Zinc gallate film prepared by two-step method and preparation method and application thereof

Abstract

The present invention discloses a two-step method for preparing a zinc gallate film, a preparation method and an application, and belongs to the technical field of semiconductor materials. The present invention provides a two-step method for preparing a zinc gallate film, comprising the following steps: pre-treating a C-surface sapphire substrate, removing surface impurities and moisture, and obtaining a pre-treated sapphire substrate; mixing a gallium acetylacetonate solution and a zinc acetylacetonate solution, adding hydrochloric acid, stirring until completely dissolved, and standing to obtain a supernatant; under normal pressure conditions, using an inert gas as a carrier gas, ultrasonically atomizing the supernatant and then transporting it to the surface of the pre-treated sapphire substrate, depositing at 500°C to 550°C to form a nucleation layer, and then heating to 600°C to 650°C to deposit an epitaxial film to obtain a single crystal spinel zinc gallate film. The present invention prepares a higher quality zinc gallate film through a two-step method.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor materials, and more specifically to a zinc gallate film prepared by a two-step method, a preparation method and an application thereof. Background Art

[0002] In the field of semiconductor material science, spinel oxides have attracted much attention due to their unique electronic structure and physical properties. In particular, zinc gallate, as a wide bandgap semiconductor material, has great application potential in the fields of new generation electronic devices, solar-blind ultraviolet detectors, photocatalysts, etc. due to its high electron mobility, excellent fluorescence effect, significant photocatalytic properties, good thermal stability and breakdown voltage.

[0003] However, traditional methods for preparing zinc gallate films, such as pulsed laser deposition, radio frequency magnetron sputtering, metal organic vapor chemical deposition, etc., usually need to be carried out in a high vacuum environment, which not only limits the growth rate, but also has high equipment costs and complex processes, making it difficult to achieve large-scale production. In addition, these methods make it difficult to control the atomic ratio of the film, so that the prepared zinc gallate films are mostly polycrystalline structures with poor crystal quality, which is difficult to meet the strict requirements of high-performance electronic devices for materials. Although the researchers used ultrasonic-assisted mist chemical vapor deposition to prepare zinc gallate films, the quality of the prepared zinc gallate films was relatively poor. Summary of the invention

[0004] In view of the above problems, the present invention provides a zinc gallate film prepared by a two-step method, a preparation method and an application thereof, and a zinc gallate film of higher quality is prepared by the two-step method.

[0005] The first object of the present invention is to provide a two-step method for preparing a zinc gallate thin film, comprising the following steps:

[0006] The C-surface sapphire substrate is pretreated to remove surface impurities and moisture to obtain a pretreated sapphire substrate.

[0007] After the gallium acetylacetonate solution and the zinc acetylacetonate solution are mixed, hydrochloric acid is added, stirred until completely dissolved, and allowed to stand to obtain a supernatant.

[0008] Under normal pressure, with inert gas as carrier gas, the supernatant is ultrasonically atomized and then transported to the surface of a pretreated sapphire substrate, kept at 500°C-550°C to form a nucleation layer, and then heated to 600°C-650°C to form an epitaxial film, thereby obtaining a single crystal spinel zinc gallate film.

[0009] It should be noted that the method for pre-treating the C-surface sapphire substrate is:

[0010] s101, surface cleaning

[0011] A C-plane sapphire substrate with a size of 10*15 cm was placed in an ultra-clean workbench to reduce contamination from dust and microorganisms in the air.

[0012] s102, chemical cleaning

[0013] Perform a preliminary cleaning of the substrate using analytical grade isopropanol with a purity greater than or equal to 99.5%. Completely immerse the substrate in the isopropanol and gently scrub the substrate surface with a soft brush to remove loose particles and organic contaminants. Then, remove the substrate and place it in a clean tray.

[0014] Next, the substrate is immersed in analytical pure anhydrous ethanol with a purity greater than or equal to 99.7% for secondary cleaning, and the surface of the substrate is gently scrubbed with a soft brush to further remove residual organic impurities. After cleaning, the substrate is taken out and placed in a new clean tray.

[0015] Finally, rinse the substrate thoroughly with deionized water to remove all chemical residues. Rinse with deionized water at least three times, replacing the water after each rinse.

[0016] s103, Drying treatment

[0017] Place the chemically cleaned substrate in a clean tray and dry it with nitrogen gas greater than or equal to 99.999%. The nozzle of the nitrogen gun is about 10 cm away from the substrate surface, and the substrate surface is evenly blown at a moderate pressure and speed until the substrate is completely dry without any water marks or water droplets remaining.

