A high-purity gallium oxide and its preparation method

Abstract

This invention belongs to the field of semiconductor materials and discloses a high-purity gallium oxide and its preparation method. The preparation method includes: mixing ultrapure water and metallic gallium, performing a hydrothermal reaction with continuous stirring to obtain an intermediate product; washing and drying the intermediate product, and then heat-treating it in an oxygen-containing atmosphere to obtain the high-purity gallium oxide. This invention uses metallic gallium and ultrapure water as raw materials, and obtains gallium oxide through hydrothermal reaction, washing and drying, oxygen-containing atmosphere heat treatment, and gentle crushing. This method simplifies the raw material system, eliminates the addition of precipitants, complexing agents, mineralizing agents, and other organic or inorganic additives, effectively avoids the introduction of foreign ions and impurities, and can significantly improve the purity of the product.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor materials, and relates to a gallium oxide material, specifically a high-purity gallium oxide and its preparation method. Background Technology

[0002] Gallium oxide (GaO) is a promising next-generation ultrawide bandgap semiconductor material. Its core advantage lies in its ultrawide bandgap of approximately 4.9 eV, which grants it extremely high breakdown electric field strength. This allows for the fabrication of high-voltage, low-conduction-loss, high-efficiency power devices, theoretically outperforming current silicon, silicon carbide, and gallium nitride materials. Furthermore, GaO can be grown into single crystals using a low-cost melt-forming method, facilitating future large-scale production. In addition, GaO possesses excellent physicochemical stability and deep-ultraviolet light response characteristics, making it a promising candidate for applications in next-generation power electronics, deep-ultraviolet detection, and extreme environment applications.

[0003] Patent CN118255385A discloses a method for preparing filamentous gallium oxide nanoparticles. This method uses sodium bicarbonate as a precipitant, which is added dropwise to a gallium salt solution. After precipitation and room temperature aging, a precipitate is obtained. This precipitate is then washed, centrifuged, dried, ground, and sieved to obtain the precursor gallium hydroxyl oxide. Subsequently, it undergoes gradient heating calcination and cooling treatment to obtain filamentous gallium oxide. This method uses sodium bicarbonate as a precipitant, which introduces impurity ions such as sodium ions during the reaction. These ions require multiple washing and centrifugation processes to remove, increasing process complexity and potentially causing impurity residue. Furthermore, the process involves multiple steps, including precipitation, room temperature aging, washing, centrifugation, drying, grinding, sieving, gradient heating calcination, and cooling treatment. This lengthy process with numerous control points is not conducive to large-scale, stable production.

[0004] Patent CN120157172A discloses a method for preparing gallium oxide nanomaterials. Using gallium nitrate as the gallium source, GaOOH and β-Ga2O3 materials with good crystal quality and uniform phase are synthesized through a hydrothermal method and high-temperature calcination. This method requires a high-temperature, high-pressure, and closed system, placing high demands on equipment and imposing stringent operating conditions. Furthermore, organic or inorganic impurities are easily left in the hydrothermal reaction system, making complete removal difficult and affecting product purity. In addition, the combined process of hydrothermal method and subsequent high-temperature calcination involves numerous steps and high energy consumption, further increasing production costs and the risk of impurity introduction.

[0005] In summary, the existing technology for synthesizing gallium oxide is complex and requires the introduction of other reagents during the reaction, making it unsuitable for the preparation of high-purity gallium oxide. Summary of the Invention

[0006] In view of the defects and deficiencies of the existing technology, the present invention provides, firstly, a method for preparing high-purity gallium oxide; and secondly, a method for preparing high-purity gallium oxide.

[0007] In a first aspect, the present invention provides a method for preparing high-purity gallium oxide, comprising the following steps: Step 1: Mix ultrapure water and metallic gallium, perform a hydrothermal reaction and continue stirring to obtain an intermediate product; Step 2: After washing the intermediate product, dry it and then heat-treat it in an oxygen-containing atmosphere to obtain the high-purity gallium oxide.

[0008] Preferably, in step 1, the purity of gallium is greater than 5N.

[0009] Preferably, in step 1, the solid-liquid ratio of metallic gallium to ultrapure water is 0.05~0.15 g / mL.

