A low-defect gallium oxide single crystal pulling growth equipment and method based on double-cavity atmosphere regulation

Abstract

This application relates to the field of semiconductor material growth technology, aiming to solve the technical problems in the prior art, such as reduced heating element lifespan due to a single shared atmosphere, numerous crystal defects making quality assurance difficult, and high single crystal production costs but low production efficiency. The single crystal growth apparatus disclosed in this application is characterized by comprising a furnace body, a first chamber, a second chamber, a heating component, a growth component, an atmosphere isolation and heat conduction component, an atmosphere management system, and a central control system; the atmosphere isolation and heat conduction component is used to divide the furnace body into a hermetically isolated first chamber and a second chamber and to efficiently transfer heat. By adopting the above solution, this application can achieve atmosphere structure separation and a combined crucible design, effectively extending the lifespan of the heating element while ensuring high crystal quality and purity, and significantly reducing operating costs.

Description

Technical Field

[0001] This invention relates to the field of ultra-wide bandgap semiconductor material preparation technology, and in particular to a manufacturing equipment and method for low-defect gallium oxide single crystals. Background Technology

[0002] Gallium oxide (Ga2O3), as an ultrawide bandgap semiconductor material, possesses outstanding advantages such as a large bandgap (approximately 4.9 eV) and high breakdown electric field strength (approximately 8 MV / cm). Its Baliga figure of merit (BFOM) is significantly superior to that of traditional semiconductor materials, making it a promising candidate for applications in high-power electronic devices and solar-blind ultraviolet optoelectronic devices. Furthermore, unlike silicon carbide, gallium nitride, and diamond, which typically employ vapor-phase methods with growth rates of only about 0.1 mm / h, gallium oxide single crystals can be prepared using melt methods such as Czochralski, Vertical Bridgman (VB), Edge-defined Film-fed Growth (EFG), and casting, achieving growth rates up to 10 mm / h. This significantly improves production efficiency and reduces production costs. Therefore, gallium oxide is considered by the industry to be the most likely ultrawide bandgap semiconductor material to achieve large-scale commercialization first.

[0003] However, the large-size, high-quality growth of gallium oxide single crystals still faces many challenges. First, gallium oxide melt is extremely prone to decomposition and volatilization at high temperatures (melting point approximately 1790–1810 °C). To suppress decomposition, a certain oxygen partial pressure must be maintained in the growth environment. If the oxygen partial pressure is insufficient, the metallic gallium produced by melt decomposition will corrode the crucible, and the decomposition products may form floating debris, interfering with the crystallization and pulling processes. In addition, insufficient oxygen partial pressure will also lead to a high concentration of oxygen vacancy defects in the crystal, reducing the crystal quality and electrical properties.

[0004] Currently, commonly used melt methods (such as the Czochralski method and the mold-guided method) mostly use gases such as carbon dioxide to control the atmosphere and maintain the oxygen partial pressure below 4%. However, practice has shown that this method still cannot completely avoid the decomposition of gallium oxide melt, thus limiting the yield and quality of crystal growth. Secondly, existing gallium oxide crystal growth equipment is expensive. Traditional gallium oxide single crystal growth methods typically use a large amount of precious metals (such as iridium) as heating elements, crucibles, and molds. Iridium crucibles are usually more than 2 mm thick, and a single crystal growth furnace typically requires several kilograms of iridium, resulting in high costs. In addition, the complex structure of the hot zone and lifting system further contributes to the high cost of the equipment. At the same time, when operating at high temperatures in an oxygen-containing atmosphere, iridium and other crucible materials are inevitably oxidized and corroded, further increasing production costs. Some inventions replace the precious metal iridium crucible with an oxidation-resistant oxide crucible, such as zirconium oxide or aluminum oxide. This eliminates the need for iridium crucibles, reduces production costs, and increases oxygen partial pressure to reduce oxygen vacancy defects during gallium oxide single crystal growth. However, gallium oxide inevitably undergoes chemical reactions with other oxides to generate intermediate compounds, which can lead to excessive doping of gallium oxide single crystals with impurity elements, or even the formation of a second phase, making it impossible to obtain gallium oxide single crystals. Summary of the Invention

[0005] To address at least one of the aforementioned problems, this invention provides gallium oxide single crystal manufacturing equipment and manufacturing method thereof, achieving the technical effects of improving crystal growth yield and crystal quality, reducing the amount of precious metal crucible material used, extending the life of the heating system, and reducing production costs.

[0006] According to one aspect of the present invention, a gallium oxide single crystal manufacturing apparatus is provided, the apparatus being particularly suitable for growing low-defect gallium oxide single crystals using the Czochralski method or the mode-guided method, characterized in that it comprises:

[0007] A furnace body, wherein a cylindrical atmosphere separation and heat conduction assembly is provided inside the furnace body, the atmosphere separation and heat conduction assembly physically divides the internal space of the furnace body into a first chamber and a second chamber that are isolated from each other and arranged coaxially.

[0008] A protective heating system, the heating system including a heating element disposed in the first chamber, the surface of the heating element being provided with a protective coating;

[0009] An atmosphere control system includes a first atmosphere management unit connected to a first chamber for supplying and maintaining a protective atmosphere in the first chamber; and a second atmosphere management unit connected to a second chamber for supplying and maintaining an oxygen-containing atmosphere in the second chamber.

[0010] A temperature control system, comprising a first temperature management unit connected to a first chamber for regulating the temperature of the first chamber; and a second temperature management unit connected to a second chamber for regulating the temperature of the second chamber; and

[0011] A central control system, comprising a temperature sensor, a pressure sensor, an oxygen partial pressure sensor, and a central processing unit.

[0012] Furthermore, the atmosphere separation and heat conduction component is integrally formed from high-temperature resistant transparent ceramic with a wall thickness of 5mm to 15mm. The component material can be selected from zirconia transparent ceramic, magnesium aluminum spinel transparent ceramic, or sapphire.

[0013] Optionally, both the inner and outer surfaces of the atmosphere separation and heat conduction component are mirror-polished, with a surface roughness Ra of less than 0.2 μm.

[0014] Furthermore, the heating element body is selected from graphite, molybdenum disilicide, or tungsten alloy; the protective coating comprises at least one layer.

[0015] In one embodiment of the present invention, the heating element is a graphite heater, and the surface of the heater has a multi-layered composite protective coating, consisting of a transition layer, a main protective layer, and a self-healing layer from the inside out. The transition layer is boron nitride or silicon carbide, the main protective layer is tantalum metal or tantalum carbide, and the self-healing layer is an alumina layer doped with nano-silica.

[0016] In another embodiment of the present invention, the heating element is a honeycomb graphite heater.

[0017] In another embodiment of the present invention, the heating element is a molybdenum disilicide heater, and the silicon dioxide layer generated on the surface of the heater serves as its protective coating.

[0018] In another embodiment of the present invention, the heating element is a tungsten alloy heater, and the surface of the heater has a multi-layered composite protective coating, consisting of a transition layer and a main protective layer from the inside out. The transition layer is tantalum carbide, and the main protective layer is hafnium carbide.

[0019] In another embodiment of the invention, the heating element comprises at least three groups, respectively disposed in the upper / middle and lower parts of the furnace lining, forming multiple temperature fields within the furnace body to facilitate precise control of the crystal growth process by zone.