[0018] s104, ultraviolet disinfection

[0019] Place the dried substrate in a UV disinfection box and irradiate with UV light for at least 30 minutes to kill microorganisms that may remain on the surface of the substrate.

[0020] s105, storage and transportation

[0021] The pre-treated substrate should be immediately placed in a pre-sterilized sealed container to prevent re-contamination. Before transporting to the deposition room, ensure that the entire operation process is carried out in a dust-free environment to avoid new contamination of the substrate.

[0022] Through the above-mentioned pretreatment steps, the present invention ensures that the surface of the C-plane sapphire substrate reaches an extremely high cleanliness, providing ideal substrate conditions for subsequent thin film growth.

[0023] In a preferred embodiment of the present invention, the deposition time for forming the nucleation layer is 0.5 h.

[0024] In a preferred embodiment of the present invention, the deposition time for forming the epitaxial film is 1 hour.

[0025] In a preferred embodiment of the present invention, the molar ratio of gallium in the gallium acetylacetonate solution to zinc in the zinc acetylacetonate solution is 1.

[0026] The purity of gallium acetylacetonate used in the present invention is 99.99%, and the purity of zinc acetylacetonate is 99.99%.

[0027] In a preferred embodiment of the present invention, the frequency of the ultrasonic atomization treatment is 2.4 MHz.

[0028] In a preferred embodiment of the present invention, the flow rate of the inert gas is 5 L / min.

[0029] In a preferred embodiment of the present invention, the ultrasonic atomization treatment is performed using an ultrasonic atomizer; the distance between the pre-treated sapphire substrate and the reaction source nozzle of the ultrasonic atomizer is 10 mm.

[0030] In a preferred embodiment of the present invention, the stirring time is 6 hours.

[0031] The second object of the present invention is to provide a zinc gallate film prepared by the above preparation method.

[0032] The third object of the present invention is to provide application of the zinc gallate film in the preparation of optical devices.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. In the preparation of the present invention, the first step is to epitaxially grow a zinc gallate nucleation layer at 500°C to 550°C to relieve the mismatch stress between the substrate and the epitaxial film and relax the lattice strain, and then epitaxially grow a zinc gallate film at 600°C to 650°C on the nucleation layer to obtain a high-quality single crystal film. The present invention firstly epitaxially grows a nucleation layer at a low temperature to relax the lattice strain, relieves the lattice mismatch between the film and the substrate, and thus obtains a higher quality single crystal film.

[0035] 2. Reduced preparation costs and ease of operation: The chemical vapor deposition method used in the present invention does not require expensive vacuum equipment, thereby significantly reducing equipment costs and operating costs. In addition, by simplifying the process and using commercially available raw materials, such as high-purity gallium acetylacetonate and zinc acetylacetonate, the entire preparation process is more economical and efficient. At the same time, the operating steps of the method are clear and easy to control, which is convenient for technicians to quickly master and implement, and improves the flexibility and scalability of production. The present invention can significantly increase the growth rate of zinc gallate films to 1.5μm / h, which is much higher than traditional methods.

[0036] 3. The present invention achieves precise control of the crystal orientation of the film by precisely controlling the zinc-gallium molar ratio to 1:1 and the substrate pretreatment step, ensuring that the grown zinc gallate film has a (111) plane single crystal structure. This crystal-oriented film has better performance in the fields of optoelectronic devices and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the structure of the upper connecting rod device and the quartz plate designed for the present invention, wherein (a) is a schematic diagram of the structure of the upper connecting rod device, and (b) is a schematic diagram of the structure of the quartz plate.

[0038] Figure 2 This is the XRD diagram of the zinc gallate film prepared in Comparative Example 2 of the present invention.

[0039] Figure 3 This is the XRD pattern of the zinc gallate film prepared in Example 1 of the present invention.

[0040] Figure 4 for Figure 2 The enlarged view of the part and Figure 3 Comparison of the local enlarged images in the figure.

[0041] Figure 5 This is a SEM image of the zinc gallate film prepared in Example 1 of the present invention.

[0042] Figure 6 This is the XPS graph of the zinc gallate film prepared in Example 1 of the present invention.

[0043] Figure 7 This is the XRD diagram of the zinc gallate film prepared in Comparative Example 1 of the present invention.

[0044] Figure 8 This is a schematic diagram of preparing a photodetector with an interdigital structure according to the present invention.

[0045] Fig. 9 This is a current-voltage diagram of the zinc gallate film prepared in Example 1 of the present invention.

[0046] Fig.10 This is a current-time diagram of the zinc gallate film prepared in Example 1 of the present invention.

