A covering agent for gallium antimonide surface growth and a preparation method thereof

Abstract

The application discloses a covering agent for surface growth of gallium antimonide and a preparation method thereof, and relates to the technical field of semiconductor materials. In the preparation of the covering agent for surface growth of gallium antimonide, sodium chloride and potassium chloride are used as a base, high-purity rubidium chloride is doped as a modified component, a segmented temperature-pressure coupling purification process is adopted, adsorbed water, crystal water and volatile impurities of sulfate are removed in a vacuum condition in a segmented manner from room temperature to 600 DEG C, the temperature is raised under the protection of a micro-positive pressure of argon, constant-temperature refining is carried out, the temperature is lowered, the material is discharged, and the surface scum is peeled off, so as to obtain the surface covering agent for growth of gallium antimonide. The preparation process can completely eliminate the water and oxygen impurities in the molten salt, and the prepared covering agent for surface growth of gallium antimonide has the performances of low high-temperature loss, strong spreading capacity and low internal adsorbed water.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials technology, specifically to a covering agent for gallium antimonide surface growth and its preparation method. Background Technology

[0002] The liquid-sealed Czochralski method is one of the mainstream processes for preparing large-size, high-quality gallium antimonide single crystals. During the heating and melting stage, the gallium antimonide growth raw material is very prone to oxidation reaction with water vapor and oxygen in the furnace to generate oxide slag. At the same time, the high saturated vapor pressure of antimony makes it easy to volatilize in large quantities, causing an imbalance in crystal composition. Therefore, the surface of the melt must be covered with a liquid covering agent to isolate the gas phase and inhibit antimony volatilization. The purity and comprehensive performance of the covering agent directly determine the single crystal defect density, electrical uniformity and production yield.

[0003] Currently, industrial mass production of gallium antimonide single crystals commonly uses NaCl-KCl binary eutectic chloride salts as liquid sealing agents. This system has readily available raw materials, a melting point suitable for GaSb crystal growth temperatures, and basic liquid sealing protection capabilities, leading to its widespread adoption. However, NaCl and KCl have high vapor pressures at high temperatures, resulting in continuous evaporation and loss of molten salt during crystal growth, rapid decay of the liquid seal thickness, and the need for frequent molten salt replenishment. The evaporating salts can also corrode furnace tubes and vacuum units, leading to high consumable and equipment maintenance costs. Furthermore, the resulting molten salt ion network is loose, limiting the antimony vapor diffusion barrier effect across the liquid seal, easily forming Sb vacancy defects, and degrading the minority carrier lifetime of infrared devices. Additionally, existing binary NaCl-KCl covering agents have high viscosity, poor spreadability at crucible edges, and are prone to creating weak areas in the liquid film, causing instantaneous oxidation. Oxidation scum is difficult to separate, resulting in a high proportion of oxidation inclusion defects.

[0004] In summary, there is an urgent need to develop a novel molten salt covering agent that is low in volatility, low in corrosion, has excellent spreadability, and is recyclable, in order to meet the requirements for stable industrial production of high-quality gallium antimonide single crystals. Summary of the Invention

[0005] The purpose of this invention is to provide a covering agent for gallium antimonide surface growth and its preparation method, so as to solve the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following solution: A gallium antimonide surface growth covering agent, wherein the gallium antimonide surface growth covering agent is based on sodium chloride and potassium chloride, doped with modified components, and is obtained by a segmented temperature and pressure coupling purification process, wherein the temperature is raised from room temperature to 550~650℃, and adsorbed water, crystal water and sulfate volatile impurities are removed in stages under vacuum conditions, and the temperature is raised under argon micro positive pressure protection, isothermal refining, cooling, discharge and peeling off the surface slag. As an optimization, the modified component is high-purity rubidium chloride.