[0020] Furthermore, the manufacturing equipment of the present invention also includes a crystal growth system, the crystal growth system comprising a combined crucible disposed within the second chamber, the combined crucible comprising a crucible having a first inner diameter and a crucible support having a second inner diameter; the crucible is made of a chemically oxidizing material, has a wall thickness of 0.1-0.8 mm, and is used for heating and / or holding the molten material at high temperatures, and is detachably supported on the crucible support. The crucible support is made of a heat-resistant material, its bottom thickness is approximately 2 to 3 times the sidewall thickness, and its second inner diameter is approximately 10 to 50 times its sidewall thickness. The crucible and the crucible support are arranged coaxially; optionally, the second inner diameter is 1-3 mm larger than the first inner diameter, thereby forming an annular gap between the outer wall of the crucible and the inner wall of the crucible support.

[0021] In one embodiment of the invention, the crucible is made of a material selected from platinum, a platinum-rhodium alloy, or a platinum-iridium alloy. In the platinum-rhodium alloy, the rhodium content is greater than or equal to 10 wt%. In the platinum-iridium alloy, the iridium content is greater than or equal to 15 wt%.

[0022] In another embodiment of the invention, the crucible is made of high-temperature resistant magnesium oxide or zirconium oxide.

[0023] In another embodiment of the invention, the crucible is made of iridium and a dense zirconium oxide layer is formed on its surface by a plasma spraying process, the dense zirconium oxide layer having a thickness of about 100-200 μm.

[0024] In another embodiment of the invention, the crucible support is made of high-temperature resistant alumina, magnesium oxide, or zirconium oxide.

[0025] Optionally, a coaxially arranged thermally conductive layer and / or adaptive pressure compensation layer are disposed within the annular void. The thermally conductive layer serves to create good heat conduction between the crucible and the crucible support, eliminating or avoiding radial temperature differences. The thermally conductive layer can be composed of silicon carbide nanowire arrays, hollow ceramic spheres, etc. The adaptive pressure compensation layer is used to dissipate or avoid compressive stress caused by the difference in thermal expansion coefficients between the crucible and the crucible support. The adaptive pressure compensation layer can be made of nickel-titanium shape memory alloy fiber felt or ceramic fiber, wherein 5%-10% cerium oxide nanoparticles are doped into the alloy fiber felt or ceramic fiber.

[0026] Furthermore, the manufacturing equipment of the present invention also includes an annular sealing cover, which is mounted on the upper opening of the atmosphere isolation and heat conduction component and the furnace lining, and together with the atmosphere isolation and heat conduction component and the furnace lining, constitutes the first chamber. The annular sealing cover has a third inner diameter and a fourth inner diameter smaller than the third inner diameter; and an upper cover, which is installed on the top of the annular sealing cover and has a first diameter and a second diameter that mechanically cooperate with the annular sealing cover, wherein the first diameter is larger than the second diameter.

[0027] In an embodiment of the present invention, the annular sealing cap and the top cover are made of high-temperature resistant ceramic materials, such as the annular sealing cap being made of magnesium oxide, aluminum oxide or zirconium oxide, and the top cover being made of aluminum oxide hollow spheres or zirconium oxide fiber bricks.

[0028] Furthermore, the first atmosphere management unit in the technical solution of the present invention includes a pressure detection module for real-time monitoring of the pressure in the first chamber. The second atmosphere management unit includes a multi-gas source module and a pressure detection module; the multi-gas source module includes an inert gas source and an oxygen-containing gas source, and the gas flow rate is controlled by a dual-channel flow controller, with a flow rate adjustment range of 10-50 L / h. The pressure detection module includes a pressure sensor disposed inside the second chamber for real-time detection of the pressure and oxygen partial pressure inside the second chamber.

[0029] Furthermore, the apparatus for growing gallium oxide single crystals of the present invention further includes: an integrated temperature monitoring system, the integrated temperature monitoring system including: an infrared thermometer, which measures the temperature inside the crucible in the crystal growth system non-contactly through an optical window set on the top of the furnace body; and an infrared thermal imaging feedback unit, including a high-resolution infrared camera, set outside the observation window of the first chamber, which acquires images of the temperature distribution of the melt surface and the solid-liquid interface in real time through the atmosphere separation and heat conduction components.

[0030] In an embodiment of the present invention, the optical window is located on the side wall of the furnace lining and is typically made of a high-temperature resistant transparent material, such as quartz glass or sapphire, to facilitate the operator's observation of the melt and crystal growth inside the furnace.

[0031] In another embodiment of the invention, the integrated temperature monitoring system further includes a thermocouple, which serves as a temperature sensor and is disposed within the first chamber. The measuring end of the thermocouple is in close contact with the outer wall of the atmosphere separation and heat conduction component. This arrangement forms a dual independent temperature control system within the entire single crystal growth equipment, with the first and second chambers controlling the temperature within their respective areas. This helps extend the lifespan of the heater while ensuring the growth environment and quality level of the single crystal.

[0032] Furthermore, the crystal growth system also includes a drive mechanism installed above the upper cover, comprising a seed crystal chuck and a lifting and rotating mechanism for holding the seed crystal and rotating and slowly lifting it during the crystal growth process.

[0033] Furthermore, the central control system is electrically connected and communicates with the protective heating system, the drive mechanism of the crystal growth system, the atmosphere control system, and the integrated temperature detection system. The central control system has a built-in differential pressure control algorithm, which adjusts the heating power of the protective heating system, the displacement speed of the drive mechanism of the crystal growth system, the gas flow rate and pressure of the atmosphere control system, and the temperature of each temperature zone in real time based on the collected data.

[0034] According to a second aspect of the present invention, a method for growing low-defect gallium oxide single crystals based on the above-described apparatus is also provided, characterized by comprising the following steps:

[0035] S1. Loading: Load the high-purity gallium oxide raw material into the crucible and place it in the center of the second chamber.

[0036] S2. Chamber atmosphere initialization: Inert gas is introduced into the first chamber to atmospheric pressure or slightly positive pressure, and oxygen-containing gas is introduced into the second chamber to make the oxygen partial pressure reach a preset value; the pressure difference between the first chamber and the second chamber is kept below a preset threshold; the preset threshold is below 10 kPa, and optionally below 5 kPa.

[0037] S3. Melt preparation: Start the protective heating system and raise the temperature in the crucible to the first temperature through the heating element. Maintain the temperature for a certain period of time to completely melt the gallium oxide raw material. The first temperature shall not be lower than the melting point of gallium oxide.

[0038] S4. Crystal Growth: In this step, dynamic atmosphere adjustment is performed. Based on feedback from the temperature monitoring system and the gas pressure detection module, the oxygen content in the oxygen-containing gas is adjusted in real time. During the crystal introduction stage, the crystal grows at the first temperature, maintaining the oxygen volume ratio at 0-10%. During the crystal growth stage, the crystal grows at the second temperature, maintaining the oxygen volume ratio at 15-25%. After the crystal growth is completed, the temperature is gradually lowered to the third temperature, gradually reducing the oxygen volume ratio from 10% to 0.

[0039] In one embodiment of the present invention, the equipment is used for the Czochralski method to grow gallium oxide single crystals. The crystal growth process is divided into three stages: crystal pulling and necking, shoulder-forming and constant-diameter growth, and tail-end cooling. Crystal pulling and necking are performed at a first temperature, and the driving mechanism has a first pulling speed and a first rotational speed. Entering the shoulder-forming and constant-diameter growth stage, a second temperature is equal to or lower than the first temperature, and the driving mechanism has a second pulling speed and a second rotational speed. Entering the tail-end cooling stage, a third temperature is lower than the second temperature, and the driving mechanism has a third pulling speed and a third rotational speed. Preferably, the product of the pulling speed and the rotational speed is kept within the range of 1-10 mm·rpm / h in each stage.