[0047] Reference numerals: 1 - upper connecting rod; 2 - quartz plate; 3 - zirconia nut. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Gallium acetylacetonate is the raw material for preparing gallium oxide in the process, and zinc acetylacetonate is the raw material for preparing zinc oxide. Therefore, when the gallium content in the solution is too high, the film will produce gallium oxide and zinc gallate. Similarly, when the zinc content is too high, the film will produce zinc oxide. Therefore, the content of the two elements is strictly controlled. Before use, in order to ensure that the molar ratio of zinc to gallium is exactly 1, the concentration of zinc and gallium in the solution can be detected by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy.

[0050] The chemical formula of zinc gallate is ZnGa2O4, in which the gallium element is twice the zinc element. The solution preparation follows this principle to prepare pure zinc gallate film. However, it is found in experiments that when the molar ratio of Zn to Ga is 1:2, the film produces gallium oxide, causing the zinc gallate film to have an impurity phase. Therefore, the present invention increases the zinc content so that a pure zinc gallate film is produced when Zn:Ga=1:1. This is because the zinc element is easy to evaporate at high temperature and is not easy to participate in the film reaction process, so its content is relatively larger.

[0051] During the preparation, the present invention selects a low-cost sapphire substrate for preparation, but the sapphire substrate is a corundum structure, and the lattice mismatch with the spinel structure zinc gallate film is large, about 6%, and it is difficult to epitaxially grow a high-quality single crystal film. Therefore, the present invention aims at this problem and proposes a method for single crystal spinel oxide film. By using chemical vapor deposition technology, the substrate pretreatment, precursor solution configuration and deposition process parameters are optimized at low temperature and normal pressure to achieve rapid growth of (111) surface single crystal structure zinc gallate film on the sapphire substrate. The film material with a single crystal structure is three-dimensionally ordered and has a higher crystallinity. Compared with the traditional method, the present invention not only significantly reduces the preparation cost and improves the growth rate, but also uses low temperature to alleviate the evaporation of zinc element, accurately adjusts the zinc-gallium molar ratio, and prepares high-quality single crystal film, providing an efficient and economical material preparation scheme for applications in optoelectronic devices and other fields.

[0052] During the preparation, in order to ensure the stability of the substrate and the uniformity of the film during the film growth process, thereby improving the quality and efficiency of the film growth, the present invention selects a patterned quartz sheet with a size matching the C-plane sapphire substrate, and the size is 10cm*15cm, so as to ensure that the substrate can be completely placed on the quartz sheet.

[0053] like Figure 1As shown, according to the size and shape of the substrate, the patterned quartz wafer is designed and processed so that its surface has hollow parts that match the shape of the substrate. These hollow parts help to form a uniform interlayer space between the substrate and the quartz wafer, thereby ensuring the stability of the substrate during the growth process. The pre-treated C-plane sapphire substrate is placed on the hollow parts of the patterned quartz wafer. Ensure that the contact between the substrate and the quartz wafer is uniform, without obvious warping or tilting. Figure 1 As shown in (a) in the figure, prepare a mechanical device, usually an upper connecting rod with a fixing clamp, to fix the substrate and maintain its position during the growth process. Place the patterned quartz plate together with the substrate in the fixing clamp of the upper connecting rod. Use at least four sets of zirconia nuts to fix the patterned quartz plate on the upper connecting rod to ensure that the substrate does not move during the growth process. The height of the upper connecting rod is adjusted by the mechanical device so that the distance between the substrate and the reaction source is accurately controlled to 10mm. This distance is critical to the uniformity and quality of film growth. After fixing the substrate, carefully check to ensure that the contact between the substrate and the quartz plate is tight and the substrate is fixed stably on the upper connecting rod. The stability of the substrate can be tested by gently shaking the upper connecting rod. If necessary, fine-tune the height of the upper connecting rod or the tightness of the zirconia nuts to ensure the accuracy of the substrate position. Before placing the fixed substrate and upper connecting rod combination into the growth chamber, perform a final visual inspection and confirmation to ensure that the position and fixation of the substrate meet the growth requirements.

[0054] Under normal pressure, with inert gas as carrier gas, the supernatant layer is ultrasonically atomized and then transported to the surface of a pretreated sapphire substrate. It is first kept at 500°C-550°C to form a nucleation layer, and then heated to 600°C-650°C to form an epitaxial film to obtain a single crystal spinel zinc gallate film.

[0055] The following are the specific preparation steps:

[0056] s401, Chemical Vapor Deposition System Preparation: Check all components of the Chemical Vapor Deposition system, including the reaction chamber, ultrasonic atomizer, gas delivery system, temperature control system, etc., to ensure that they are in good working condition.

[0057] s402. Loading of precursor solution: Load the prepared supernatant into the ultrasonic atomization tank, ensuring that the amount of solution is sufficient to support the entire growth process.

