-dispersive X-ray spectra (EDXS) of the thin film prepared in Comparative Example 3. The horizontal axis represents X-ray energy (keV), and the vertical axis represents X-ray counts.
[0026] Figure 6 This is a schematic diagram of the vertical hot-wall atomized chemical vapor deposition equipment used in this invention.
[0027] The annotations in the attached figures are explained as follows: 1. Ultrasonic atomizing plate; 2. Argon gas inlet of atomizing can; 3. Oxygen gas inlet of atomizing can; 4. Atomizing can; 5. Gas outlet of atomizing can; 6. Gas inlet at the bottom of the reaction chamber; 7. Gas outlet at the bottom of the reaction chamber; 8. Funnel; 9. Substrate; 10. Tray; 11. Reaction chamber; 12. Resistance wire; 13. Argon gas pipeline outlet; 14. Oxygen gas pipeline outlet. Detailed Implementation
[0028] To make the above-mentioned objectives, features, and advantages of the embodiments of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0029] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.
[0030] The technical solution of the present invention will be further illustrated below with specific examples.
[0031] Figure 6 This is a schematic diagram of the vertical hot-wall atomized chemical vapor deposition equipment used in this invention, mainly including: an atomizing tank 4 and a reaction chamber 11. The atomizing tank 4 is used to store the prepared MgGa2O4 precursor solution. The top of the atomizing tank 4 is provided with an atomizing tank outlet 5, and the atomizing tank 4 is provided with an atomizing tank argon inlet 2. Argon gas enters the atomizing tank 4 through the atomizing tank argon inlet 2 via the argon gas outlet 13 of the argon gas pipeline, and the argon gas flow rate is 4000 mL / min. The atomizing tank 4 is provided with an atomizing tank oxygen inlet 3, and oxygen enters the atomizing tank 4 through the atomizing tank oxygen inlet 3 via the oxygen outlet 14 of the oxygen pipeline. In this embodiment of the invention, only argon gas is used as the carrier gas, so the inlet valve is kept closed. This design allows the equipment to have the expansion capability of introducing other gases.
[0032] The bottom of the atomizing tank 4 is provided with an ultrasonic atomizing plate 1 for atomizing the MgGa2O4 precursor solution. The frequency of the ultrasonic atomizing plate 1 is 2.4MHz.
[0033] The outer wall of the reaction chamber 11 is wrapped with a resistance wire 12. The temperature of the resistance wire 12 after heating is 550°C. A pipe is provided at the bottom of the reaction chamber 11. The part of the pipe outside the reaction chamber 11 is the bottom air inlet 6 of the reaction chamber, and the part of the pipe inside the reaction chamber 11 is the bottom air outlet 7 of the reaction chamber. The bottom air inlet 6 of the reaction chamber is connected to the air outlet 5 of the atomizing can. The interior of the reaction chamber 11 is provided with a funnel 8, a substrate 9, and a tray 10 from top to bottom. The funnel 8 is vertically arranged in the reaction chamber 11, and its inlet is connected to the gas outlet 7 at the bottom of the reaction chamber. The funnel 8 has a flared outlet located below the substrate 9. The substrate 9 is placed horizontally in the reaction chamber 11, and the substrate 9 is detachably connected to the tray 10 (the detachable connection can be a snap-fit or a plug-in connection). The top of the tray 10 is connected to the top of the reaction chamber 11 via a liftable support rod. The distance between the funnel 8 and the substrate 9 is 10 mm. The top of the reaction chamber 11 is provided with an exhaust port that communicates with an exhaust device.
[0034] Before use, the substrate 9 is ultrasonically cleaned in acetone, ethanol and deionized water in sequence, and then the surface of the substrate 9 is purged with nitrogen to obtain the cleaned substrate 9; the cleaned substrate 9 is installed on the tray 10; the distance between the substrate 9 and the funnel 8 is adjusted, the oxygen pipeline outlet 14 is connected to the oxygen inlet 3 of the atomizing tank, and the argon pipeline outlet 13 is connected to the argon inlet 2 of the atomizing tank.
[0035] Example 1 A method for preparing MgGa2O4 epitaxial thin films includes the following steps: The sapphire substrate was ultrasonically cleaned in acetone for 5 minutes to remove organic contaminants, then ultrasonically cleaned in ethanol for 5 minutes to remove acetone, and finally ultrasonically cleaned in deionized water for 5 minutes to remove ethanol. The surface of the cleaned sapphire substrate was then purged with nitrogen gas to dry it. The cleaned sapphire substrate was then mounted on a tray in the reaction chamber.