[0040] S5. Cooling and pressure control of the first chamber: After the second chamber starts cooling for a certain period of time, the first chamber begins to cool down at a rate equal to or lower than that of the second chamber, and the temperature difference between the first and second chambers is kept within 30°C. When the temperature in the first chamber drops to the oxidation critical temperature of the heating element, the inert gas flow rate is gradually reduced. When the temperature difference between the first chamber and the outside air temperature is below 200°C and the pressure in the first chamber is equal to the outside air pressure, the inert gas is shut off.

[0041] In one embodiment of the invention, a graphite heater or a sponge-like graphite heater is used. When the temperature in the first chamber drops to 800°C, the inert gas flow rate is gradually reduced. At this time, a slight positive pressure is maintained to prevent backflow of outside air.

[0042] In another embodiment of the invention, a tantalum-tungsten alloy heater is used, and the inert gas flow rate is gradually reduced when the temperature in the first chamber drops to 1200°C.

[0043] During the crystal growth process in steps S3 to S5, the solid-liquid interface temperature distribution is monitored in real time using an infrared thermal imaging feedback unit. The central control system optimizes the oxygen-argon ratio and heating power based on temperature, partial pressure changes, and pulling speed parameters, so that the axial temperature gradient inside the furnace is stabilized at 5-8℃ / cm and the radial temperature gradient is stabilized within 1-5℃.

[0044] S6. Crystal Removal: After the crystal has cooled to room temperature, remove the crystal.

[0045] According to a third aspect of the present invention, gallium oxide single crystals obtained by the manufacturing equipment and growth method of the present invention are provided. These gallium oxide single crystals are crack-free, transparent, and have a minimum crystal defect density of <5×10⁻⁶. 3 cm -2 .

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] First, by incorporating an atmosphere isolation and heat conduction component made of a highly dense, high-temperature resistant, and thermally conductive ceramic material, this invention structurally achieves physical isolation and airtight separation between the first and second chambers. This dual-chamber structure fundamentally resolves the conflict in atmospheric requirements between the heating element and the crystal growth environment in traditional single-chamber devices. By independently introducing and maintaining a high-concentration oxidizing atmosphere in the second chamber, the growth quality of gallium oxide single crystals is significantly improved. By introducing and maintaining an inert or weakly reducing protective atmosphere in the first chamber, the oxidation and degradation rate of the heating element under ultra-high temperature conditions is greatly slowed down.

[0048] Secondly, by introducing low-cost non-precious metal heating elements and improving the iridium crucible, this invention reduces the use of a large amount of iridium or even completely adopts iridium-free crucibles for single crystal growth, significantly reducing equipment manufacturing costs and extending the service life of the heating system.

[0049] Third, the present invention implements dual-path precise atmosphere control and an independent dual-temperature control system, which effectively reduces oxygen vacancy defects in the crystal and improves the integrity and purity of gallium oxide single crystal; at the same time, it achieves atmosphere protection for the graphite heater, extending its service life by tens or even hundreds of times, thereby significantly improving the operational stability and reliability of the equipment.

[0050] Fourth, the unique method for precise differential pressure control between the inner and outer chambers in this invention constitutes an active process safety barrier. By maintaining a slight positive pressure on the outside of the inner chamber, it ensures that any potential micro-leakage of gas will only flow from the high-purity growth atmosphere to the protective atmosphere, absolutely avoiding contamination of the crystal growth environment by the protective atmosphere and guaranteeing the high purity of the crystal. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments of this disclosure will be briefly introduced below. Obviously, the drawings described below are merely some exemplary embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the content of the exemplary embodiments of this disclosure and these drawings without any creative effort.

[0052] Figure 1 This is a schematic diagram of the equipment for growing gallium oxide single crystals in an embodiment of the present invention;

[0053] Figure 2 This is a schematic diagram of the combined crucible structure in an embodiment of the present invention;

[0054] Figure 3 This is a schematic diagram of the equipment for growing gallium oxide single crystals according to another embodiment of the present invention.

[0055] Figure 4 This is a schematic diagram of the structure of a combined crucible in another embodiment of the present invention;

[0056] In the picture:

[0057] 1-Furnace lining, 2-Induction coil, 3-Heater, 4-First air inlet, 5-First air outlet, 6-Atmosphere separation and heat conduction assembly, 7-Annular sealing cover, 8-Top cover, 9-Second air inlet, 10-Second air outlet, 11-Crystal growth driving mechanism, 12-Observation window, 13-Integrated temperature monitoring system, 14-Combined crucible, 15-Heat-conducting layer, 16-Pressure compensation layer, 100-Crucible support, 101-Crucible. Detailed Implementation

[0058] The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present disclosure and are not intended to limit the scope of the disclosure.

[0059] To keep the drawings concise, each drawing only schematically shows the parts relevant to the disclosure; these do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one," and "several" includes "two" and "more than two."

[0060] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0061] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0062] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of description and simplification of operation, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0063] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0064] Example 1

[0065] like Figures 1-2 As shown, it illustrates a gallium oxide single crystal growth apparatus in one embodiment of this application.

[0066] First see Figure 1 , Figure 1 This is a schematic diagram of the gallium oxide single crystal growth equipment in this embodiment. The equipment has a furnace lining 1 inside the furnace shell, made of high-temperature resistant materials such as magnesium oxide or aluminum oxide, providing a suitable radial temperature gradient for gallium oxide single crystal growth. An induction coil 2 surrounds the outside of the furnace lining and is used to generate an alternating magnetic field to inductively heat the heating element 3.

[0067] A cylindrical atmosphere separation and heat conduction component 6 is installed inside the furnace body. The component has a wall thickness of 5mm to 15mm and is located in the center of the furnace body. It physically divides the internal space of the furnace body into a first chamber and a second chamber that are isolated from each other and arranged coaxially.

[0068] In some examples of the present invention, the atmosphere separation and heat conduction component 6 is integrally formed from a high-temperature resistant transparent ceramic material with a purity of 99.8% or higher, such as zirconia transparent ceramic, magnesium aluminum spinel transparent ceramic, or sapphire, through hydrostatic pressing and high-temperature sintering. The ceramic body prepared by this process can stably achieve a density of 3.89 g / cm³. 3 The above features excellent high-temperature mechanical properties, good mid-infrared transmittance, and extremely low gas permeability.

[0069] In one specific embodiment, the atmosphere separation and heat conduction component 6 is made of sapphire, with both its inner and outer surfaces mirror-polished to a surface roughness Ra below 0.2 μm, and a cylinder wall thickness of 15 mm. Testing has verified that, at extreme operating temperatures up to 1850°C, the permeability of component 6 for key process gases such as inert gases and oxygen is less than 10%. - 8 Pa·m 3 / s, forming a reliable atmospheric isolation barrier. At the same time, sapphire maintains a thermal conductivity greater than 5W / (m·K) within this temperature range, ensuring that heat can be efficiently and uniformly transferred from the second chamber to the first chamber.

[0070] A protective heating system is installed in the first chamber. This system includes heater elements 3 with at least one protective coating on their surface. The heater elements 3 are evenly distributed in the annular space between the furnace lining 1 and the outer wall of the heat conduction component 6. To protect the heater elements 3 from the oxygen atmosphere, a protective gas, such as an inert gas, is continuously introduced into the first chamber through a first air inlet 4 located at the bottom of the substrate. An annular sealing cover is provided at the top of the first chamber, and a first air outlet 5 is provided at the top of the annular sealing cover to discharge the protective gas in the first chamber and maintain the pressure stability of the first chamber.