[0058] s403. Ultrasonic atomization setting: The frequency of the ultrasonic atomizer is set to 2.4 MHz to ensure that the supernatant liquid can be effectively atomized into fine droplets to facilitate thermal decomposition and reaction during the chemical vapor deposition process.

[0059] s404, Carrier gas flow adjustment: Set the flow rate of inert gas argon to 5L / min and accurately control it through a mass flow controller to ensure stable gas delivery.

[0060] s405, epitaxial nucleation layer: Use a temperature control system to heat the substrate to 500℃~550℃ and maintain this temperature range throughout the growth process. This temperature range is optimized to promote thermal decomposition of the precursor and growth of the film. After reaching the set substrate temperature, start the ultrasonic atomizer to begin atomizing the precursor solution. At the same time, maintain the argon flow rate to deliver the atomized precursor droplets to the substrate surface. The growth time is precisely controlled to 30 minutes for epitaxial nucleation layer. This is achieved by the built-in timer of the chemical vapor deposition system. Precise control of the growth time is critical to obtaining a film of the desired thickness and quality.

[0061] s406, epitaxial zinc gallate film: Use a temperature control system to heat the substrate to 600℃~650℃ and maintain this temperature range throughout the growth process. This temperature range can promote the thermal decomposition of the precursor and the growth of the film. After reaching the set substrate temperature, start the ultrasonic atomizer to begin atomizing the precursor solution. At the same time, maintain the argon flow rate to deliver the atomized precursor droplets to the substrate surface. The growth time is precisely controlled to be 1h, and the epitaxial nucleation layer is achieved through the built-in timer of the chemical vapor deposition system. Precise control of the growth time is crucial to obtaining a film of the desired thickness and quality.

[0062] s407, Growth Environment Monitoring: Throughout the growth process, the pressure, temperature and gas flow within the chemical vapor deposition system are continuously monitored to ensure that they remain within the predetermined parameters.

[0063] s408. Post-growth treatment: Once the predetermined growth time is reached, turn off the ultrasonic atomizer and gas flow controller and let the system cool naturally to room temperature. During the cooling process, avoid direct contact with the substrate to prevent thermal shock.

[0064] s409. Removal and inspection of thin films: After the system has completely cooled, carefully remove the substrate and inspect the morphology and uniformity of the film using an optical microscope and / or other analytical tools.

[0065] s410, Post-treatment: If necessary, the grown film is post-treated, such as annealing, polishing or other surface treatments, to further improve the quality and performance of the film.

[0066] Through the above detailed chemical vapor deposition process steps, the present invention can accurately control various key parameters of film growth, thereby growing high-quality zinc gallate films.

[0067] In order to ensure uniformity and accuracy during the film growth process and better place the 10cm×15cm C-plane sapphire substrate, the present invention provides a quartz sheet, such as Figure 1 As shown in (b), the quartz plate is provided with multiple hollow parts, and the multiple hollow parts match the shape of the substrate to ensure good contact between the substrate and the quartz plate. During the experiment, a circular quartz plate that matches the upper connecting rod is selected, and a hollow design is made on the quartz plate according to the experimental and substrate requirements to facilitate the placement of small substrates. Four sets of zirconia nuts are used to fix the quartz plate on the upper connecting rod in the chemical vapor deposition reaction chamber to form a uniform gap. The pretreated sapphire substrate is accurately placed on the hollow part of the quartz plate, and the zirconia nuts are tightened to fix the substrate. By manually adjusting the height of the upper connecting rod, the distance between the substrate and the reaction source is accurately controlled at 10 mm to ensure the uniformity of film growth.

[0068] Example 1

[0069] s1. Substrate pretreatment

[0070] In the clean bench, a 10cm×15cm C-side sapphire substrate was pretreated. First, it was rinsed with 500mL of analytical pure isopropanol, and the substrate surface was gently brushed with a soft brush for 2 minutes to remove organic pollutants. Then, this process was repeated with 500mL of anhydrous ethanol to further remove residual organic matter. Finally, it was rinsed with 1000mL of deionized water for 2 minutes to remove inorganic salt impurities. After each chemical cleaning, nitrogen with a purity of more than 99.999% was used to purge at a distance of 5cm from the substrate until the surface was completely dry to obtain a pretreated sapphire substrate.