[0007] A method for preparing a covering agent for gallium antimonide surface growth, the method comprising the following preparation steps: (1) Mix sodium chloride and potassium chloride evenly, add 0.005~0.015 times the total mass of rubidium chloride and mix evenly. Place the mixture in a sealed alumina ball mill jar and heat it at 10 ... -3 Ball milling under vacuum conditions for 10-20 minutes, then loading into a quartz boat with an alumina liner to obtain a material boat; (2) The quartz tube is ignited at 1000~1200℃ for 1~3h, placed in an alumina heat-insulating cup, the material boat is pushed into the bottom of the tube, the flange is sealed with double-layer fluororubber, and under vacuum conditions, it is dehydrated at low temperature for 1~2h, removed impurities at medium temperature for 50~70min, refined at high temperature for 3~4h, the bubbling is stopped, and it is kept at constant temperature for 30~50min to separate into layers. The temperature is lowered to 300~340℃, the vacuum system is restarted, and it is naturally cooled to 50~60℃. The vacuum pump is stopped, argon is charged to atmospheric pressure, the tube is opened, and the surface slag containing impurities is peeled off to obtain the surface covering agent for gallium antimonide growth.

[0008] As an optimization, the molar ratio of sodium chloride to potassium chloride is 1:1.

[0009] As an optimization, the process parameters for the low-temperature dehydration are as follows: under vacuum conditions, the temperature is increased to 300-400℃ at a rate of 1-2℃ / min, and then calcined for 1-2 hours.

[0010] As an optimization, the process parameters for the medium-temperature impurity removal are as follows: heat to 550~650℃ at a rate of 0.5~1.5℃ / min, close the vacuum valve, and calcine for 50~70min under argon protection at 0.01~0.03MPa.

[0011] As an optimization, the process parameters for the high-temperature refining are as follows: heating to 760-800℃ at a rate of 0.6-1℃ / min, using 2-4 min of ventilation, 4-6 min of standing, and refining for 3-4 h with circulating pulsed argon gas.

[0012] As an optimization, the process parameters for cooling to 300~340℃ are as follows: under argon protection of 0.01~0.03MPa, the temperature is reduced to 300~340℃ at a rate of 0.5~0.7℃ / min.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are: First, this system uses NaCl-KCl binary eutectic as the substrate, with trace amounts of rubidium chloride as a modifying component; under high-temperature molten conditions, low vapor pressure Rb... + Spontaneous enrichment at the molten salt gas-liquid interface forms a dense barrier layer, with a large radius Rb + With Cl -The association of stable ion clusters reduces the activity of NaCl and KCl, significantly suppressing the volatilization of alkali metal chlorides from a thermodynamic perspective. This reduces the loss of surface covering agents used in gallium antimonide growth, ensuring stable liquid-sealed thickness throughout the crystal growth process without frequent refueling; Rb + It also breaks the regular ionic grid of binary salts, reduces the viscosity and interfacial tension of molten salt, thereby improving the spreading ability of the surface covering agent used for gallium antimonide growth. During use, it can completely cover the edges and corners of the crucible, eliminate weak oxygen leakage areas in the liquid film, and enable the floating oxide slag to be separated quickly, reducing oxide inclusions, dislocations, and twin defects in gallium antimonide crystals, thereby improving the lattice integrity and photoelectric performance of gallium antimonide single crystals.

