Cosolvent for beta-Ga2O3 crystal growth, application of cosolvent and crystal growth method

Abstract

The invention discloses a cosolvent for beta-Ga2O3 crystal growth, application of the cosolvent and a crystal growth method, the cosolvent for beta-Ga2O3 crystal growth comprises a mixture composed of bismuth oxide and boron oxide, and the molar ratio range of bismuth oxide to boron oxide is (0.5-2): (2-5). When the cosolvent is used for crystal growth of beta-Ga2O3, the melting temperature can be reduced to 1200 DEG C or below, and the purpose of low carbon is achieved; melting can be carried out in an air atmosphere; the method can be suitable for a relatively high heating rate of 50 DEG C / h to 200 DEG C / h, a relatively short heat preservation time of 3 h to 8 h and a relatively high cooling rate of 5 DEG C / h to 10 DEG C / h, so that the purposes of high efficiency and stability are achieved; and moreover, the cosolvent does not contain toxic auxiliaries such as lead oxide or fluoride, so that the influence on the health of an operator and the environment can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of crystal growth, in particular to a cosolvent for β-Ga2O3 crystal growth, application thereof and a crystal growth method. BACKGROUND

[0002] The fourth generation semiconductor material gallium oxide (Ga2O3) has significant application value in the fields of ultra-high voltage power devices, deep ultraviolet photodetection and energy-saving power electronics due to its advantages of super-wide band gap width, super-high breakdown field strength and super-large Baliga quality factor.

[0003] In the preparation of β-Ga2O3 crystal, although the melt single crystal growth technology can greatly reduce the production cost, due to the high melting point of β-Ga2O3 of 1820℃, the commonly used crystal growth methods such as Czochralski method and edge-defined film-fed growth method need to be carried out in a high-temperature environment containing oxygen. This makes the crucible material must use the noble metal iridium gold which is resistant to high temperature and corrosion. In addition, in the process of crystal growth, problems such as decomposition and volatilization of high-temperature raw materials, corrosion of iridium gold crucible and the like are prone to occur.

[0004] In order to solve a series of problems caused by the high preparation temperature of β-Ga2O3, people thought of adding specific chemicals to the β-Ga2O3 raw material to form a eutectic mixture, thereby significantly reducing the melting point of the system. This method is called flux method or molten salt method, which can reduce the high temperature requirement, reduce energy consumption, and avoid decomposition, volatilization and other problems of materials due to high temperature. However, the flux method in the prior art more or less has some problems: for example, the β-Ga2O3 crystal growth method using TeO2 and alkali carbonate as flux disclosed in the Chinese patent application for invention with publication number CN118516740A has the problems of slow heating rate, long holding time, and slow cooling rate; the β-Ga2O3 crystal growth method using bismuth oxide-alkali metal fluoride system as flux disclosed in the Chinese patent for invention with publication number CN114214720B not only has the problem of long holding time, but also has the problem of harming the health of operators and the environment due to the toxicity of alkali metal fluoride; the β-Ga2O3 crystal growth method using boron source, alkali metal source and molybdenum-containing compound as flux disclosed in the Chinese patent for invention with publication number CN114250514B has the problems of long holding time and slow cooling rate; the β-Ga2O3 crystal growth method using alkaline earth metal nitride as flux disclosed in the Chinese patent for invention with publication number CN100425743C has the problems of needing to be in a vacuum environment and holding for a long time; the β-Ga2O3 crystal growth method using boron trioxide or tin dioxide as flux disclosed in the Chinese patent application for invention with publication number CN117328132A still has the problems of high growth temperature (as high as 1500°C or more), long holding time and slow cooling rate; the β-Ga2O3 crystal growth method using vanadium pentoxide or a mixture composed of vanadium pentoxide and boron oxide as flux disclosed in CN119800486A still has the problem of long holding time.

[0005] Therefore, it is of great significance to construct an efficient, stable, healthy, low-carbon and environmentally friendly flux system for the large-size and low-defect growth of β-Ga2O3 crystals, and it is a key research direction in this field. SUMMARY

[0006] In order to solve at least one of the foregoing problems, the inventors have conducted a large number of researches and experiments, and in the process of research and experiment, the inventors tried to use boron oxide alone as flux, and found that using boron oxide alone as flux cannot obtain β-Ga2O3 single crystal.