[0071] s2. Precursor solution preparation

[0072] Use an electronic balance with an accuracy of 0.01 grams to accurately weigh 1.85 grams of 99.99% pure gallium acetylacetonate and dissolve it in 50 mL of deionized water to obtain a gallium acetylacetonate solution, dissolve 1.3 grams of 99.99% pure zinc acetylacetonate in 50 mL of deionized water to obtain a zinc acetylacetonate solution, and then mix the zinc acetylacetonate solution and the gallium acetylacetonate solution in a 250 mL round-bottom flask to obtain a precursor solution. The molar ratio of Ga to Zn in the precursor solution is 1:1, and 1.52 mL of concentrated hydrochloric acid with a mass concentration of 36% is added to promote the dissolution of gallium acetylacetonate. Stir at room temperature with a magnetic stirrer for 6 hours to ensure that the solution is fully mixed and dissolved. After stirring, place the flask at room temperature for at least 2 hours to promote the sedimentation of insoluble impurities. Use a clean pipette to absorb the supernatant and transfer it to a pre-sterilized and dried container for use.

[0073] s3, substrate fixation

[0074] Prepare Figure 1 The patterned quartz wafer shown has dimensions that match the sapphire substrate and has a hollowed-out portion in the center that matches the substrate shape. The patterned quartz wafer is fixed to the upper connecting rod in the chemical vapor deposition reaction chamber using four sets of zirconia nuts to form a uniform gap. The pre-treated sapphire substrate is precisely placed on the hollowed-out portion of the patterned quartz wafer and the zirconia nuts are tightened to secure the substrate. By manually adjusting the height of the upper connecting rod, the distance between the substrate and the reaction source is precisely controlled to 10 mm to ensure uniform film growth.

[0075] s4. Chemical vapor deposition growth process

[0076] Add the prepared supernatant to the ultrasonic atomization tank, and set the temperature of the chemical vapor deposition reaction chamber to 550°C. The flow rate of argon is precisely controlled by a mass flow controller and set to 5L / min. Open the carrier gas line and keep ventilating for at least 1 hour to ensure that the argon fills the entire reaction chamber. Start the ultrasonic atomizer, set the frequency to 2.4MHz, and start atomizing the precursor solution. By controlling the atomization knob, accurately adjust the atomization amount to ensure uniform evaporation and delivery of the solution. Atomize for 30 minutes to epitaxially form the nucleation layer, turn off the atomization and keep ventilating for 30 minutes to promote the uniform deposition and reaction of the nucleation layer on the substrate surface, and then continue to heat up to 650°C, and epitaxially grow a zinc gallate film with a thickness of about 1.5μm for 1 hour.

[0077] Example 2

[0078] s1. Substrate pretreatment

[0079] In the clean bench, a 10cm×15cm C-side sapphire substrate was thoroughly pretreated. First, it was rinsed with 500mL of analytical pure isopropanol, and the substrate surface was gently brushed with a soft brush for 2 minutes to remove organic pollutants. Then, 500mL of anhydrous ethanol was used to repeat the cleaning process for 2 minutes to further remove residual organic matter. Finally, 1000mL of deionized water was used to rinse for 2 minutes to remove inorganic salt impurities. After each chemical cleaning, nitrogen with a purity of more than 99.999% was used to purge at a distance of 5cm from the substrate until the surface was completely dry to obtain a pretreated sapphire substrate.

[0080] s2. Precursor solution preparation

[0081] Use an electronic balance with an accuracy of 0.01 grams to accurately weigh 1.85 grams of 99.99% pure gallium acetylacetonate and dissolve it in 50 mL of deionized water to obtain a gallium acetylacetonate solution, and dissolve 1.3 grams of 99.99% pure zinc acetylacetonate in 50 mL of deionized water to obtain a zinc acetylacetonate solution. Then mix the zinc acetylacetonate solution and the gallium acetylacetonate solution in a 250 mL round-bottom flask to obtain a precursor solution. The molar ratio of Ga to Zn in the precursor solution is 1:1, and 1.52 mL of concentrated hydrochloric acid with a mass concentration of 36% is added to promote the dissolution of gallium acetylacetonate. Stir with a magnetic stirrer at room temperature for 6 hours to ensure that the solution is fully mixed and dissolved. After stirring, place the flask at room temperature for at least 2 hours to promote the sedimentation of insoluble impurities. Use a clean pipette to absorb the supernatant and transfer it to a pre-sterilized and dried container for use.

[0082] s3, substrate fixation

[0083] Prepare a custom patterned quartz sheet with dimensions matching the sapphire substrate and a hollowed-out portion in the center that matches the substrate shape. Use four sets of zirconia nuts to fix the patterned quartz sheet to the upper connecting rod in the chemical vapor deposition reaction chamber to form a uniform gap. Place the pre-treated sapphire substrate precisely on the hollowed-out portion of the patterned quartz sheet and tighten the zirconia nuts to fix the substrate. By manually adjusting the height of the upper connecting rod, ensure that the distance between the substrate and the reaction source is precisely controlled to 10 mm to ensure uniform film growth.