[0014] Secondly, the entire segmented temperature-pressure process relies on the coordinated use of temperature, vacuum, and atmosphere to remove impurities in layers. A high vacuum is maintained throughout the process from room temperature to 600℃. In the low-temperature range, adsorbed water and lattice-bound water from the salt powder are fully removed. At medium temperatures, gaseous impurities generated by the decomposition of sulfates and hydroxides are continuously removed, preventing the high-temperature hydrolysis of chlorides to generate hydrogen chloride, which in turn oxidizes the gallium antimonide raw material. Once the temperature reaches 600℃, a slight positive pressure of argon gas is switched to prevent the large-scale removal of chlorides at high temperatures, which would cause raw material loss. In the refining stage, pulsed argon bubbling is used; the rising of bubbles carries dissolved oxygen and microbubbles from the molten salt, and the airflow disturbance promotes the removal of Rb. + Uniform dispersion forms a single-phase homogeneous ternary eutectic; the entire cooling stage is protected by argon gas to prevent the molten salt from adsorbing water vapor in the pipeline. The vacuum is turned on after the molten salt has completely solidified, and only the residual water vapor on the pipe wall is removed to prevent the finished product from being moistened again and introducing oxygen impurities. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1: A method for preparing a covering agent for gallium antimonide surface growth, the method comprising the following steps: (1) Mix sodium chloride and potassium chloride in a molar ratio of 1:1 until homogeneous, add 0.01 times the total mass of rubidium chloride and mix until homogeneous. Place the mixture in a sealed alumina ball mill jar and heat for 10 minutes. -3 Ball milling under vacuum conditions for 20 minutes, then loading the material into a quartz boat with an alumina liner, thus obtaining a material boat; (2) The quartz tube was ignited at 1000℃ for 3 hours, placed in an alumina heat-insulating cup, and the material boat was pushed into the bottom of the tube. The flange was sealed with double-layer fluororubber. Under vacuum conditions, the temperature was increased to 300℃ at a rate of 1℃ / min and ignited for 2 hours. The temperature was increased to 600℃ at a rate of 0.5℃ / min. The vacuum valve was closed, and the tube was ignited for 70 minutes under argon protection at 0.01MPa. The temperature was increased to 780℃ at a rate of 0.6℃ / min. The tube was bubbled with circulating pulse argon for 4 minutes and left to stand for 6 minutes. The tube was refined for 4 hours. The bubbling was stopped, and the tube was left to stand at a constant temperature for 50 minutes to separate into layers. Under argon protection at 0.01MPa, the tube was cooled to 320℃ at a rate of 0.5℃ / min. The vacuum system was restarted, and the tube was allowed to cool naturally to 50℃. The vacuum pump was stopped, and the tube was filled with argon to atmospheric pressure. The tube was opened, and the surface slag containing impurities was peeled off to obtain the surface covering agent for gallium antimonide growth.

[0017] Example 2: A method for preparing a covering agent for gallium antimonide surface growth, the method comprising the following steps: (1) Mix sodium chloride and potassium chloride in a molar ratio of 1:1 until homogeneous, add 0.01 times the total mass of rubidium chloride and mix until homogeneous. Place the mixture in a sealed alumina ball mill jar and heat for 10 minutes. -3 Ball milling under vacuum conditions for 15 minutes, then loading the material into a quartz boat with an alumina liner, thus obtaining a material boat; (2) The quartz tube was ignited at 1100℃ for 2 hours, placed in an alumina heat-insulating cup, and the material boat was pushed into the bottom of the tube. The flange was sealed with double-layer fluororubber. Under vacuum conditions, the temperature was raised to 350℃ at a rate of 1.5℃ / min and ignited for 1.5 hours. The temperature was raised to 600℃ at a rate of 1℃ / min. The vacuum valve was closed, and the tube was ignited for 60 minutes under 0.02MPa argon protection. The temperature was raised to 780℃ at a rate of 0.8℃ / min. The tube was bubbled with circulating pulse argon for 3 minutes and then left to stand for 5 minutes. The tube was refined for 3.5 hours. The bubbling was stopped, and the tube was left to stand at a constant temperature for 40 minutes to separate into layers. Under 0.02MPa argon protection, the tube was cooled to 320℃ at a rate of 0.6℃ / min. The vacuum system was restarted, and the tube was allowed to cool naturally to 55℃. The vacuum pump was stopped, and the tube was filled with argon to atmospheric pressure. The tube was opened, and the surface slag containing impurities was peeled off to obtain the surface covering agent for gallium antimonide growth.