[0007] The inventors consider the properties of the components when selecting the components of the fluxing agent. The inventors initially did not consider selecting bismuth oxide and bismuth oxide as components of the fluxing agent because: first, the phase diagram of the bismuth oxide-bismuth oxide binary system is less studied, and there is a lack of clear eutectic point or stable compound data, making it difficult for those skilled in the art to predict its melting behavior; second, since bismuth oxide is an acidic oxide and bismuth oxide is a weakly basic oxide, if these two are selected as components of the fluxing agent, the phase composition of the fluxing agent system may change due to the possible acid-base reaction between the two, thereby greatly changing the process, ratio, and other parameters, greatly increasing the research and development cost. Therefore, there is a technical barrier to selecting bismuth oxide and bismuth oxide as components of the fluxing agent in the prior art.

[0008] The inventors selected bismuth oxide and bismuth oxide as components of the fluxing agent because the inventors accidentally discovered that bismuth oxide forms a low-viscosity glass network at high temperatures, which can break the ion clusters of bismuth oxide, enhance the melt flowability, increase the mass transfer rate, and make it possible for the β-Ga2O3 crystal to grow at a melting temperature below 1200°C. Therefore, according to one aspect of the present application, a fluxing agent for β-Ga2O3 crystal growth is provided.

[0009] The fluxing agent for β-Ga2O3 crystal growth includes a mixture of bismuth oxide and bismuth oxide. When the fluxing agent is used for β-Ga2O3 crystal growth, it not only reduces the melting temperature to below 1200°C, achieving the purpose of low carbon, but also avoids the decomposition and volatilization of gallium oxide at high temperatures, ensuring the quality of the prepared gallium oxide; it can also be melted in an air atmosphere; it can be applied to a relatively high heating rate of 50°C / h to 200°C / h, a relatively short holding time of 3h to 8h, and a relatively high cooling rate of 5°C / h to 10°C / h to achieve the purpose of high efficiency and stability; and since the fluxing agent does not contain toxic additives such as lead oxide or fluoride, it can avoid affecting the health of the operator and the environment.

[0010] In some embodiments, the inventors found that when the ratio of bismuth oxide to bismuth oxide is not properly selected, it is difficult to obtain β-Ga2O3 crystals. Therefore, the inventors conducted a large number of experiments and found that when the molar ratio of bismuth oxide to bismuth oxide is (0.5-2):(2-5), β-Ga2O3 crystals can be obtained at a melting temperature below 1200°C. Thus, the fluxing effect of the fluxing agent on the β-Ga2O3 powder is ensured, and the melting temperature is reduced from 1820°C to below 1200°C.

[0011] According to another aspect of the present application, there is provided an application of a fluxing agent in the growth of β-Ga2O3 crystals, wherein the fluxing agent comprises a mixture of bismuth oxide and boron oxide, and the molar ratio of β-Ga2O3 powder, bismuth oxide and boron oxide ranges from 1:(0.5-2):(2-5). Thus, the heating rate and the cooling rate can be greatly increased, and the holding time can be greatly reduced, while the melting temperature is greatly reduced, so that the β-Ga2O3 crystals can be efficiently and stably prepared, and the purposes of low carbon, health and environmental protection are achieved.

[0012] According to still another aspect of the present application, there is provided a method for growing β-Ga2O3 crystals, comprising the following steps:

[0013] S10: uniformly mixing β-Ga2O3 powder with the aforementioned fluxing agent in a certain proportion to obtain raw material powder;

[0014] S20: pouring the raw material powder into a crucible and heating to melting and holding for a certain time to obtain molten raw material;

[0015] S30: cooling the molten raw material to obtain β-Ga2O3 crystal primary product.

[0016] Since the fluxing agent comprises a mixture of bismuth oxide and boron oxide, when the fluxing agent is used for the growth of β-Ga2O3 crystals, the melting temperature can be reduced to below 1200℃, the purposes of low carbon are achieved, the decomposition and volatilization of gallium oxide at high temperature are avoided, and the quality of prepared gallium oxide is ensured; the melting can be carried out in an air atmosphere; a higher heating rate of 50℃ / h-200℃ / h, a shorter holding time of 3h-8h, and a higher cooling rate of 5℃ / h-10℃ / h can be applied to achieve the purposes of high efficiency and stability; and since the fluxing agent does not contain toxic fluxing agents such as lead oxide or fluoride, the health of operators and the environment can be protected.