[0084] s4. Chemical vapor deposition growth process

[0085] Add the prepared supernatant to the ultrasonic atomization tank, and set the temperature of the chemical vapor deposition reaction chamber to 500°C. The flow rate of argon is precisely controlled by a mass flow controller and set to 5L / min. Open the carrier gas line and keep ventilating for at least 1h to ensure that the argon fills the entire reaction chamber. Start the ultrasonic atomizer, set the frequency to 2.4MHz, and start atomizing the precursor solution. By controlling the atomization knob, accurately adjust the atomization amount to ensure uniform evaporation and delivery of the solution. Atomize for 30 minutes to epitaxially form the nucleation layer, turn off the atomization and keep ventilating for 30 minutes to promote uniform deposition and reaction of the nucleation layer on the substrate surface, then continue to heat up to 600°C, and epitaxially grow a zinc gallate film with a thickness of about 1.2μm for 1h.

[0086] Comparative Example 1

[0087] s1. Substrate pretreatment

[0088] In the clean bench, the 10cm×15cm C-side sapphire substrate was first thoroughly rinsed with analytical grade isopropanol, and the surface was gently brushed with a clean soft brush for 2 minutes to remove organic pollutants. Subsequently, the substrate was cleaned twice with anhydrous ethanol in the same way to further remove residual organic matter, and the duration was also 2 minutes. Finally, it was rinsed with deionized water to remove any inorganic salt impurities, also for 2 minutes. After each chemical cleaning, the substrate was blown dry with nitrogen gas with a purity of more than 99.999% to ensure that the substrate surface was dry and free of water marks, and a pre-treated sapphire substrate was obtained.

[0089] s2. Precursor solution preparation

[0090] 1.85 g of 99.99% pure gallium acetylacetonate was accurately weighed and dissolved in 50 mL of deionized water to obtain a gallium acetylacetonate solution, 0.65 g of 99.99% pure zinc acetylacetonate was dissolved in 50 mL of deionized water to obtain a zinc acetylacetonate solution, and then the zinc acetylacetonate solution and the gallium acetylacetonate solution were mixed to obtain a precursor solution, in which the molar ratio of Ga to Zn in the precursor solution was 2:1, and 1.52 mL of concentrated hydrochloric acid with a mass concentration of 36% was added to promote the dissolution of gallium acetylacetonate. A magnetic stirrer was used to stir at room temperature for 6 hours to ensure that all powders were completely dissolved. After stirring, the solution was allowed to stand for at least 2 hours to allow insoluble impurities to settle. Afterwards, the supernatant was aspirated with a sterilized pipette and transferred to a sterilized and dried container for later use.

[0091] s3, substrate fixation

[0092] A custom patterned quartz wafer is used, whose size matches the sapphire substrate and has a hollow part that matches the shape of the substrate to ensure good contact between the substrate and the quartz wafer. Four sets of zirconia nuts are used to fix the patterned quartz wafer to the upper connecting rod in the chemical vapor deposition reaction chamber to form a uniform gap. The pre-treated sapphire substrate is precisely placed on the hollow part of the patterned quartz wafer, and the zirconia nuts are tightened to fix the substrate. By manually adjusting the height of the upper connecting rod, the distance between the substrate and the reaction source is precisely controlled to 10mm to ensure uniform film growth.

[0093] s4. Chemical vapor deposition growth process

[0094] Add the prepared supernatant to the ultrasonic atomization tank, and set the temperature of the chemical vapor deposition reaction chamber to 550°C. At the same time, the flow rate of argon is precisely controlled to 5L / min by the mass flow controller. Before starting atomization, keep the carrier gas line ventilated for at least 1h to ensure that the argon fills the entire reaction chamber. Subsequently, start the ultrasonic atomizer, set the frequency to 2.4MHz, and start atomizing the precursor solution. By controlling the atomization knob, accurately adjust the atomization amount to ensure uniform evaporation and delivery of the solution. Maintain the above conditions to atomize for 30min to epitaxially form the nucleation layer, turn off the atomization and keep ventilation for 30min to promote the uniform deposition and reaction of the nucleation layer on the substrate surface, and then continue to heat up to 650°C for 1h. Due to the excessive zinc content, zinc gallate and zinc oxide films grow simultaneously on the substrate surface.