[0018] Example 3: A method for preparing a covering agent for gallium antimonide surface growth, the method comprising the following steps: (1) Mix sodium chloride and potassium chloride in a molar ratio of 1:1 until homogeneous, add 0.01 times the total mass of rubidium chloride and mix until homogeneous. Place the mixture in a sealed alumina ball mill jar and heat for 10 minutes. -3 Ball milling under vacuum conditions for 10 minutes, then loading the material into a quartz boat with an alumina liner, thus obtaining a material boat; (2) The quartz tube was ignited at 1200℃ for 1 hour, placed in an alumina heat-insulating cup, and the material boat was pushed into the bottom of the tube. The flange was sealed with double-layer fluororubber. Under vacuum conditions, the temperature was increased to 400℃ at a rate of 2℃ / min and ignited for 1 hour. The temperature was increased to 600℃ at a rate of 1.5℃ / min. The vacuum valve was closed, and the tube was ignited for 50 minutes under 0.03MPa argon protection. The temperature was increased to 780℃ at a rate of 1℃ / min. The tube was bubbled with circulating pulse argon for 2 minutes and then left to stand for 4 minutes. The tube was refined for 3 hours. The bubbling was stopped, and the tube was left to stand at a constant temperature for 30 minutes to separate into layers. Under 0.03MPa argon protection, the tube was cooled to 320℃ at a rate of 0.7℃ / min. The vacuum system was restarted, and the tube was allowed to cool naturally to 60℃. The vacuum pump was stopped, and the tube was filled with argon to atmospheric pressure. The tube was opened, and the surface slag containing impurities was peeled off to obtain the surface covering agent for gallium antimonide growth.

[0019] Comparative Example 1: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 1 differs from that in Example 2 only in that the molar ratio of sodium chloride to potassium chloride in step (1) is changed to 0.9:1. The remaining steps are the same as in Example 2.

[0020] Comparative Example 2: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 2 differs from that in Example 2 only in that the molar ratio of sodium chloride and potassium chloride in step (1) is changed to 1:0.9. The remaining steps are the same as in Example 2.

[0021] Comparative Example 3: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 3 differs from that in Example 2 only in that rubidium chloride is not added in step (1). The remaining steps are the same as in Example 2.

[0022] Comparative Example 4: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 4 differs from that in Example 2 only in that the amount of rubidium chloride added in step (1) is changed to 0.005 times the total mass. The remaining steps are the same as in Example 2.

[0023] Comparative Example 5: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 5 differs from that in Example 2 only in that the amount of rubidium chloride added in step (1) is changed to 0.008 times the total mass. The remaining steps are the same as in Example 2.

[0024] Comparative Example 6: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 6 differs from that in Example 2 only in that the amount of rubidium chloride added in step (1) is changed to 0.012 times the total mass. The remaining steps are the same as in Example 2.

[0025] Comparative Example 7: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 7 differs from that in Example 2 only in that the amount of rubidium chloride added in step (1) is changed to 0.015 times the total mass. The remaining steps are the same as in Example 2.

[0026] Comparative Example 8: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 8 differs from that in Example 2 only in that the phrase "heating to 600°C at a rate of 1°C / min and closing the vacuum valve" in step (2) is changed to "heating to 500°C at a rate of 1°C / min and closing the vacuum valve". The remaining steps are the same as in Example 2.

[0027] Comparative Example 9: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 9 differs from that in Example 2 only in that step (2) "heating to 600°C at a rate of 1°C / min and closing the vacuum valve" is changed to "heating to 550°C at a rate of 1°C / min and closing the vacuum valve". The remaining steps are the same as in Example 2.

[0028] Comparative Example 10: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 10 differs from that in Example 2 only in that the phrase "heating to 600°C at a rate of 1°C / min and closing the vacuum valve" in step (2) is changed to "heating to 650°C at a rate of 1°C / min and closing the vacuum valve". The remaining steps are the same as in Example 2.

[0029] Comparative Example 11: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 11 differs from that in Example 2 only in that the phrase "heating to 600°C at a rate of 1°C / min and closing the vacuum valve" in step (2) is changed to "heating to 700°C at a rate of 1°C / min and closing the vacuum valve". The remaining steps are the same as in Example 2.

[0030] Comparative Example 12: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 12 differs from that in Example 2 only in that "heating to 780°C at a rate of 0.8°C / min" in step (2) is changed to "heating to 740°C at a rate of 0.8°C / min". The remaining steps are the same as in Example 2.