[0071] In some examples of the present invention, the heating element body material is selected from graphite, especially honeycomb graphite, molybdenum disilicide or tungsten alloy, and the surface of the heating element includes at least one protective coating, which can further improve the temperature distribution uniformity of the heating element and improve its service life.

[0072] In one specific embodiment, the heating element is a graphite heater, and the surface of the heater has a multi-layered composite protective coating, consisting of a transition layer, a main protective layer, and a self-healing layer from the inside out. The transition layer is boron nitride or silicon carbide, the main protective layer is tantalum metal or tantalum carbide, and the self-healing layer is an aluminum oxide layer doped with nano-silica.

[0073] In another specific embodiment, the heating element is a tungsten alloy heater, and the surface of the heater has a multi-layered composite protective coating, consisting of a transition layer and a main protective layer from the inside out. The transition layer is tantalum carbide, and the main protective layer is hafnium carbide.

[0074] In some examples of the present invention, multiple sets of heating elements are included, for example, at least three sets of heating elements are evenly distributed in the upper / middle / lower part of the furnace lining to form multiple temperature fields in the furnace body, so as to achieve precise temperature control of each temperature zone.

[0075] The second chamber is enclosed by an atmosphere separation and heat conduction assembly 6 and a top cover 8, and houses a crystal growth system. This crystal growth system includes a combined crucible and melt, as well as a drive mechanism 11 for driving crystal growth. The drive mechanism, mounted above the top cover 8, includes a seed crystal chuck and a lifting and rotating mechanism for holding the seed crystal and rotating and slowly lifting it during crystal growth to control the crystal's shape and quality. An oxygen-containing growth atmosphere, which can be dry air or a mixture of oxygen and inert gas, is introduced into the second chamber through a second air inlet 9 located at the bottom of the substrate to maintain the required oxygen partial pressure. Similarly, a second air outlet 10 is provided to exhaust gas from the second chamber, cooperating with the second air inlet to control the gas flow and pressure within the chamber.

[0076] To achieve precise control of the oxygen partial pressure during crystal growth, the second chamber is equipped with an independent dual-channel gas control unit, which includes a multi-gas source module and a gas monitoring module. The multi-gas source module contains an inert gas source and an oxygen source, and the gas flow rate is controlled by a dual-channel flow controller with a flow rate adjustment range of 10-50 L / h. The pressure detection module includes a pressure sensor located inside the second chamber for real-time monitoring of the total pressure and oxygen partial pressure within the second chamber. Similarly, the first atmosphere management unit includes a pressure detection module for real-time monitoring of the pressure within the first chamber.

[0077] See Figure 2 In this embodiment, the combined crucible 14 includes a crucible 101 with a first inner diameter and a crucible support 100 with a second inner diameter. The crucible 101 is made of a chemically resistant material, such as platinum, platinum-rhodium alloy, platinum-iridium alloy, magnesium oxide, zirconium oxide, etc., with a wall thickness of 0.1-0.8 mm. It is used for heating and / or holding molten material at high temperatures and is detachably supported on the crucible support 100, which provides mechanical strength. The crucible support 100 is made of a heat-resistant material, with a bottom thickness approximately 2 to 3 times the sidewall thickness, and a second inner diameter approximately 30 to 50 times the sidewall thickness. The crucible 101 and the crucible support 100 are arranged coaxially, with the second inner diameter being 1-3 cm larger than the first inner diameter, thereby forming an annular gap between the outer wall of the crucible 101 and the inner wall of the crucible support 100.

[0078] In one specific embodiment, the crucible 101 is made of a material selected from platinum, platinum-rhodium alloy, or platinum-iridium alloy, with a wall thickness of 0.3 mm and an inner diameter of 6 cm. When made of platinum-rhodium alloy, the rhodium content is greater than or equal to 10 wt%. When made of platinum-iridium alloy, the iridium content is greater than or equal to 15 wt%. The crucible support 100 is made of high-temperature resistant alumina, magnesium oxide, or zirconium oxide, with a wall thickness of 2 mm, a bottom thickness of 4 mm, and an inner diameter of 8 cm. The crucible 101 is placed on the high-strength crucible support 100, forming a gap of approximately 5 mm between them.

[0079] In another specific embodiment, the crucible can also be made of high-temperature resistant magnesium oxide or zirconium oxide, further reducing production costs.

[0080] In another specific embodiment, the crucible is made of iridium composite material, which is prepared by forming a dense zirconium monoxide layer on a 0.4 mm thick iridium surface using a plasma spraying process. The thickness of the dense zirconium monoxide layer is approximately 100-200 μm. This reduces both the loss of iridium due to oxidation during crystal growth and the amount of iridium used, thus significantly reducing production costs.

[0081] The shapes and dimensions of the sealing cap 7 for sealing the first chamber and the upper cover 8 for sealing the second chamber form a tight mechanical fit. The annular sealing cap 7 has a third inner diameter and a fourth inner diameter smaller than the third inner diameter, forming a concave shape. The upper cover 8 has a first diameter and a second diameter that mechanically fit with the annular sealing cap 7, wherein the first diameter is larger than the second diameter, forming a convex shape.

[0082] In one specific embodiment, the annular sealing cap 7 is made of a high-temperature resistant ceramic material, such as magnesium oxide, aluminum oxide, or zirconium oxide, and the top cover 8 is made of alumina hollow spheres or zirconium oxide fiber bricks.

[0083] An observation window 12 is provided on the side wall of the furnace lining. It is usually made of a high-temperature resistant transparent material such as quartz glass or sapphire, so that the operator can observe the melt and crystal growth inside the furnace.

[0084] The apparatus for growing gallium oxide single crystals also includes an integrated temperature monitoring system, which comprises an infrared thermometer 13 and a high-resolution infrared camera. The infrared thermometer 13 measures the temperature of the crucible 101 or the surface of the melt non-contactly through an observation window 12 and the atmosphere separation and heat conduction components 6, and feeds the measured temperature signal back to the central control system to adjust the heater power, thereby achieving precise control of the crystal growth temperature. The high-resolution infrared camera is used to acquire real-time images of the temperature distribution on the melt surface and at the solid-liquid interface.

[0085] In another embodiment of the invention, the integrated temperature monitoring system further includes a thermocouple, which serves as a temperature sensor and is disposed within the first chamber. The measuring end of the thermocouple is in close contact with the outer wall of the atmosphere separation and heat conduction component. This arrangement forms a dual independent temperature control system within the entire single crystal growth equipment, with the first and second chambers controlling the temperature within their respective areas. This helps extend the lifespan of the heater while ensuring the growth environment and quality level of the single crystal.

[0086] The gallium oxide single crystal growth equipment also includes a central control system, which comprises temperature sensors, pressure sensors, oxygen partial pressure sensors, and a central processing unit. Furthermore, the central control system is electrically connected and communicates with the protective heating system, the drive mechanism of the crystal growth system, the atmosphere control system, and the integrated temperature detection system. The central control system incorporates a differential pressure control algorithm, which, based on collected data, adjusts in real time the heating power of the protective heating system, the displacement and rotation speed of the drive mechanism of the crystal growth system, the gas flow and pressure of the atmosphere control system, and the temperature within the chamber. This ensures that at any point during the entire crystal growth process, the gas pressure in the first chamber is consistently and precisely maintained at a preset small positive pressure value ΔP higher than the gas pressure in the second chamber. This preset value ΔP is typically set to a range of 1 kPa to 10 kPa, or even 1 kPa to 5 kPa. This active differential pressure control strategy significantly improves process safety, prevents oxygen-containing atmosphere from flowing from the second chamber to the first chamber, and extends the lifespan of the heater.