[0010] Preferably, in step 1, the reaction temperature is 130~180℃, the reaction pressure is 0.3~1.0Mpa, and the reaction time is 5~20h.

[0011] Preferably, in step 1, the stirring speed is 200~400 rpm.

[0012] Preferably, in step 2, the intermediate product is washed alternately with ultrapure water and anhydrous ethanol until the conductivity of the washing solution is below 5 μS / cm.

[0013] Preferably, in step 2, the heat treatment temperature is 700~900℃ and the heat treatment time is 1~3h.

[0014] Preferably, in step 2, oxygen is continuously introduced into the reaction system during the heat treatment process to maintain the oxygen content in the reaction system at 80~100 vol%.

[0015] Preferably, in step 2, the solid particles obtained by heat treatment are further crushed and sieved to obtain the high-purity gallium oxide.

[0016] Secondly, the present invention provides a high-purity gallium oxide, wherein the purity of the gallium oxide is ≥99.999%.

[0017] Preferably, the gallium oxide is in the form of a rod, needle, or prism.

[0018] Compared with the prior art, the present invention has the following significant advantages: The high-purity gallium oxide preparation method provided by this invention uses metallic gallium and ultrapure water as raw materials. Gallium oxide is obtained through hydrothermal reaction, washing and drying, oxygen-containing atmosphere heat treatment and gentle crushing. This method simplifies the raw material system, without adding external precipitants, complexing agents, mineralizing agents and other organic or inorganic additives, effectively avoiding the introduction of foreign ions and impurities, and can significantly improve the purity of the product. At the same time, the process steps are simplified, the operating conditions are mild and controllable, no complex equipment and strict atmosphere control are required, the production cost is low and the process stability is good, making it suitable for large-scale preparation of high-purity gallium oxide materials. Attached Figure Description

[0019] Figure 1 The image shows the XRD pattern of the precursor powder obtained in step 3 of Example 1. Figure 2 The image shows the XRD pattern of the gallium oxide product finally obtained in Example 1. Figure 3 This is a SEM image of the gallium oxide product finally obtained in Example 1. Detailed Implementation

[0020] The present invention provides the following specific technical solutions.

[0021] In a first aspect, the present invention provides a method for preparing high-purity gallium oxide, comprising the following steps: Step 1: Mix ultrapure water and metallic gallium, perform a hydrothermal reaction and continue stirring to obtain an intermediate product; Step 2: After washing the intermediate product, dry it and then heat-treat it in an oxygen-containing atmosphere to obtain the high-purity gallium oxide.

[0022] The inventors discovered that this invention uses only metallic gallium and ultrapure water as reaction raw materials, without adding any precipitants, alkali sources, mineralizers, complexing agents, surfactants, or organic additives. This avoids the introduction of impurities such as sodium, potassium, ammonium, carbon, and chlorine, or organic residues, which are often introduced by ammonia, sodium hydroxide, ammonium bicarbonate, and organic template agents in traditional processes. This ensures high purity of the product from the source, significantly improving the crystal quality and electrical properties of gallium oxide, making it more suitable for high-end applications such as power devices and deep ultraviolet detection. Furthermore, the overall process of this invention only includes a sealed, heated hydrothermal reaction, washing, drying, heat treatment, and crushing. It eliminates the need for complex multi-step precursor preparation, precise pH control, or harsh high-temperature and high-pressure reaction environments. Uniform nucleation and crystal growth can be achieved through continuous stirring during the reaction. The process parameters are easy to control and have good repeatability, significantly reducing operational difficulty and equipment requirements. It eliminates the need for expensive vapor deposition, hydrothermal autoclaves, or precision epitaxial equipment, significantly reducing production costs.

[0023] In other words, the preparation method provided by the present invention has the advantages of readily available raw materials, fewer process steps, low energy consumption, and no complicated post-processing procedures. Moreover, the reaction conditions are mild, the safety is high, and it is easy to scale up production. It can achieve continuous and stable preparation, which solves the defects of the existing gallium oxide synthesis process, such as lengthy process, high cost, difficulty in controlling impurities, and difficulty in large-scale production. It is conducive to industrialization and market application.

[0024] Preferably, in step 1, the solid-liquid ratio of metallic gallium to ultrapure water is 0.05~0.15 g / mL.