[0017] In some embodiments, in step S20, the atmosphere of the heating process is air. Since the fluxing agent of the present application is used, the melting temperature is reduced to below 1200℃, so that a platinum-gold crucible which is not easy to oxidize in an air atmosphere can meet the requirements, without using an iridium crucible which is easy to oxidize in an air atmosphere, so that the heating and melting treatment can be carried out in an air atmosphere, and a common muffle furnace can meet the production requirements during the heating process, thereby reducing the production cost.

[0018] In some embodiments, in step S20, the heating rate of the heating process is 50-200℃ / h. Due to the use of the solubility improver of the present application, a good melting effect can be achieved even at a heating rate of 50-200℃ / h, greatly improving the production efficiency.

[0019] In some embodiments, in step S20, the holding temperature is 1000-1200℃. The melting point of bismuth oxide is 825℃, and the melting point of boron oxide is 450℃, and the combination of the two can greatly reduce the melting temperature of the β-Ga2O3 powder, bismuth oxide and boron oxide system. Due to the use of the solubility improver of the present application, the raw materials can be melted and treated by heating to 1000-1200℃, avoiding the decomposition and volatilization of gallium oxide at high temperature, ensuring the quality of the prepared gallium oxide; the melting can also be carried out in an air atmosphere; and due to the low starting temperature of the cooling, a faster cooling can be achieved at the same cooling rate, improving the production efficiency.

[0020] In some embodiments, in step S20, the holding time is 3-8h. Due to the use of the solubility improver of the present application, a good melting effect can be achieved even at a high heating rate (50-200℃ / h), a low melting temperature (1000-1200℃), and a short holding time (3-8h), improving the production efficiency, reducing the production cost, and ensuring the preparation quality of β-Ga2O3.

[0021] In some embodiments, in step S20, the crucible is a platinum-gold crucible. Due to the use of the solubility improver of the present application, the melting temperature is reduced to below 1200℃, and the heating and melting treatment can be carried out in an air atmosphere, so that the platinum-gold crucible can meet the production requirements, avoiding the dependence on the inert and expensive iridium-gold crucible, greatly reducing the production cost.

[0022] In some embodiments, in step S20, the heating device is a muffle furnace. Due to the use of the solubility improver of the present application, the melting temperature is reduced to below 1200℃, and the heating and melting treatment can be carried out in an air atmosphere, so that the ordinary muffle furnace can meet the production requirements, thereby reducing the production cost.

[0023] In some embodiments, in step S20, the temperature is first increased to 400℃±20℃ at a rate of 200℃ / h±50℃ / h, and then increased to 1000℃-1200℃ at a rate of 50℃ / h±10℃ / h. Since the melting point of bismuth oxide is 825℃ and the melting point of boron oxide is 450℃, the temperature is first increased to below the melting points of bismuth oxide and boron oxide (400℃) at a faster rate, so that the bismuth oxide and boron oxide do not rapidly boil and overflow the crucible due to the too fast rate of temperature increase; then, the temperature is increased at a slower rate, so that the molten liquid does not overflow the crucible due to the too fast rate of temperature increase, while the production efficiency is ensured.

[0024] In some embodiments, in step S30, the temperature is first decreased to 600℃ at a rate of 5℃ / h-10℃ / h, and then cooled to room temperature with the furnace. In the process of preparing β-Ga2O3crystals, the inventors have found that the temperature for crystal growth needs to be higher than the melting temperature of the cosolvent. The melting point of bismuth oxide is 825℃ and the melting point of boron oxide is 450℃. Therefore, in the process of decreasing the temperature, the temperature is first decreased to 600℃ at a slower rate, so that the crystals can grow and grow at this temperature; then, the temperature is decreased at a faster rate of cooling with the furnace, so that the production efficiency is ensured.

[0025] In some embodiments, after step S30, the method further comprises the following steps:

[0026] S40: immersing the crucible containing the initial product of β-Ga2O3crystals in a nitric acid solution with a mass fraction of 10%-30% to remove the residues (cosolvent) and obtain the β-Ga2O3crystals. Since both bismuth oxide and boron oxide are soluble in nitric acid, the cosolvent can be separated from the β-Ga2O3crystals without damaging the β-Ga2O3crystals, and the cost can be reduced by avoiding using other complex methods to remove residues.