[0087] Example 2

[0088] See Figure 3 and Figure 4 This illustrates yet another specific embodiment of the present application. Compared to Embodiment 1, in this embodiment, the manufacturing equipment for growing gallium oxide single crystals has been further improved in terms of heating elements and combined crucibles.

[0089] The heating element 3 comprises at least three arrays 310 of heating elements that are independently controlled along the vertical direction. This multi-temperature zone design allows for the establishment and precise control of the required temperature gradient in the axial direction, which is crucial for different stages of crystal growth, such as melting, crystal growth, and constant-diameter growth. Each array of heating elements 310 consists of a plurality of heating elements.

[0090] In this embodiment, heating element 3 is a honeycomb graphite heater. Honeycomb graphite, due to its honeycomb channel structure, possesses high specific surface area, high structural flexibility, and low density. Therefore, compared to solid graphite, the heating area is increased by 2-3 times, the heating temperature is more uniform, and the hot spot temperature difference can be controlled within <5℃. Because the infrared radiation path is reflected multiple times by the pore walls, the radiation efficiency is >85%, and the heating time is shortened by 20-30%. The honeycomb pores can better release thermal stress, reducing the probability of thermal shock cracks by 40%, and the deformation after 2000 hours of continuous operation is <0.2mm. Simultaneously, honeycomb graphite is 30-40% lighter than a solid graphite heater of the same power, reducing the support structure and inertial load, which is beneficial for rapid furnace lifting and lowering. Actual operation data shows that after replacing the 4-inch β-Ga2O3 Czochralski furnace with a honeycomb graphite heater, the heater lifespan increased from 12 months to 18 months, and the heating time was shortened from 3.5 hours to 2.4 hours.

[0091] like Figure 4 As shown, the combined crucible 14 includes a crucible 101 with a first inner diameter and a crucible support 100 with a second inner diameter. The crucible 101 is made of a platinum-rhodium alloy, wherein the rhodium content is greater than or equal to 10 wt%. The crucible wall is 0.5 mm thick and has an inner diameter of 8 cm. It is used for heating and / or holding the molten material at high temperatures and is detachably supported on the crucible support 100, which provides mechanical strength. The bottom of the crucible 101 has an arc-shaped transition, and the sidewalls are slightly tapered, resulting in a bottom radius of curvature ratio of approximately 1:3 to the first inner diameter of the crucible, avoiding dead zones for melt convection. The sidewalls form a 0.5°-1° micro-taper from bottom to top, reducing interfacial stress during crystal growth.

[0092] The crucible support 100 is made of alumina, with a wall thickness of 2mm, a bottom thickness of 5mm, and an inner diameter of 10cm. The purpose of thickening the bottom of the crucible support 100 is to further enhance its support and improve its resistance to deformation.

[0093] The crucible 101 and the crucible support 100 are arranged coaxially, and the second inner diameter is 2 cm larger than the first inner diameter, thus forming an annular gap between the outer wall of the crucible 101 and the inner wall of the crucible support 100.

[0094] To address the uneven thermal resistance between the inner crucible and the outer crucible support, ensuring uniform heat transfer from the heating element to the melt and preventing gallium oxide decomposition due to localized overheating, thus avoiding the formation of metallic gallium, and simultaneously reducing temperature fluctuations at the solid-liquid interface by controlling the interface temperature within ±1℃, a coaxially arranged thermally conductive layer 15 is disposed within the annular gap. This thermally conductive layer can be selected from silicon carbide nanowire arrays and / or alumina nanospheres. The silicon carbide nanowire array / alumina nanospheres exhibit excellent thermal conductivity, forming a "micropillar support-thermal bridge" structure between the outer wall of the crucible 101 and the inner wall of the crucible support 100, enhancing radial heat conduction.

[0095] Due to the difference in thermal expansion coefficients between the crucible 101 and the crucible support 100, stress is easily generated at high temperatures. To prevent the crucible 101 from cracking or the support 100 from deforming, and to compensate for the slight shrinkage of the crucible after long-term use, such as the radial pressure exerted on the crucible when gallium oxide melt solidifies, this embodiment also provides a pressure compensation layer 16, which is made of nickel-titanium shape memory alloy fiber felt. The porosity of the fiber felt is about 60%-70%, and the diameter of the alloy fibers is 50-100μm. Nickel-titanium shape memory alloy has stable superelasticity below 1800℃, with an elastic deformation of up to 8%, and its oxidation resistance at high temperatures is superior to that of traditional metal materials.

[0096] Nickel-titanium shape memory alloy fiber felt is cut into rings with a thickness of 0.5-1mm and wrapped around the outside of the heat-conducting layer, making direct contact with the inner wall of the crucible support 101. When the temperature rises, the fiber felt generates radial thrust due to thermal expansion, which counteracts the expansion difference between the crucible and the support; when the temperature drops or the crucible contracts, the fiber felt elastically rebounds, maintaining stable contact pressure.

[0097] In addition, 5%-10% cerium oxide nanoparticles can be doped into the fiber felt to further buffer pressure fluctuations caused by melt convection, utilizing their high-temperature plastic flow properties. Depending on the actual filling situation, multiple thermally conductive layers and pressure compensation layers can be alternately and repeatedly set within the annular voids.

[0098] The modular crucible design in this embodiment achieves higher thermal uniformity, reducing the radial temperature difference of the melt from 15-20°C in traditional designs to below 5°C, and improving the solid-liquid interface smoothness by 40%. Furthermore, stress damage is significantly reduced; after 100 heating and cooling cycles, the crucible shows no cracks, and the support deformation is <0.1mm. The dislocation density of gallium oxide single crystals manufactured using this equipment is reduced from 102... 5 / cm 2 Reduced to 10 4 / cm 2 The following significantly improves the growth quality and stability of gallium oxide single crystals.

[0099] Example 3

[0100] use Figure 1 and Figure 2 The growth apparatus shown is used to grow low-defect-density gallium oxide single crystals. A cylindrical atmosphere separation and heat conduction assembly made of zirconia transparent ceramic is used. This cylindrical assembly, together with its top cover, forms a second chamber to house the combined crucible and the melt. The cylindrical assembly, the furnace lining, and the annular sealing cover mounted on top of both constitute the first chamber, which is a concentric annular space surrounding the exterior of the second chamber. Thus, this assembly divides the furnace cavity into two mutually isolated, airtight chambers. Both the first and second chambers are equipped with independent temperature monitoring and control systems and gas management systems. The combined crucible support is made of magnesia ceramic, and the crucible is a platinum-rhodium alloy (15 wt% rhodium content). Graphite is used as the heating element in the heater.

[0101] The process flow for gallium oxide single crystal growth is as follows:

[0102] Sintered gallium oxide ingots with a purity of 99.999% were loaded into a combined crucible, filling the crucible to 80% of its volume. The crucible was placed in the center of the second chamber, and the top cover was placed on the annular sealing cover. After sealing the furnace, a vacuum of 1×10⁻⁶ was evacuated. - 3Pa. High-purity argon gas (99.999% purity) is introduced into the first chamber, and dry air (with an oxygen partial pressure of 19%) is introduced into the second chamber. The pressure is brought to the set point and stabilized for 30 minutes. The argon gas flow rate is 20 L / h, the predetermined pressure is 0.12 MPa, the air flow rate is 15 L / h, the predetermined pressure is 0.11 MPa, and the pressure difference between the first and second chambers is maintained at 0.01 MPa.