[0025] The inventors discovered that within the aforementioned preferred ratio range, the reaction kinetics of gallium metal and ultrapure water are stable, ensuring sufficient gallium reaction while avoiding problems such as raw material residue, uneven nucleation, or particle agglomeration caused by solid-liquid ratio imbalance. If the solid-liquid ratio is below 0.05 g / mL, excess ultrapure water will significantly reduce the effective concentration of gallium in the reaction system, significantly prolong the reaction time, and easily lead to precursor particle agglomeration, damaging the product's dispersibility and microstructure. If the solid-liquid ratio is above 0.15 g / mL, excess gallium metal will cause some gallium metal to fail to react completely, with unreacted gallium metal remaining as impurities in the product, directly reducing the purity of gallium oxide. At the same time, excess gallium metal will cause the local reaction to be too intense, producing impurities such as low-valence gallium oxide, affecting the crystallization quality of the product.

[0026] Preferably, in step 1, the reaction temperature is 130~180℃, the reaction pressure is 0.3~1.0Mpa, and the reaction time is 5~20h.

[0027] Through research, the inventors discovered that under the above-mentioned preferred conditions, controlling the reaction rate between metallic gallium and ultrapure water to be moderate and the nucleation and growth process to be uniform and controllable not only ensures that the reaction proceeds fully and obtains a gallium hydroxyl oxide precursor with good uniformity, but also avoids side reactions and impurity phase formation caused by high temperature and high pressure. At the same time, the parameters are mild, have low equipment requirements, and have good process stability, which is conducive to large-scale production and ensures the high purity and crystal quality of the final gallium oxide product.

[0028] Preferably, in step 1, the stirring speed is 200~400 rpm.

[0029] Through research, the inventors discovered that continuous stirring during the hydrothermal reaction process can make the metallic gallium and ultrapure water mix more evenly, avoiding uneven nucleation, particle agglomeration, or incomplete reaction caused by local concentration or temperature differences. At the same time, it promotes the timely diffusion of gases or byproducts generated in the reaction, making the kinetics of the entire reaction system more stable. This results in a precursor with uniform particle size, good dispersibility, and higher purity, providing a guarantee for the subsequent preparation of high-quality high-purity gallium oxide.

[0030] Preferably, in step 2, the intermediate product is washed alternately with ultrapure water and anhydrous ethanol until the conductivity of the washing solution is below 5 μS / cm.

[0031] The inventors discovered that thorough washing of the intermediate products can effectively remove soluble byproducts and trace ionic impurities generated during the reaction. Combined with subsequent oxygen-containing heat treatment, this further achieves complete decomposition and oxidation of organic residues, while simultaneously promoting the transformation of the precursor into highly crystalline β-type precursors. The Ga2O3 phase is completely converted, ultimately yielding gallium oxide products with high purity, good crystallinity, and extremely low impurity content, meeting the stringent purity requirements of high-end semiconductor materials.

[0032] Preferably, in step 2, the heat treatment temperature is 700~900℃ and the heat treatment time is 1~3h.

[0033] The inventors discovered that within the aforementioned preferred temperature and time range, the gallium hydroxyl oxide precursor can be completely dehydrated and transformed into a highly crystalline pure phase β-Ga2O3, while thoroughly decomposing trace organic residues without causing excessive growth or agglomeration of gallium oxide grains. If the heat treatment temperature is below 700℃ or the time is less than 1 hour, the gallium hydroxyl oxide is not completely dehydrated, has a low degree of crystallization, and is prone to leaving precursor phase residues. The product has poor crystallinity and poor electrical properties, which cannot meet the requirements of semiconductor device applications. If the heat treatment temperature is above 900℃ or the time exceeds 3 hours, it will cause excessive agglomeration and growth of gallium oxide grains, destroying the uniformity of the product's microstructure. At the same time, excessively high temperatures will significantly increase energy consumption and production costs, and may even trigger the thermal decomposition of gallium oxide, producing low-valence gallium oxide impurity phases, reducing product purity and performance.

[0034] Preferably, in step 2, oxygen is continuously introduced into the reaction system during the heat treatment process to maintain the oxygen content in the reaction system at 80~100 vol%.