[0027] In some embodiments, in step S40, the temperature during the immersion process is room temperature or 140℃±10℃. Heating during the immersion process can improve the efficiency of the immersion process. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FIG. 1 is a flowchart of a method for growing β-Ga2O3crystals according to an embodiment of the present application;

[0029] Figure 2 FIG. 2 is a flowchart of a method for growing β-Ga2O3crystals according to another embodiment of the present application;

[0030] Figure 3 (a) and (b) are photographs of the molten materials after sintering of Example 1 and Comparative Example 1, respectively.

[0031] Figure 4 (a) and (b) are XRD patterns of the crystal growth face of Example 1 and the crystal powder XRD pattern of Example 2, respectively;

[0032] Figure 5 (a) and (b) are crystal photographs of Example 1 and Example 3, respectively. DETAILED DESCRIPTION

[0033] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0034] It should also be noted that, in the present text, the relational terms such as first and second and the like are used only to differentiate one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including", "containing", "involving", "having" and the like are not intended to exclude that there are other elements, components, steps, processes, materials or the like in the process, method, article or apparatus that are not expressly listed. The term "comprising", without more, does not exclude that other elements, components, steps, processes, materials or the like are present in addition to those listed. The term "consisting essentially of does not exclude the presence of other elements, components, steps, processes, materials or the like that do not materially affect the basic and novel characteristics of the process, method, article or apparatus. In the present text, the term "consisting of does not include other elements, components, steps, processes, materials or the like.

[0035] Moreover, for the purpose of describing the present application, spatial relative terms such as "below", "lower", "bottom", "above", "upper", and the like are used to describe one element or component's or portion's relationship to another element or component or portion as illustrated in the figures. The spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial relative descriptors used herein interpreted accordingly.

[0036] In the present text, the term "Baliga's Figure of Merit" (BFOM) is proposed by the electrical engineer B. Jayant Baliga to evaluate the performance potential of power semiconductor materials in high-voltage, high-power applications. This factor quantifies the trade-off between on-state resistance and breakdown voltage of a device by combining the physical properties of the material, helping to compare the theoretical performance limits of different materials. The formula for Baliga's Figure of Merit is: BFOM = ε r · μ · E c 3 where ε r: relative dielectric constant of the material (dimensionless); μ: carrier mobility (unit: cm 2 : critical breakdown field strength (unit: V / cm). c : critical breakdown field strength (unit: V / cm).

[0037] To make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments but not all of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0038] A fluxing agent for β-Ga2O3 crystal growth according to an embodiment of the present application.

[0039] The fluxing agent for β-Ga2O3 crystal growth comprises a mixture of bismuth oxide and boron oxide. When the fluxing agent is used for the crystal growth of β-Ga2O3, not only can the melting temperature be reduced to below 1200℃, achieving the purpose of low carbon, but also can avoid the decomposition and volatilization of gallium oxide at high temperature, ensuring the quality of prepared gallium oxide; the melting can be carried out in an air atmosphere; while a higher heating rate of 50℃ / h-200℃ / h is applicable, a shorter holding time of 3h-8h is applicable, and a higher cooling rate of 5℃ / h-10℃ / h is applicable, achieving the purpose of high efficiency and stability; and since the fluxing agent does not contain toxic fluxing agents such as lead oxide or fluoride, the impact on the health of operators and the environment can be avoided.

[0040] In some embodiments, the molar ratio of bismuth oxide to boron oxide ranges from (0.5-2):(2-5). Thus, the fluxing effect of the fluxing agent on the β-Ga2O3 powder can be ensured, and the melting temperature can be reduced from 1820℃ to below 1200℃.

[0041] Application of the fluxing agent according to an embodiment of the present application in the growth of β-Ga2O3 crystal, wherein the fluxing agent comprises a mixture of bismuth oxide and boron oxide, and the molar ratio of β-Ga2O3 powder, bismuth oxide and boron oxide ranges from 1:(0.5-2):(2-5). Thus, the melting temperature can be greatly reduced, the heating rate and the cooling rate can be greatly improved, and the holding time can be greatly reduced, achieving the purposes of high efficiency, stability, low carbon, health and environmental protection in the preparation of β-Ga2O3 crystal.