[0103] The graphite heater was heated by an induction coil to 1805℃ and held for 3 hours to completely melt the raw material. A β-Ga2O3 seed crystal (crystal orientation

[010] ) was lowered to the surface of the melt and pulled at a rotation speed of 3 r / min and a pulling speed of 0.5 mm / h, necking the crystal to a diameter of 2 mm and a length of 10 mm. During this process, the flow rate of the dry air was reduced to 9-10 L / h, and the high-purity argon gas channel of the second chamber was opened, allowing argon gas to be introduced at a flow rate of 5-6 L / h to stabilize the oxygen partial pressure at 9-10%.

[0104] The rotation speed was then adjusted to 6 r / min, and the lifting speed to 1 mm / h for constant diameter growth. The flow rate of dry air was increased to 10-12 L / h, and the flow rate of high-purity argon was increased to 8-10 L / h to stabilize the oxygen partial pressure at 10%-15%. Meanwhile, the pressure in the second chamber was maintained at 0.11 MPa.

[0105] Finally, the process was completed with a rotation speed of 3 r / min and a pulling speed of 2.0 mm / h. When the crystal completed the final stage, the single crystal end formed a cone shape, detached from the melt, and cooled in the furnace at a cooling rate of 50℃ / h. During this process, the flow rate of dry air was further reduced, while the flow rate of high-purity argon was increased to stabilize the oxygen partial pressure below 10%. Simultaneously, the pressure in the second chamber was maintained at 0.11 MPa.

[0106] Thirty minutes after the cooling program in the second chamber is initiated, the cooling of the first chamber is started. The cooling rate of the first chamber can be equal to or lower than that of the second chamber. The temperature of the second chamber is monitored in real time using thermocouples, and the temperature of the first chamber is monitored in real time using an infrared thermometer to ensure that the temperature difference between the two chambers is always controlled within 20°C.

[0107] When the temperature drops to 1200℃, the dry air channel is closed, and the second chamber is switched to argon gas, with the argon pressure maintained at 0.11MPa. When the temperature in the first chamber drops to 800℃, the argon flow rate in the first chamber is gradually reduced to minimize inert gas loss. Inert gas supply can be completely stopped when the temperature difference between the first chamber and the external environment is less than 200℃, and the pressure sensor confirms that the pressure in the first chamber is consistent with the external atmospheric pressure, preventing backflow of external air due to thermal convection. After the second chamber cools to room temperature, the crystal is removed, yielding a crack-free, transparent gallium oxide single crystal with a minimum defect density of <5×10⁻⁶. 3 cm -2 .

[0108] In this embodiment, a groundbreaking combined crucible significantly reduces iridium consumption, while a low-cost graphite heater completely replaces traditional expensive precious metal heating elements, significantly lowering production costs. Through an innovative cavity partitioning design, the first chamber employs a high-purity inert atmosphere to effectively protect the heater and enhance equipment safety. The second chamber uses a high-oxygen partial pressure atmosphere, enabling precise control of the crystal growth environment, reducing the risk of melt decomposition, and effectively suppressing instability factors during crystal growth. Furthermore, relying on advanced dual-path atmosphere control technology, independent dual-chamber temperature control technology, and differential pressure control technology, this invention can precisely adjust the atmospheric composition and distribution in the growth environment, effectively reducing oxygen vacancy defects in the crystal, improving crystal integrity and purity, and synergistically addressing temperature and pressure changes in both the first and second chambers, achieving a significant breakthrough in crystal defect control. Compared to the difficulty in effectively controlling defects in existing technologies, this invention provides strong technical support for obtaining high-quality, low-defect gallium oxide single crystals.

[0109] Example 4

[0110] use Figure 3 and Figure 4The growth apparatus shown is used to grow low-defect-density gallium oxide single crystals. A cylindrical atmosphere separation and heat conduction assembly, made of magnesium aluminum spinel transparent ceramic, is used. This cylindrical assembly and its top cover together form a second chamber for housing the combined crucible and melt. The cylindrical assembly, the furnace lining, and the annular sealing cover mounted on top of both constitute the first chamber, which is a concentric annular space surrounding the exterior of the second chamber. Thus, this assembly divides the furnace cavity into two mutually isolated, airtight chambers. Both the first and second chambers are equipped with independent temperature monitoring and control systems and gas management systems. Honeycomb graphite is used as the heating element for the heater. The combined crucible support is made of zirconia ceramic, and the crucible is a platinum-iridium alloy (iridium content 20% wt). A coaxially arranged thermally conductive layer and an adaptive pressure compensation layer are arranged within the annular gap. The thermally conductive layer is a silicon carbide nanowire array, forming a "micropillar support-thermal bridge" structure between the outer wall of the crucible and the inner wall of the crucible support, enhancing radial heat conduction. The pressure compensation layer is a ring-shaped layer with a thickness of 0.5-1 mm, wrapped around the outside of the thermally conductive layer, and in direct contact with the inner wall of the crucible support. The pressure compensation layer is made of nickel-titanium shape memory alloy fiber felt doped with 5%-10% cerium oxide nanoparticles, with a filament diameter of 50-100 μm and a porosity of approximately 60%-70%. In this embodiment, additional thermally conductive layers and adaptive pressure compensation layers may be assumed as needed.

[0111] The process flow for gallium oxide single crystal growth is as follows:

[0112] Sintered gallium oxide ingots with a purity of 99.999% were loaded into a combined crucible, filling the crucible to 80% of its volume. The crucible was placed in the center of the second chamber, and the top cover was placed on the annular sealing cover. After sealing the furnace, a vacuum of 2 × 10⁻⁶ was evacuated. - 3 Pa. High-purity argon gas (99.999% purity) is introduced into the first chamber, and a mixture of argon and oxygen gas (with an oxygen partial pressure of 20%) is introduced into the second chamber. The mixture is introduced until the set pressure is reached and stabilized for 40 minutes. The argon gas flow rate is 25 L / h, the predetermined pressure is 0.13 MPa, the mixed gas flow rate is 20 L / h (argon flow rate is 15 L / h, oxygen flow rate is 5 L / h), and the predetermined pressure is 0.12 MPa. The pressure difference between the first and second chambers is maintained at 0.01 MPa.

[0113] The graphite heaters are heated by induction coils. The graphite heaters located at the top of the furnace lining have lower output power, while those located in the middle and lower parts of the furnace lining have higher output power. This arrangement aims to create multiple temperature fields within the second chamber. The temperature above the melt is lower, which is conducive to crystal growth. The temperature in the melt region rises to 1810℃ more quickly and is held for 2 hours to completely melt the raw materials. The β-Ga2O3 seed crystal (crystal orientation

[010] ) is lowered to the surface of the melt and pulled at a rotation speed of 5r / min and a pulling speed of 0.6mm / h, necking the crystal to a diameter of 2mm and a length of 15mm. During this process, the oxygen flow rate is gradually reduced to 1-3L / h, the argon flow rate is increased to 17-19L / h, and the oxygen partial pressure is stabilized at 1%-10%.

[0114] The rotation speed was then adjusted to 8 r / min, and the lifting speed to 1.2 mm / h for constant diameter growth. The oxygen flow rate was increased to 3-4 L / h, and the argon flow rate was decreased to 16-18 L / h, stabilizing the oxygen partial pressure at 10%-15%. Simultaneously, the pressure in the second chamber remained at 0.12 MPa.

[0115] Finally, the process was completed with a rotation speed of 5 r / min and a pulling speed of 2.0 mm / h. When the crystal completed the final stage, the single crystal end formed a cone shape, detached from the melt, and cooled in the furnace at a cooling rate of 40℃ / h. During this process, the flow rate of dry oxygen was further reduced, while the flow rate of high-purity argon was increased to stabilize the oxygen partial pressure below 10%. Simultaneously, the pressure in the second chamber was maintained at 0.12 MPa.