[0035] Through research, the inventors discovered that continuously introducing oxygen and maintaining the oxygen content of the system during heat treatment can ensure that the intermediate product is fully oxidized and completely transformed into a high-purity β-Ga2O3 phase, avoiding the formation of impurity phases such as low-valence gallium oxides due to oxygen deficiency. At the same time, it promotes the complete decomposition of trace organic or carbonaceous residues, further improving the purity and crystal integrity of the product, so that the final gallium oxide has better electrical properties and stability.

[0036] Preferably, in step 2, the solid particles obtained by heat treatment are further crushed and sieved to obtain the high-purity gallium oxide.

[0037] Secondly, the present invention provides a high-purity gallium oxide, wherein the purity of the gallium oxide is ≥99.999%.

[0038] Preferably, the gallium oxide is in the form of a rod, needle, or prism.

[0039] To make the technical problems, technical solutions and technical advantages of the present invention clearer, a detailed description will be given below with reference to specific examples. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0040] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0041] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0042] Example 1: A method for preparing high-purity gallium oxide includes the following steps: Step 1: Weigh 20.00 g of 5N grade metallic gallium and place it in a stainless steel reactor lined with polytetrafluoroethylene (PTFE). Add 200 mL of ultrapure water with a resistivity ≥ 18.2 MΩ·cm. Line the reactor with PTFE and place it inside a high-pressure reactor equipped with a magnetic stirrer. Seal the reactor and heat the reaction system to 130°C at a pressure of 0.3 MPa. Maintain the reaction temperature for 20 hours under continuous stirring (300 rpm).

[0043] Step 2: After the reaction is complete, wait for the reactor to cool naturally to room temperature, then open the reactor and transfer all the obtained white suspension slurry to a centrifuge for solid-liquid separation. Then, wash the precipitate with high-purity water and anhydrous ethanol alternately. The washing process is judged by the endpoint criterion that the conductivity of the washing liquid is less than 5 μS / cm.

[0044] Step 3: Place the washed precipitate in a clean alumina crucible and dry it in a vacuum drying oven at 80°C for 6 hours to obtain loose gallium hydroxyl oxide precursor powder.

[0045] Step 4: Transfer the gallium hydroxyl oxide precursor powder to a calcination furnace, raise the temperature from room temperature to 800°C at a rate of 5°C / min, and maintain this temperature for 2 hours. During the reaction, continuously introduce oxygen into the calcination furnace at a rate of 200 mL / min to maintain the oxygen concentration in the calcination furnace at 100 vol%.

[0046] Step 5: Place the light yellow solid particles obtained after calcination into a hammer mill for pulverization, and then pass the pulverized powder through a 400-mesh standard sieve. The material passing through the sieve is high-purity β-Ga2O3 powder, which is then packed into an aluminum-plastic composite vacuum packaging bag, filled with inert gas, sealed, and stored in a dry and cool place.

[0047] Figure 1 The image shown is the XRD pattern of the precursor powder obtained in step 3 of Example 1. Figure 1 It can be seen that the characteristic diffraction peaks of the product are sharp and have high intensity. The positions of all diffraction peaks are highly consistent with the standard spectrum of the standard PDF card 54-0910 for gallium hydroxyoxide. There are no obvious impurity peaks or amorphous diffuse peaks, indicating that the intermediate product is a highly crystalline pure phase gallium hydroxyoxide without the introduction of other impurity phases.

[0048] Figure 2 The image shown is the XRD pattern of the gallium oxide product finally obtained in Example 1. Figure 2It can be seen that the characteristic diffraction peaks of the product are sharp and have high intensity. The positions of all diffraction peaks are highly consistent with the standard PDF card of β-Ga2O3. No obvious impurity peaks or amorphous diffuse peaks appear, indicating that the gallium oxide prepared by this invention is a highly crystalline pure phase β-Ga2O3 with no impurity phase residue. This fully demonstrates the advantages of this synthesis process in ensuring high purity and crystal integrity of the product.

[0049] Figure 3 The image shown is a SEM image of the gallium oxide product finally obtained in Example 1. Figure 3 It can be seen that the product exhibits a regular rod-shaped and prismatic crystal morphology, with slender particles, smooth surfaces and clear geometric shapes. The size distribution of individual rods is at the micrometer level, with good overall dispersion and no obvious hard agglomeration.