[0036] Weigh 1.83525g of gallium acetylacetonate and place it in a beaker. Add 100ml of deionized water and 1.5mL of hydrochloric acid (to promote the dissolution of gallium acetylacetonate) to the beaker. Place a magnetic stir bar in the beaker and place it on a magnetic stirrer. Stir until the gallium acetylacetonate solution is clear and transparent with no solid drug residue, to obtain 100ml of gallium acetylacetonate solution with a concentration of 0.05mol / L.
[0037] Weigh 5.36125g of magnesium acetate tetrahydrate and place it into 100ml of a 0.05mol / L gallium acetylacetonate solution. Place a magnetic stir bar in the beaker and put it on a magnetic stirrer. Stir until the MgGa2O4 precursor solution (i.e., a mixed solution of magnesium acetate tetrahydrate and gallium acetylacetonate) becomes clear and transparent, and 100ml of a 0.3mol / L MgGa2O4 precursor solution is obtained.
[0038] Pour 100ml of the prepared MgGa2O4 precursor solution into the atomizing tank. Connect the argon gas outlet to the argon gas inlet of the atomizing tank, connect the oxygen gas outlet to the oxygen inlet of the atomizing tank, connect the atomizing tank outlet to the bottom inlet of the reaction chamber, and connect the funnel to the bottom outlet of the reaction chamber. Adjust the distance between the substrate on the tray and the funnel to 10mm.
[0039] The temperature of the reaction chamber was raised to 550℃ and held for 15 minutes. Aeration was then initiated by introducing argon carrier gas into the reaction chamber for 15 minutes, ensuring the chamber was filled with argon. Excess air was then expelled from the reaction chamber using an exhaust device. An ultrasonic atomizer was used to convert the MgGa2O4 precursor solution in the atomization tank into atomized droplets, which were transported to the reaction chamber by the carrier gas. A chemical reaction was then carried out on the substrate surface at 550℃ for 60 minutes to prepare a MgGa2O4 epitaxial thin film. Atomization, aeration, and heating were sequentially stopped. After the atomized chemical vapor deposition equipment cooled to room temperature, the substrate was removed, yielding the MgGa2O4 epitaxial thin film.
[0040] Reaction mechanism (chemical reaction equation): Magnesium acetate tetrahydrate decomposes at high temperature to form magnesium oxide (MgO), releasing carbon dioxide and water: Mg(CH3COO)2⋅4H2O→MgO+4CO2↑+6H2O↑; Gallium acetylacetonate decomposes to form gallium oxide (Ga2O3), while simultaneously releasing acetylacetonate (C5H8O2). 2Ga(C5H7O2)3+3H2O→Ga2O3+6C5H8O2; The generated MgO and Ga2O3 further react at high temperature to form a MgGa2O4 thin film: MgO + Ga2O3 → MgGa2O 4。
[0041] Comparative Example 1 This comparative example provides a method for preparing MgGa2O4 epitaxial thin films that is basically the same as that in Example 1, except that 100 ml of a 0.1 mol / L MgGa2O4 precursor solution is prepared. The preparation steps are as follows: Weigh 1.07225 g of magnesium acetate tetrahydrate and add it to 100 mL of 0.05 mol / L gallium acetylacetonate solution. Place a magnetic stir bar in the beaker and put it on a magnetic stirrer. Stir until the MgGa2O4 precursor solution (i.e., the mixed solution of magnesium acetate tetrahydrate and gallium acetylacetonate) becomes clear and transparent.
[0042] Comparative Example 2 This comparative example provides a method for preparing a MgGa2O4 epitaxial thin film that is basically the same as in Example 1, except that 100 ml of a 0.15 mol / L MgGa2O4 precursor solution is prepared. The preparation steps are as follows:
[0043] Weigh 2.1445 g of magnesium acetate tetrahydrate and place it in 100 ml of a prepared gallium acetylacetonate solution with a concentration of 0.05 mol / L. Place a magnetic stir bar in the solution and place the beaker on a magnetic stirrer. Stir until the MgGa2O4 precursor solution (i.e., a mixed solution of magnesium acetate tetrahydrate and gallium acetylacetonate) becomes clear and transparent.
[0044] Comparative Example 3 This comparative example provides a MgGa2O4 epitaxial thin film and its preparation method. The preparation method is basically the same as that in Example 1, except that the reaction chamber is heated to 500°C and kept at that temperature for 15 minutes at the beginning of heating.
[0045] When starting the ventilation, introduce argon gas at a flow rate of 2000 mL / min into the reaction chamber for 15 minutes to fill the reaction chamber with argon gas and remove excess air.