[0116] Thirty minutes after the cooling program in the second chamber is initiated, the cooling of the first chamber is started. The cooling rate of the first chamber can be equal to or lower than that of the second chamber. The temperature of the second chamber is monitored in real time using thermocouples, and the temperature of the first chamber is monitored in real time using an infrared thermometer to ensure that the temperature difference between the two chambers is always controlled within 20°C.

[0117] When the temperature drops to 1150℃, the oxygen channel is closed, and the second chamber is switched to argon gas, with the argon pressure maintained at 0.12MPa. When the temperature in the first chamber drops to 800℃, the argon flow rate in the first chamber is gradually reduced to minimize inert gas loss. Inert gas supply can be completely stopped when the temperature difference between the first chamber and the external environment is less than 200℃, and the pressure sensor confirms that the pressure in the first chamber is consistent with the external atmospheric pressure, preventing backflow of external air due to thermal convection. After the second chamber cools to room temperature, the crystal is removed, yielding a crack-free, transparent gallium oxide single crystal with a minimum defect density of <5×10⁻⁶. 3 cm -2 .

[0118] Example 5

[0119] use Figure 1 and Figure 2 The growth apparatus shown is used to grow low-defect-density gallium oxide single crystals. A cylindrical atmosphere separation and heat conduction assembly made of zirconia transparent ceramic is used. This cylindrical assembly, together with its top cover, forms a second chamber to house the combined crucible and the melt. The cylindrical assembly, the furnace lining, and the annular sealing cover mounted on top of both constitute the first chamber, which is a concentric annular space surrounding the second chamber. Thus, this assembly divides the furnace cavity into two mutually isolated, gas-tight chambers. Both the first and second chambers are equipped with independent temperature monitoring and control systems and gas management systems. The combined crucible support is made of magnesium oxide ceramic, and the crucible is a platinum crucible with a wall thickness of 0.15 mm. A dense zirconia coating, 150 μm thick, is applied to the inner wall of the crucible using plasma deposition. Graphite is used as the heating element in the heater.

[0120] The process flow for gallium oxide single crystal growth is as follows:

[0121] Sintered gallium oxide ingots with a purity of 99.999% were loaded into a combined crucible, filling the crucible to 80% of its volume. The crucible was placed in the center of the second chamber, and the top cover was placed on the annular sealing cover. After sealing the furnace, a vacuum of 3 × 10⁻⁶ was evacuated. - 4 Pa. Prepare an iridium or molybdenum alloy mold. Introduce high-purity argon (99.999% purity) into the first chamber and dry air (oxygen partial pressure 19%) into the second chamber until the set pressure is reached and stabilized for 30 minutes. The argon flow rate is 20 L / h at a predetermined pressure of 0.12 MPa, and the air flow rate is 15 L / h at a predetermined pressure of 0.11 MPa. Maintain a pressure difference of 0.01 MPa between the first and second chambers.

[0122] The graphite heater is heated by an induction coil to 1800℃ and held for 3 hours to completely melt the raw material. A β-Ga2O3 seed crystal (crystal orientation

[010] ) is lowered to the surface of the melt and pulled at a rotation speed of 6 r / min and a pulling speed of 0.8 mm / h, necking the crystal to a diameter of 2 mm and a length of 10 mm. During this process, the flow rate of the dry air is reduced to 7-9 L / h, and the high-purity argon gas channel of the second chamber is opened, allowing argon gas to be introduced at a flow rate of 6-8 L / h to stabilize the oxygen partial pressure at 5-8%.

[0123] The rotation speed was then adjusted to 7-10 r / min, and the lifting speed to 3-8 mm / h for constant diameter growth. The flow rate of dry air was increased to 10-12 L / h, while the flow rate of high-purity argon was reduced to 4-6 L / h to stabilize the oxygen partial pressure at 10%-15%. Simultaneously, the pressure in the second chamber remained at 0.11 MPa.

[0124] Finally, the pulling speed is reduced to 10-15 mm / h. After the crystal completes the final stage, the single crystal is removed from the melt and cooled in the furnace at a rate of 50℃ / h. During this process, the flow rate of dry air is further reduced and the flow rate of high-purity argon is increased to stabilize the oxygen partial pressure below 10%, while the pressure in the second chamber is maintained at 0.11 MPa.

[0125] Thirty minutes after the cooling program in the second chamber is initiated, the cooling of the first chamber is started. The cooling rate of the first chamber can be equal to or lower than that of the second chamber. The temperature of the second chamber is monitored in real time using thermocouples, and the temperature of the first chamber is monitored in real time using an infrared thermometer to ensure that the temperature difference between the two chambers is always controlled within 20°C.

[0126] When the temperature drops to 1200℃, the dry air channel is closed, and the second chamber is switched to argon gas, with the argon pressure maintained at 0.11MPa. When the temperature in the first chamber drops to 800℃, the argon flow rate in the first chamber is gradually reduced to minimize inert gas loss. Inert gas supply can be completely stopped when the temperature difference between the first chamber and the external environment is less than 200℃, and the pressure sensor confirms that the pressure in the first chamber is consistent with the external atmospheric pressure, preventing backflow of external air due to thermal convection. After the second chamber cools to room temperature, the crystal is removed, yielding a crack-free, transparent gallium oxide single crystal with a minimum defect density of <5×10⁻⁶. 3 cm -2 .

[0127] Comparative Example 1

[0128] Similar to Example 3, but with the difference of using a traditional single-cavity structure, the atmosphere is controlled solely by introducing a mixture of carbon dioxide and argon, with an oxygen partial pressure of 4%. A thick-walled iridium crucible (2 mm thick) and an iridium wire heater are used. Gallium beads (decomposition products) appear on the melt surface during growth, and impurities adhere to the crystal surface during crystal pulling. The resulting gallium oxide crystal after growth contains bubbles, with an oxygen vacancy defect density ≥ 1.5 × 10⁻⁶. 9 cm -3 Furthermore, the iridium crucible exhibited significant oxidation and corrosion.

[0129] Comparative Example 2

[0130] Similar to Example 4, but with the difference of using a traditional single-cavity structure and a graphite heater as the heating element. A thick-walled iridium crucible with a wall thickness of 2 mm is used.

[0131] After the vacuuming is completed, the furnace cavity is filled with the same atmosphere as the second chamber in Example 4, that is, a mixed gas with a pressure of 0.12 MPa and a composition of 20% oxygen and 80% argon, with a flow rate of 20 L / h, of which the argon flow rate is 15 L / h and the oxygen flow rate is 5 L / h.

[0132] During growth, graphite undergoes trace volatilization or oxidation at high temperatures to generate CO / CO, which dissolves in the melt, leading to carbon incorporation into the gallium oxide single crystal. Simultaneously, graphite oxidation causes localized thinning and cracking, resulting in carbon contamination within the second chamber. After growth, the resulting gallium oxide crystal exhibits carbon doping and microcracks, with the dislocation density increasing to >102. 5 cm -2 Furthermore, under the high oxygen partial pressure of this comparative example, the oxidation rate of the graphite heater increases sharply, and its lifespan is shortened to only 100-200 hours.

[0133] It should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and are not intended to limit it. Although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this disclosure without departing from the spirit and scope of the technical solutions of this disclosure, and all such modifications and substitutions should be covered within the scope of the claims of this disclosure.