[0050] Example 2: A method for preparing high-purity gallium oxide includes the following steps: Step 1: Weigh 20.00 g of 5N grade metallic gallium and place it in a stainless steel reactor lined with polytetrafluoroethylene (PTFE). Add 250 mL of ultrapure water with a resistivity ≥ 18.2 MΩ·cm. Line the reactor with PTFE and place it inside a high-pressure reactor equipped with a magnetic stirrer. Seal the reactor and heat the reaction system to 150°C at a pressure of 0.6 MPa. Maintain the reaction temperature for 12 hours under continuous stirring (250 rpm).

[0051] Step 2: After the reaction is complete, wait for the reactor to cool naturally to room temperature, then open the reactor and transfer all the obtained white suspension slurry to a centrifuge for solid-liquid separation. Then, wash the precipitate with high-purity water and anhydrous ethanol alternately. The washing process is judged by the endpoint criterion that the conductivity of the washing liquid is less than 5 μS / cm.

[0052] Step 3: Place the washed precipitate in a clean alumina crucible and dry it in a vacuum drying oven at 80°C for 6 hours to obtain loose gallium hydroxyl oxide precursor powder.

[0053] Step 4: Transfer the gallium hydroxyl oxide precursor powder to a calcination furnace, raise the temperature from room temperature to 750°C at a rate of 5°C / min, and maintain this temperature for 1.5 hours. During the reaction, continuously introduce oxygen into the calcination furnace at a rate of 200 mL / min to maintain the oxygen concentration in the calcination furnace at 90 vol%.

[0054] Step 5: Place the light yellow solid particles obtained after calcination into a hammer mill for pulverization, and then pass the pulverized powder through a 400-mesh standard sieve. The material passing through the sieve is high-purity β-Ga2O3 powder, which is then packed into an aluminum-plastic composite vacuum packaging bag, filled with inert gas, sealed, and stored in a dry and cool place.

[0055] Example 3: A method for preparing high-purity gallium oxide includes the following steps: Step 1: Weigh 20.00 g of 5N grade metallic gallium and place it in a stainless steel reactor lined with polytetrafluoroethylene (PTFE). Add 150 mL of ultrapure water with a resistivity ≥ 18.2 MΩ·cm. Line the reactor with PTFE and place it inside a high-pressure reactor equipped with a magnetic stirrer. Seal the reactor and heat the reaction system to 150°C at a pressure of 0.6 MPa. Maintain the reaction temperature for 5 hours under continuous stirring (400 rpm).

[0056] Step 2: After the reaction is complete, wait for the reactor to cool naturally to room temperature, then open the reactor and transfer all the obtained white suspension slurry to a centrifuge for solid-liquid separation. Then, wash the precipitate with high-purity water and anhydrous ethanol alternately. The washing process is judged by the endpoint criterion that the conductivity of the washing liquid is less than 5 μS / cm.

[0057] Step 3: Place the washed precipitate in a clean alumina crucible and dry it in a vacuum drying oven at 80°C for 6 hours to obtain loose gallium hydroxyl oxide precursor powder.

[0058] Step 4: Transfer the gallium hydroxyl oxide precursor powder to a calcination furnace and raise the temperature from room temperature to 880°C at a rate of 5°C / min. Maintain this temperature for 2.5 hours. During the reaction, continuously introduce oxygen into the calcination furnace at a rate of 200 mL / min to maintain the oxygen concentration in the furnace at 85 vol%.

[0059] Step 5: Place the light yellow solid particles obtained after calcination into a hammer mill for pulverization, and then pass the pulverized powder through a 400-mesh standard sieve. The material passing through the sieve is high-purity β-Ga2O3 powder, which is then packed into an aluminum-plastic composite vacuum packaging bag, filled with inert gas, sealed, and stored in a dry and cool place.

[0060] Comparative Example 1: A method for preparing high-purity gallium oxide, which differs from Example 1, is as follows: In step 1, 20.00 g of 5N grade metallic gallium is weighed and placed in a stainless steel reactor lined with polytetrafluoroethylene (PTFE), and 200 mL of ultrapure water with a resistivity ≥18.2 MΩ·cm is added. The PTFE-lined reactor is then placed into a high-pressure reactor equipped with a magnetic stirrer and sealed. The reaction system is then heated to 130°C at a reaction pressure of 0.3 MPa.