[0046] Experimental Analysis (1) SEM Figure 1 The image shows a surface scanning electron microscope (SEM) image of the MgGa2O4 epitaxial thin film prepared in Example 1. Figure 1 It can be seen that the MgGa2O4 epitaxial film prepared in Example 1 has protruding MgGa2O4 grains on its surface.
[0047] (2) Energy dispersive X-ray spectroscopy Figure 2 The image shows the energy-dispersive X-ray spectrum of the MgGa2O4 epitaxial thin film prepared in Example 1. according to Figure 2 It is known that the MgGa2O4 epitaxial film prepared in Example 1 contains Al, Ga, Mg, C, and O elements. The Al element originates from the sapphire substrate, while the Ga, Mg, and O elements originate from the MgGa2O4 film itself, and the C element originates from C impurities introduced from the precursor. Furthermore, the Mg:Ga ratio is approximately 1:2, indicating that the MgGa2O4 epitaxial film prepared in Example 1 conforms to the standard stoichiometry. According to existing research (Effects of Mg Component Ratio on Photodetection Performance of MgGa2O4 Solar-Blind Ultraviolet Photodetectors), devices prepared from MgGa2O4 epitaxial films conforming to the standard stoichiometry exhibit optimal photoelectric performance.
[0048] Figure 3 The energy-dispersive X-ray spectrum of the MgGa2O4 epitaxial thin film prepared in Comparative Example 1 is shown below. Figure 3It can be seen that the epitaxial film prepared in Comparative Example 1 contains Al, Ga, C, O and Cl elements, but no Mg element, indicating that the amount of magnesium acetate tetrahydrate added is too small to prepare MgGa2O4 epitaxial film.
[0049] Figure 4 The energy-dispersive X-ray spectrum of the MgGa2O4 epitaxial film prepared in Comparative Example 2 is shown below. Figure 4 It can be seen that the epitaxial film prepared in Comparative Example 2 contains Al, Ga, C, O and Cl elements, but no Mg element, indicating that the amount of magnesium acetate tetrahydrate added is too small to prepare MgGa2O4 epitaxial film.
[0050] Figure 5 The energy-dispersive X-ray spectrum of the MgGa2O4 epitaxial thin film prepared in Comparative Example 3 is shown below. Figure 5 It can be seen that the epitaxial film prepared in Comparative Example 3 contains Al, Ga, C, O and Cl elements, but does not contain Mg element. This indicates that the heating temperature in the atomized chemical vapor deposition method is too low to prepare MgGa2O4 epitaxial film.
[0051] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. A method for preparing MgGa2O4 epitaxial thin films, characterized in that, Includes the following steps: After cleaning, the substrate is placed inside the reaction chamber; Prepare gallium acetylacetone solution; Magnesium acetate tetrahydrate was added to a gallium acetylacetonate solution to prepare a 0.3 mol / L MgGa₂O₄ precursor solution, wherein the MgGa₂O₄ precursor solution contained Mg 2+ / Ga 3+ The molar ratio is 5:1; The prepared MgGa2O4 precursor solution was converted into atomized droplets by atomized chemical vapor deposition and transported to the reaction chamber by a carrier gas. The MgGa2O4 epitaxial film was prepared by chemical reaction on the substrate surface at 550°C.
2. The method for preparing MgGa2O4 epitaxial thin films according to claim 1, characterized in that, The preparation steps of the gallium acetylacetonate solution are as follows: deionized water and hydrochloric acid are added to gallium acetylacetonate in sequence, and the solution is stirred until the gallium acetylacetonate dissolves and the solution becomes clear and transparent, thus obtaining the gallium acetylacetonate solution.
3. The method for preparing MgGa2O4 epitaxial thin films according to claim 1, characterized in that, The concentration of the gallium acetylacetonate solution is 0.05 mol / L.
4. The method for preparing MgGa2O4 epitaxial thin films according to claim 1, characterized in that, The carrier gas is argon, and the carrier gas flow rate is 4000 mL / min.
5. The method for preparing MgGa2O4 epitaxial thin films according to claim 1, characterized in that, The MgGa2O4 precursor solution was atomized using ultrasonic atomization at a frequency of 2.4 MHz.
6. The method for preparing MgGa2O4 epitaxial thin films according to claim 1, characterized in that, The substrate is sapphire.
7. The method for preparing MgGa2O4 epitaxial thin films according to claim 1, characterized in that, The substrate was sequentially subjected to ultrasonic cleaning in acetone, ethanol, and deionized water, and then dried by purging with nitrogen.
8. The method for preparing MgGa2O4 epitaxial thin films according to claim 1, characterized in that, The reaction time is 60 minutes.
9. The MgGa2O4 epitaxial thin film prepared by the method according to any one of claims 1 to 8.