Claims

1. A growth apparatus for low-defect single crystals, said apparatus being used for growing low-defect gallium oxide single crystals by the Czochralski method or the mode-guided method, characterized in that, include: A furnace body, wherein a cylindrical atmosphere separation and heat conduction assembly is provided inside the furnace body, the atmosphere separation and heat conduction assembly physically divides the internal space of the furnace body into a first chamber and a second chamber that are isolated from each other and arranged coaxially. A protective heating system, the heating system including a heating element disposed in the first chamber, the surface of the heating element being provided with a protective coating; An atmosphere control system includes a first atmosphere management unit connected to a first chamber for supplying and maintaining a protective atmosphere to the first chamber; and a second atmosphere management unit connected to a second chamber for supplying and maintaining an oxygen-containing atmosphere to the second chamber. A temperature control system includes a first temperature management unit connected to a first chamber for regulating the temperature of the first chamber; and a second temperature management unit connected to a second chamber for regulating the temperature of the second chamber. A central control system, comprising a temperature sensor, a pressure sensor, an oxygen partial pressure sensor, and a central processing unit; and A crystal growth system includes a combined crucible disposed in a second chamber. The combined crucible includes a crucible with a first inner diameter and a crucible support with a second inner diameter. The wall thickness of the crucible is 0.1-0.8 mm. The crucible and the crucible support are coaxially arranged. The second inner diameter is 1-3 mm larger than the first inner diameter, thereby forming an annular gap between the outer wall of the crucible and the inner wall of the crucible support. An adaptive pressure compensation layer is disposed coaxially within the annular gap. The adaptive pressure compensation layer is selected from nickel-titanium shape memory alloy fiber felt or ceramic fiber.

2. The low-defect single crystal growth apparatus according to claim 1, characterized in that, The atmosphere separation and heat conduction component is integrally formed from high-temperature resistant transparent ceramic with a wall thickness of 5 mm to 15 mm. The high-temperature resistant transparent ceramic is selected from zirconia transparent ceramic, magnesium aluminum spinel transparent ceramic, or sapphire.

3. The low-defect single crystal growth apparatus according to claim 1, characterized in that, The heating element body is selected from graphite, honeycomb graphite, molybdenum disilicide or tungsten alloy, and the protective coating includes at least one layer; the heating element includes at least one set.

4. The low-defect single crystal growth apparatus according to claim 1, characterized in that, The crucible, made of an oxidation-resistant material with a wall thickness of 0.1-0.8 mm, is used for heating and / or holding the melt at high temperatures and is detachably supported on the crucible support. The oxidation-resistant material includes iridium, platinum, platinum-iridium, platinum-rhodium, composite iridium, aluminum oxide, magnesium oxide, and zirconium oxide. The crucible support is made of a heat-resistant material with a bottom thickness of 2 to 3 times the sidewall thickness and a second inner diameter of 30 to 50 times the sidewall thickness. The heat-resistant material includes magnesium oxide, aluminum oxide, or zirconium oxide. The adaptive pressure compensation layer may contain cerium oxide nanoparticles.

5. The low-defect single crystal growth apparatus according to claim 1, characterized in that, The first atmosphere management unit includes a first air pressure detection module for real-time monitoring of the pressure inside the first chamber; The second atmosphere management unit includes a multi-gas source module and a pressure detection module; the multi-gas source module includes an inert gas source and an oxygen-containing gas source; the pressure detection module includes a pressure sensor installed inside the second chamber for real-time monitoring of the pressure and oxygen partial pressure inside the second chamber.

6. The low-defect single crystal growth apparatus according to claim 1, characterized in that, Also includes: An integrated temperature monitoring system includes: an infrared thermometer that measures the temperature inside the crucible in the crystal growth system non-contactly through an optical window set on the furnace body; An infrared thermal imaging feedback unit, including a high-resolution infrared camera, is set outside the observation window on the side wall of the furnace body. Through the atmosphere separation and heat conduction components, it acquires real-time images of the temperature distribution on the surface of the melt and the solid-liquid interface.

7. The low-defect single crystal growth apparatus according to claim 6, characterized in that, The integrated temperature monitoring system also includes a thermocouple, which is installed on the atmosphere separation and heat conduction component in the first chamber for real-time monitoring of the temperature in the first chamber.

8. The low-defect single crystal growth apparatus according to claim 1, characterized in that, The central control system is electrically connected and communicates with the protective heating system, the drive mechanism of the crystal growth system, the atmosphere control system, and the integrated temperature detection system. The central control system has a built-in differential pressure control algorithm, which adjusts the heating power of the protective heating system, the displacement speed of the drive mechanism of the crystal growth system, the gas flow rate and oxygen partial pressure of the atmosphere control system, and the furnace temperature in real time based on the collected data.

9. A method for growing low-defect gallium oxide single crystals based on the apparatus described in claims 1-8, characterized in that, Includes the following steps: S1. Loading: Load the high-purity gallium oxide raw material into the crucible and place it in the center of the second chamber; S2. Chamber atmosphere initialization: Inert gas is introduced into the first chamber to atmospheric pressure or slightly positive pressure, and oxygen-containing gas is introduced into the second chamber to make the oxygen partial pressure reach the preset value; the pressure difference between the first chamber and the second chamber is kept below the preset threshold. S3. Melt preparation: Start the protective heating system, raise the temperature through the heating element and maintain it for a certain time to completely melt the gallium oxide raw material; S4. Crystal Growth: In this step, dynamic atmosphere adjustment is performed. Based on feedback from the temperature monitoring system and the gas pressure detection module, the oxygen ratio in the oxygen-containing gas is adjusted in real time. During the crystal introduction stage, the crystal grows at the first temperature, maintaining the oxygen volume ratio at 0-10%. During the crystal growth stage, the crystal grows at the second temperature, maintaining the oxygen volume ratio at 15-25%. After the crystal growth is completed, the temperature is gradually lowered to the third temperature, gradually reducing the oxygen volume ratio from 10% to 0. S5. Cooling and depressurization control of the first chamber: After the second chamber starts cooling for a certain period of time, the first chamber begins to cool down at a rate equal to or lower than that of the second chamber, and the temperature difference between the first and second chambers is kept within 30°C; when the temperature in the first chamber approaches the oxidation critical temperature of the heating element, the inert gas flow rate is gradually reduced; when the temperature difference between the first chamber and the outside air temperature is below 200°C and the pressure in the first chamber is equal to the outside air pressure, the inert gas is shut off. S6. Crystal Removal: After the crystal has cooled to room temperature, remove the crystal.

10. The growth method according to claim 9, characterized in that: In step S2, the pressure difference between the first chamber and the second chamber is maintained below 10 kPa; In step S4, the second temperature is equal to or lower than the first temperature, and the third temperature is lower than the second temperature; In step S4, when the apparatus is used to grow gallium oxide single crystals by the Czochralski method, the product of the pulling speed and the rotation speed of the driving mechanism of the crystal growth system is in the range of 1-10 mm·rpm / h. During the crystal growth process in steps S3 to S5, the solid-liquid interface temperature distribution is monitored in real time using an infrared thermal imaging feedback unit. The central control system optimizes the oxygen-argon ratio and heating power based on temperature, partial pressure changes, and pulling speed parameters, so that the axial temperature gradient inside the furnace is stabilized at 5-8℃ / cm and the radial temperature gradient is stabilized within 1-5℃.

11. The growth method according to claim 10, characterized in that: In step S2, the pressure difference between the first chamber and the second chamber is kept below 5 kPa.

12. The gallium oxide single crystal obtained by the growth method according to claims 9-11, characterized in that: Gallium oxide single crystals are crack-free, transparent, and have the lowest crystal defect density (<5×10⁻⁶). 3 cm -2 .

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