[0095] Comparative Example 2

[0096] s1. Substrate pretreatment

[0097] In the clean bench, a 10cm×15cm C-side sapphire substrate was thoroughly pretreated. First, it was rinsed with 500mL of analytical pure isopropanol, and the substrate surface was gently brushed with a soft brush for 2 minutes to remove organic pollutants. Then, 500mL of anhydrous ethanol was used to repeat the cleaning process for 2 minutes to further remove residual organic matter. Finally, 1000mL of deionized water was used to rinse for 2 minutes to remove inorganic salt impurities. After each chemical cleaning, nitrogen with a purity of more than 99.999% was used to purge at a distance of 5cm from the substrate until the surface was completely dry to obtain a pretreated sapphire substrate.

[0098] s2. Precursor solution preparation

[0099] Use an electronic balance with an accuracy of 0.01 grams to accurately weigh 1.85 grams of 99.99% pure gallium acetylacetonate and dissolve it in 50 mL of deionized water to obtain a gallium acetylacetonate solution, and dissolve 1.3 grams of 99.99% pure zinc acetylacetonate in 50 mL of deionized water to obtain a zinc acetylacetonate solution. Then mix the zinc acetylacetonate solution and the gallium acetylacetonate solution in a 250 mL round-bottom flask to obtain a precursor solution. The molar ratio of Ga to Zn in the precursor solution is 1:1, and 1.52 mL of concentrated hydrochloric acid with a mass concentration of 36% is added to promote the dissolution of gallium acetylacetonate. Stir with a magnetic stirrer at room temperature for 6 hours to ensure that the solution is fully mixed and dissolved. After stirring, place the flask at room temperature for at least 2 hours to promote the sedimentation of insoluble impurities. Use a clean pipette to absorb the supernatant and transfer it to a pre-sterilized and dried container for use.

[0100] s3, substrate fixation

[0101] Prepare a custom patterned quartz sheet with dimensions matching the sapphire substrate and a hollowed-out portion in the center that matches the substrate shape. Use four sets of zirconia nuts to fix the patterned quartz sheet to the upper connecting rod in the chemical vapor deposition reaction chamber to form a uniform gap. Place the pre-treated sapphire substrate precisely on the hollowed-out portion of the patterned quartz sheet and tighten the zirconia nuts to fix the substrate. By manually adjusting the height of the upper connecting rod, ensure that the distance between the substrate and the reaction source is precisely controlled to 10 mm to ensure uniform film growth.

[0102] s4. Chemical vapor deposition growth process

[0103] Add the prepared supernatant to the ultrasonic atomization tank, and set the temperature of the chemical vapor deposition reaction chamber to 600°C. Use a mass flow controller to accurately control the flow rate of argon and set it to 5L / min. Open the carrier gas line and keep it ventilated for at least 1 hour to ensure that the argon fills the entire reaction chamber. Start the ultrasonic atomizer, set the frequency to 2.4MHz, and start atomizing the precursor solution. By controlling the atomization knob, accurately adjust the atomization amount to ensure uniform evaporation and delivery of the solution. Atomize the epitaxial nucleation layer for 1 hour, turn off the atomization and keep ventilation for 30 minutes to promote the uniform deposition of the nucleation layer on the substrate surface and the reaction growth of the zinc gallate film.

[0104] Figure 2 This is the XRD pattern of the film prepared in Comparative Example 2. Figure 3 This is the XRD pattern of the film prepared in Example 1. Figure 2 and Figure 3 It can be seen that in addition to the substrate peak, there are diffraction peaks at 18.5°, 37.7°, and 58.1°, corresponding to the (111) plane, (222) plane, and (333) plane of zinc gallate, respectively. This confirms that a single crystal zinc gallate film is obtained on a sapphire substrate with a large lattice mismatch. The peak value of the diffraction peak of the zinc gallate film is observed by the XRD diagram. Generally speaking, the stronger the peak value, the better the quality of the zinc gallate film. Figure 4 for Figure 2 The enlarged view of the part and Figure 3 The comparison of the local enlarged picture in Figure 4 It can be seen that the diffraction peak intensity of the zinc gallate film in Example 1 is greater, indicating that the zinc gallate film grown by the two-step method has better quality.

[0105] Figure 5 is a SEM image of the zinc gallate film prepared in Example 1. Figure 5 It can be seen that there is an obvious boundary between the substrate and the film and the film is uniform. At the same time, the thickness is 1.5μm, indicating that the growth rate is fast and can reach 1.5μm / h.

[0106] Figure 6 This is an XPS image of the zinc gallate film prepared in Example 1. Figure 6 It can be seen that the film contains C impurities, which is caused by C contamination in the external environment. The test results show that Ga / O=2.03, and a zinc gallate film with a near stoichiometric ratio is prepared.