[0061] Steps 2-5 are the same as in Example 1.

[0062] Comparative Example 2: A method for preparing high-purity gallium oxide includes the following steps: Steps 1-3 are the same as in Example 1. Step 4: Transfer the gallium hydroxyl oxide precursor powder to a calcination furnace, raise the temperature from room temperature to 650°C at a rate of 5°C / min, and maintain this temperature for 2 hours. During the reaction, continuously introduce oxygen into the calcination furnace at a rate of 200 mL / min to maintain an oxygen concentration of 100 vol%. Step 5 is the same as in Example 1.

[0063] Comparative Example 3: A method for preparing high-purity gallium oxide includes the following steps: Steps 1-3 are the same as in Example 1. Step 4: Transfer the gallium hydroxyl oxide precursor powder to a calcination furnace, raise the temperature from room temperature to 1000℃ at a rate of 5℃ / min, and maintain this temperature for 2 hours. During the reaction, continuously introduce oxygen into the calcination furnace at a rate of 200 mL / min to maintain the oxygen concentration in the calcination furnace at 100 vol%. Step 5 is the same as in Example 1.

[0064] Comparative Example 4: A method for preparing high-purity gallium oxide, differing from Example 1, involves the following steps: In step 1, 20.00 g of 5N grade metallic gallium is weighed and placed in a stainless steel reactor lined with polytetrafluoroethylene (PTFE), and 100 mL of ultrapure water with a resistivity ≥18.2 MΩ·cm is added. The PTFE-lined reactor is then placed into a high-pressure reactor equipped with a magnetic stirrer and sealed. The reaction system is then heated to 130°C at a reaction pressure of 0.3 MPa. The reaction is carried out at a constant temperature for 20 h under continuous stirring (300 rpm).

[0065] Steps 2-5 are the same as in Example 1.

[0066] Comparative Example 5: A method for preparing high-purity gallium oxide, differing from Example 1, involves the following steps: In step 1, 20.00 g of 5N grade metallic gallium is weighed and placed in a stainless steel reactor lined with polytetrafluoroethylene (PTFE), and 500 mL of ultrapure water with a resistivity ≥18.2 MΩ·cm is added. The PTFE-lined reactor is then placed into a high-pressure reactor equipped with a magnetic stirrer and sealed. The reaction system is then heated to 130°C at a reaction pressure of 0.3 MPa. The reaction is carried out at a constant temperature for 20 h under continuous stirring (300 rpm).

[0067] Steps 2-5 are the same as in Example 1.

[0068] The morphological characterization of the gallium oxide products obtained in Comparative Examples 1-3 and Comparative Examples 1-5 is shown in Table 1.

[0069] Table 1. Morphological characterization of gallium oxide obtained in Examples 1-3 and Comparative Examples 1-5 As shown in Table 1, the gallium oxide products of Examples 1-3 prepared under the preferred process parameters of the present invention all exhibit regular micron-sized rod-shaped, prismatic, or needle-shaped morphologies, with complete and regular crystal forms, smooth surfaces, and no agglomeration throughout the process. The particle size distribution is uniform and within a small range. However, the gallium oxide products of Comparative Examples 1-5, whose process parameters deviate from the preferred range of the present invention, all exhibit varying degrees of morphological defects, such as irregular blocks, incomplete or distorted crystal forms, or loss of rod-shaped features. They are also accompanied by different types and degrees of agglomeration problems, including severe hard agglomeration, molten agglomeration, and heavy soft agglomeration. There are cases of tight adhesion, fusion, or bonding between particles, which ultimately leads to a significant increase in product particle size and a wider distribution range.

[0070] Table 1 demonstrates that the preferred process parameters provided by this invention can prepare gallium oxide products with regular morphology, excellent dispersibility, and uniform particle size.

[0071] Gallium oxide obtained in Examples 1-3 and Comparative Examples 1-5 was used as a raw material to prepare gallium oxide thin films on an insulating substrate. A DC high voltage was applied to the thin films, and the critical electric field strength at which the thin films were broken down was recorded. The crystallinity of gallium oxide obtained in Examples 1-3 and Comparative Examples 1-5 was tested using X-ray diffraction; the purity of gallium oxide obtained in Examples 1-3 and Comparative Examples 1-5 was tested using inductively coupled plasma mass spectrometry. The test data are shown in Table 2.