[0042] Figure 1 An exemplary β-Ga2O3 crystal growth method according to the first embodiment of the present application is shown, which comprises the following steps:

[0043] S10: uniformly mixing the β-Ga2O3 powder with the aforementioned fluxing agent in proportion to obtain raw material powder;

[0044] S20: pouring the raw material powder into a crucible, heating to melt and keeping the temperature for a set time to obtain molten raw material;

[0045] S30: cooling the molten raw material to obtain β-Ga2O3 crystal primary product.

[0046] In step S10, the fluxing agent includes bismuth oxide (Bi2O3) and boron oxide (B2O3), and the β-Ga2O3 powder is mixed with bismuth oxide powder and boron oxide powder in a proportion of 1:(0.5-2):(2-5). Exemplarily, the mixing process can put the mixed raw material in an agate mortar for grinding to obtain raw material powder.

[0047] In step S20, the atmosphere of the heating process is air, so that a common muffle furnace can meet the production needs during the heating process, thereby reducing the production cost. The heating rate of the heating process is 50-200℃ / h, so as to greatly improve the production efficiency while ensuring the melting effect. First, the temperature is raised to 400±20℃ at a rate of 200±50℃ / h, and then the temperature is raised to 1000-1200℃ at a rate of 50±10℃ / h. The temperature for keeping warm is 1000-1200℃, so as to avoid the decomposition and volatilization of gallium oxide at high temperature under the condition that the raw material powder can be melted and treated, and ensure the quality of the prepared gallium oxide; and since the starting temperature of the cooling is low, the cooling can be faster at the same cooling rate, thereby improving the production efficiency. The set time for keeping warm is 3-8h, so as to ensure the melting effect, improve the production efficiency, reduce the production cost, and ensure the preparation quality of β-Ga2O3. The crucible is a platinum-gold crucible, so as to greatly reduce the production cost. The heating equipment is a muffle furnace, so as to reduce the production cost.

[0048] In step S30, the temperature is first reduced to 500℃ at a rate of 5-10℃ / h, and then the furnace is cooled to room temperature.

[0049] The flux solvent includes a mixture of bismuth oxide and boron oxide. When the flux solvent is used for the crystal growth of β-Ga2O3, the melting temperature can be reduced to below 1200℃, the purpose of low carbon is achieved, the decomposition and volatilization of gallium oxide at high temperature are avoided, the quality of prepared gallium oxide is ensured, the melting can be carried out in an air atmosphere, a high heating rate of 50℃ / h-200℃ / h can be applied, a short holding time of 3h-8h can be applied, a high cooling rate of 5℃ / h-10℃ / h can be applied, the purposes of high efficiency and stability are achieved, and the health of operators and the environment can be protected because the flux solvent does not contain toxic flux agents such as lead oxide and fluoride.

[0050] Figure 2 The β-Ga2O3 crystal growth method of the second embodiment of the present application is exemplarily shown, which comprises the following steps after the first embodiment of the β-Ga2O3 crystal growth method:

[0051] S40: The crucible containing the β-Ga2O3 crystal primary product is soaked with a nitric acid solution with a mass fraction of 10%-30% to remove the residues and obtain the β-Ga2O3 crystal. In this way, the β-Ga2O3 crystal can be separated from the flux solvent without damaging the β-Ga2O3 crystal.

[0052] In some embodiments, the temperature of the soaking process in step S40 is room temperature or 140℃±10℃ to improve the soaking efficiency.

[0053] The β-Ga2O3 crystal growth method of the present application is exemplarily described below in combination with specific examples.

[0054] The gallium oxide powder used in the examples has a purity of 99.99%, the bismuth oxide powder has a purity of 99.99%, and the boron oxide powder has a purity of 99.9%. The experimental methods described in the examples are conventional methods, and the reagents, materials and equipment involved can be obtained through commercial channels.

[0055] Example 1

[0056] The gallium oxide powder, the bismuth oxide powder and the boron oxide powder are weighed according to a molar ratio of 1:1:3, put into an agate mortar, and thoroughly ground and mixed to obtain raw material powder.

[0057] Subsequently, the mixed raw material powder is loaded into a platinum crucible with a diameter of 40mm and a height of 50mm, and the platinum crucible loaded with the raw material powder is placed at the center of a muffle furnace. The raw material powder is heated to 400℃ at a heating rate of 200℃ / h in an air atmosphere, and then heated to 1000℃ at a heating rate of 100℃ / h, and held for 8h.