[0107] Figure 7 The XRD pattern of the film prepared in Comparative Example 1 is shown in FIG. Figure 7 It can be seen that in addition to the substrate peak, there are diffraction peaks at 18.5°, 37.7°, 58.1° and 34.7°, 36.5°, corresponding to the (111) plane, (222) plane, (333) plane of zinc gallate and the (002) plane, (101) plane of zinc oxide, respectively. This confirms that when the zinc content is too high, zinc gallate and zinc oxide films grow simultaneously.

[0108] The zinc gallate film prepared by the present invention can be used to prepare a metal-semiconductor-metal photodetector, and the zinc gallate film prepared in Example 1 is used as an example for preparation. The preparation method is prepared with reference to "High-performance solar-blind photodetector based on Si-doped α-Ga2O3thin films grown by mist chemical vapor deposition" published by Ouyang Huijia in "JOURNAL OF ALLOYSAND COMPOUNDS" in 2024. The manufacturer of the lithography machine used in the present invention is Hughes Microtechnology Co., Ltd., and the instrument number is 1404308S. The ultraviolet light source of the lithography machine is 365nm.

[0109] The specific preparation method is:

[0110] The zinc gallate film was rinsed with ethanol and deionized water and dried at 110°C for 3 min to remove moisture.

[0111] Turn on the power supply and gas channel of the spin coater, place the sample and coat the photoresist by spin coating, the coating time is 30 seconds, take out the sample after the coating, and dry it at 110° C. for 3 minutes to obtain the coated sample.

[0112] Turn on the photolithography machine and wait for the mercury lamp to preheat for 20 minutes, place the mask, and suck the plate. Set the exposure time to 7s and perform photolithography. After the photolithography is completed, use the developer to dissolve the soluble area on the photoresist, leaving the circuit pattern on the surface of the zinc gallate film. The developer is a piranha solution and water in a volume ratio of 1:6. The piranha solution is a mixture of sulfuric acid with a concentration of 18.4 mol / L and 30% hydrogen peroxide in a volume ratio of 7:3. Develop for 30s and rinse with deionized water to obtain the photolithography sample.

[0113] The photolithography sample was sequentially evaporated with Ti and Au electrodes using an electron beam, with the thickness of Ti being 30 nm and the thickness of Au being 20 nm.

[0114] Figure 8 The schematic diagram of the photodetector with an interdigital structure is shown. The photodetector has 13 pairs of interdigital electrodes with a width of 100 μm, a length of 500 μm, and a finger spacing of 10 μm, so the effective illumination area of ​​the photodetector is calculated to be 1.25×10 -3 cm 2 .

[0115] Fig. 9 and Fig.10 The current-voltage diagram and current-time diagram of the metal-semiconductor-metal photodetector prepared using the zinc gallate film of Example 1. Fig. 9 and Fig.10 It can be seen that the device has a 3.83×10 2 The light-to-dark current ratio is high, and the detector response time is short and uniform, indicating that the device prepared by using the zinc gallate film of the present invention has high repeatability and good stability.

[0116] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0117] Obviously, those skilled in the art may 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 two-step method for preparing zinc gallate thin film, characterized in that: The following steps are involved: Pre-treating the C-surface sapphire substrate to remove surface impurities and moisture to obtain a pre-treated sapphire substrate; After mixing the gallium acetylacetonate solution and the zinc acetylacetonate solution, hydrochloric acid is added, stirred until completely dissolved, and allowed to stand to obtain a supernatant; Under normal pressure conditions, with inert gas as the carrier gas, the upper clear liquid is ultrasonically atomized and then transported to the surface of the pretreated sapphire substrate, deposited at 500°C to 550°C for 0.5h to form a nucleation layer, then heated to 600°C to 650°C and deposited for 1h to form an epitaxial film, thereby obtaining a single crystal spinel zinc gallate film.

2. The two-step method for preparing zinc gallate thin film according to claim 1, characterized in that: The molar ratio of gallium in the gallium acetylacetonate solution to zinc in the zinc acetylacetonate solution is 1:

1.

3. The two-step method for preparing zinc gallate thin film according to claim 1, characterized in that: The frequency of ultrasonic atomization treatment was 2.4 MHz.

4. The two-step method for preparing zinc gallate thin film according to claim 1, characterized in that: The flow rate of the inert gas is 5 L / min.

5. The two-step method for preparing zinc gallate thin film according to claim 1, characterized in that: The ultrasonic atomization treatment is carried out by using an ultrasonic atomizer; the distance between the pre-treated sapphire substrate and the reaction source nozzle of the ultrasonic atomizer is 10 mm.

6. The two-step method for preparing zinc gallate thin film according to claim 1, characterized in that: The stirring time is 6h.

7. A zinc gallate film prepared by the method according to any one of claims 1 to 6.

8. Use of the zinc gallate film according to claim 7 in the preparation of optoelectronic devices.

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