[0072] Table 2 shows the purity, electrical properties, and crystallinity of gallium oxide obtained in Examples 1-3 and Comparative Examples 1-5. As shown in Table 2, the gallium oxide obtained in Examples 1-3 all reached a purity of 5N (≥99.999%), and the crystallinity was maintained above 98.0%. The corresponding breakdown electric field strength was ≥8.2MV / cm, exhibiting excellent intrinsic electrical performance. In contrast, the gallium oxide products obtained in Comparative Examples 1-5 all had a purity of 4N or below, and the crystallinity also decreased significantly to below 87.0%. At the same time, their breakdown electric field strength was greatly reduced to below 5.5MV / cm, which was far lower than the level of the examples. This performance difference is directly related to the powder morphology. The gallium oxide obtained in Examples 1-3 has a regular micron-sized rod-shaped, prismatic, or needle-shaped morphology with complete crystal structure, smooth surface, and no agglomeration. This morphological feature ensures that the crystal lattice is orderly, the defect density is low, and oxygen is fully contacted during calcination and impurities are easily removed during washing, thus achieving high purity and high crystallinity. In contrast, the gallium oxide in Comparative Examples 1-5 is irregular blocky, distorted crystal, or agglomerated, accompanied by problems such as blurred grain boundaries and particle adhesion and fusion. This not only leads to lattice distortion and impurity adsorption residue during crystal growth, but also significantly reduces the purity and crystallinity of the product due to insufficient oxygen penetration and a sharp increase in defect density inside the agglomerates. Ultimately, this results in a decrease in the carrier transport efficiency of the gallium oxide film, an easy concentration of electric field at defects, and a significant decrease in the breakdown electric field strength. As shown in Table 2, the preparation method and optimized process parameters provided by this invention can precisely control the morphology of gallium oxide powder, thereby effectively ensuring the high purity and high crystallinity of gallium oxide and improving the electrical performance of gallium oxide films from the structural source.

[0073] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope of the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity gallium oxide, characterized in that, Includes the following steps: Step 1: Mix ultrapure water and metallic gallium, perform a hydrothermal reaction and continue stirring to obtain an intermediate product; Step 2: After washing the intermediate product, dry it and then heat-treat it in an oxygen-containing atmosphere to obtain the high-purity gallium oxide.

2. The method for preparing high-purity gallium oxide as described in claim 1, characterized in that, In step 1, the reaction temperature is 130~180℃, the reaction pressure is 0.3~1.0Mpa, and the reaction time is 5~20h.

3. The method for preparing high-purity gallium oxide as described in claim 1 or 2, characterized in that, In step 1, the solid-liquid ratio of metallic gallium to ultrapure water is 0.05~0.15 g / mL; the stirring rate is 200~400 rpm.

4. The method for preparing high-purity gallium oxide as described in claim 1, characterized in that, In step 2, the heat treatment temperature is 700~900℃ and the heat treatment time is 1~3h.

5. The method for preparing high-purity gallium oxide as described in claim 1 or 4, characterized in that, In step 2, oxygen is continuously introduced into the reaction system during the heat treatment process to maintain the oxygen content in the reaction system at 80~100 vol%.

6. The method for preparing high-purity gallium oxide as described in claim 1 or 4, characterized in that, In step 2, the intermediate product is washed alternately with ultrapure water and anhydrous ethanol until the conductivity of the washing solution is below 5 μS / cm.

7. The method for preparing high-purity gallium oxide as described in claim 1, characterized in that, In step 2, the solid particles obtained by heat treatment are crushed and sieved to obtain the high-purity gallium oxide.

8. The method for preparing high-purity gallium oxide as described in claim 1, characterized in that, In step 1, the purity of the gallium metal is greater than 5N.

9. A high-purity gallium oxide, characterized in that, The gallium oxide is prepared by the preparation method according to any one of claims 1 to 8, wherein the purity of the gallium oxide is ≥99.999%.

10. The method for preparing high-purity gallium oxide as described in claim 9, characterized in that, The gallium oxide is in the form of rods, needles, or prisms.

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