[0058] After the melt is mixed thoroughly, the temperature is decreased to 500°C at a rate of 10°C / h, and then the furnace is cooled to room temperature.

[0059] After the temperature is decreased to room temperature, the platinum crucible is removed from the muffle furnace, and the crucible is soaked in a 10% nitric acid solution heated to 140°C to remove residues, thereby obtaining β-Ga2O3 crystals.

[0060] The present example can obtain crystals as shown in Figure 5 (a).

[0061] Example 2

[0062] Gallium oxide, bismuth oxide and boron oxide powders are weighed in a molar ratio of 1:1:3, and are put into an agate mortar to be mixed and ground thoroughly, thereby obtaining raw material powders.

[0063] The mixed raw material powders are then put into a platinum crucible with a diameter of 40 mm and a height of 50 mm, and the platinum crucible with the raw material powders is put in the center of a muffle furnace. The temperature is increased to 1200°C at a rate of 200°C / h under an air atmosphere, and is maintained for 4 h.

[0064] After the melt is mixed thoroughly, the temperature is decreased to 550°C at a rate of 10°C / h, and then the furnace is cooled to room temperature.

[0065] After the temperature is decreased to room temperature, the platinum crucible is removed from the muffle furnace, and the crucible is soaked in a 10% nitric acid solution heated to 140°C to remove residues, thereby obtaining β-Ga2O3 crystals.

[0066] In the present example, although the melt overflows due to a too fast heating rate, crystals with a mass substantially the same as that of the crystals in Figure 5 (b) are ultimately obtained.

[0067] Example 3

[0068] Gallium oxide, bismuth oxide and boron oxide powders are weighed in a molar ratio of 1:2:5, and are put into an agate mortar to be mixed and ground thoroughly, thereby obtaining raw material powders.

[0069] The mixed raw material powders are then put into a platinum crucible with a diameter of 40 mm and a height of 50 mm, and the platinum crucible with the raw material powders is put in the center of a muffle furnace. The temperature is increased to 400°C at a rate of 200°C / h under an air atmosphere, and is then increased to 1000°C at a rate of 60°C / h, and is maintained for 6 h.

[0070] After the melt is mixed thoroughly, the temperature is decreased to 500°C at a rate of 10°C / h, and then the furnace is cooled to room temperature.

[0071] After the temperature dropped to room temperature, the platinum crucible was taken out of the muffle furnace, and the crucible was soaked with a 30% by mass nitric acid solution to remove residues, thereby obtaining β-Ga2O3crystals.

[0072] The crystals obtained in this example have Figure 5 (b) shown.

[0073] Example 4

[0074] Gallium oxide, bismuth oxide and boron oxide powders were weighed in a ratio of 1 : 2 : 5 by mole, and were thoroughly mixed and ground in an agate mortar to obtain raw material powders.

[0075] The mixed raw material powders were then loaded into a platinum crucible having a diameter of 40 mm and a height of 50 mm, and the platinum crucible loaded with the raw material powders was placed in the center of a muffle furnace. The platinum crucible was heated to 400°C at a temperature increase rate of 200°C / h under an air atmosphere, and then heated to 1100°C at a temperature increase rate of 50°C / h. The temperature was maintained for 4 hours.

[0076] After the melt was thoroughly mixed, the temperature was decreased to 500°C at a rate of 5°C / h, and then the furnace was allowed to cool to room temperature.

[0077] After the temperature dropped to room temperature, the platinum crucible was taken out of the muffle furnace, and the crucible was soaked with a 20% by mass nitric acid solution heated to 140°C to remove residues, thereby obtaining β-Ga2O3crystals.

[0078] The crystals obtained in this example have Figure 5 (a) substantially the same quality.

[0079] Comparative Example 1

[0080] Gallium oxide, bismuth oxide and boron oxide powders were weighed in a ratio of 1 : 1 : 6 by mole, and were thoroughly mixed and ground in an agate mortar to obtain raw material powders.

[0081] The mixed raw material powders were then loaded into a platinum crucible having a diameter of 40 mm and a height of 50 mm, and the platinum crucible loaded with the raw material powders was placed in the center of a muffle furnace. The platinum crucible was heated to 400°C at a temperature increase rate of 200°C / h under an air atmosphere, and then heated to 1000°C at a temperature increase rate of 50°C / h. The temperature was maintained for 8 hours.

[0082] After the melt was thoroughly mixed, the temperature was decreased to 500°C at a rate of 10°C / h, and then the furnace was allowed to cool to room temperature.

[0083] After the temperature dropped to room temperature, the platinum crucible was taken out of the muffle furnace, and the crucible was soaked with a 20% by mass nitric acid solution at room temperature to remove residues, thereby obtaining a small amount of β-Ga2O3crystals.

[0084] The content of boron oxide in the present comparative example is relatively high, and the melt viscosity is too large (for example Figure 3 The viscosity shown in (b) of FIG. 1 in the present comparative example is greater than the viscosity of Example 1 Figure 3 The viscosity shown in (a) of FIG. 1 in the present comparative example), resulting in a small amount of crystals precipitated.

[0085] Comparative Example 2

[0086] Gallium oxide and boron oxide powders are weighed according to a molar ratio of 1:3, and are put into an agate mortar to be mixed and ground uniformly to obtain raw material powders.

[0087] The mixed raw material powders are then put into a platinum crucible with a diameter of 40 mm and a height of 50 mm, and the platinum crucible with the raw material powders is placed at the center of a muffle furnace. The raw material powders are heated to 400°C at a heating rate of 200°C / h under an air atmosphere, and then heated to 1000°C at a heating rate of 50°C / h, and are kept at 1000°C for 6 h.

[0088] After the melt is mixed sufficiently, the temperature is decreased to 500°C at a rate of 8°C / h, and then the furnace is cooled to room temperature.

[0089] After the temperature is decreased to room temperature, the platinum crucible is taken out of the muffle furnace, and the crucible is soaked in a 20% nitric acid solution at room temperature.

[0090] In the present comparative example, only boron oxide is used as a fluxing agent, and the melt viscosity is very large, resulting in that a gallium oxide single crystal cannot be prepared.

[0091] The above only describes some embodiments of the present application. For those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application.

Claims

1. A cosolvent for β-Ga203 crystal growth, characterized by, The complex includes bismuth oxide and boron oxide, and the molar ratio of bismuth oxide to boron oxide ranges from (0.5-2):(2-5).

2. Use of a cosolvent in the growth of β-Ga203 crystals, characterized in that, The complex includes bismuth oxide and boron oxide, and the molar ratio of the β-Ga2O3 powder, bismuth oxide and boron oxide ranges from 1:(0.5-2):(2-5).

3. A method for growing β-Ga2O3 crystal, characterized in comprising the following steps: S10: uniformly mixing the β-Ga2O3 powder with the complex of any one of claims 1-2 in a proper ratio to obtain raw material powder; S20: pouring the raw material powder into a crucible, heating to melt and keeping the temperature for a set time to obtain molten raw material; S30: cooling the molten raw material to obtain β-Ga2O3 crystal primary product.

4. The β-Ga203 crystal growth method according to claim 3, characterized by, In step S20, the atmosphere of the heating process is air; and / or In step S20, the heating rate of the heating process is 50-200 ℃ / h.

5. The β-Ga2O3 crystal growth method according to claim 3, characterized by, In step S20, the temperature of the keeping temperature is 1000-1200 ℃; and / or In step S20, the set time of the keeping temperature is 3-8 h.

6. The β-Ga203 crystal growth method according to claim 3, characterized by, In step S20, the crucible is a platinum-gold crucible; and / or In step S20, the heating device is a muffle furnace.

7. The β-Ga203 crystal growth method according to claim 3, characterized by, In step S30, the cooling is first at a cooling rate of 5-10 ℃ / h to 500 ℃, and then the furnace is cooled to room temperature; and / or In step S20, the temperature is first raised to 400±20 ℃ at a rate of 200±50 ℃ / h, and then raised to 1000-1200 ℃ at a rate of 50±10 ℃ / h.

8. The β-Ga2O3 crystal growth method according to any one of claims 3 to 7, characterized by, After step S30, the following step is further included: S40: immersing the crucible containing the β-Ga2O3 crystal primary product in a 10-30% nitric acid solution to remove residues to obtain β-Ga2O3 crystal.

9. The β-Ga203 crystal growth method according to claim 8, characterized by, In step S40, the temperature of the immersion process is room temperature or 140±10 ℃.

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