[0031] Comparative Example 13: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 13 differs from that in Example 2 only in that "heating to 780°C at a rate of 0.8°C / min" in step (2) is changed to "heating to 760°C at a rate of 0.8°C / min". The remaining steps are the same as in Example 2.

[0032] Comparative Example 14: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 14 differs from that in Example 2 only in that "heating to 780°C at a rate of 0.8°C / min" in step (2) is changed to "heating to 800°C at a rate of 0.8°C / min". The remaining steps are the same as in Example 2.

[0033] Comparative Example 15: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 15 differs from that in Example 2 only in that "heating to 780°C at a rate of 0.8°C / min" in step (2) is changed to "heating to 820°C at a rate of 0.8°C / min". The remaining steps are the same as in Example 2.

[0034] Comparative Example 16: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 16 differs from that in Example 2 only in that the step (2) of "using 3 min of ventilation and 5 min of standing with circulating pulsed argon gas" is omitted. The remaining steps are the same as in Example 2.

[0035] Comparative Example 17: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 17 differs from that in Example 2 only in that the step (2) of "using circulating pulsed argon gas bubbling for 3 min and standing for 5 min" is changed to "using continuous constant flow argon gas bubbling". The remaining steps are the same as in Example 2.

[0036] Comparative Example 18: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 18 differs from that in Example 2 only in that the phrase "cool down to 320°C at a rate of 0.6°C / min and restart the vacuum system" in step (2) is changed to "cool down to 300°C at a rate of 0.6°C / min and restart the vacuum system". The remaining steps are the same as in Example 2.

[0037] Comparative Example 19: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 19 differs from that in Example 2 only in that the phrase "cool down to 320°C at a rate of 0.6°C / min and restart the vacuum system" in step (2) is changed to "cool down to 340°C at a rate of 0.6°C / min and restart the vacuum system". The remaining steps are the same as in Example 2.

[0038] Comparative Example 20: The preparation method of the covering agent for gallium antimonide surface growth in Comparative Example 20 differs from that in Example 2 only in that "cooling down to 320°C at a rate of 0.6°C / min and restarting the vacuum system" in step (2) is changed to "cooling down to 360°C at a rate of 0.6°C / min and restarting the vacuum system". The remaining steps are the same as in Example 2.

[0039] Test Example 1 Optimal addition ratio test of covering agent for gallium antimonide surface growth Test method: High-temperature volatilization loss test method: 15 mg of the gallium antimonide surface growth covering agent of the example or comparative example was loaded into an alumina crucible. Under argon protection, the temperature was increased to 900°C at a rate of 0.8°C / min. Every 4 hours, the crucible was removed, placed in a desiccator to cool to room temperature, and weighed. The thermal stability temperature and remaining mass fraction of the mixed molten salt sample were recorded.

[0040] Viscosity testing method: Using an RTW-10 melt property analyzer, 15 mg of the gallium antimonide surface growth covering agent from the examples and comparative examples was placed in an alumina crucible. Under argon protection, the temperature was increased to 720°C at a rate of 0.8°C / min and held for 40 min. The rotor was then immersed in the liquid phase, and the dynamic viscosity was recorded. The results are shown in Table 1.

[0041] Table 1. Test results of different addition ratios of covering agent for gallium antimonide surface growth

[0042] By comparing the test results of the covering agent used for gallium antimonide surface growth in Examples 1-3 and Comparative Examples 1-2, the optimal eutectic ratio of the NaCl-KCl binary system is a molar ratio of 1:1. Deviation from this ratio will result in uneven ion mesh arrangement, which will lead to increased molten salt viscosity, narrowing of the thermal stability temperature range, increased volatilization loss, and dead zones in the liquid surface spreading. During use, oxygen and antimony vapor will easily penetrate the liquid seal, causing a large amount of gallium antimonide oxidation and an increase in crystal defects.

[0043] By comparing the test results of the covering agent used for gallium antimonide surface growth in Examples 1-3 and Comparative Examples 3-7, Rb + Can react with free Cl - Low-activity associated ion clusters are generated. As the amount of rubidium chloride added increases, the thermally stable liquid range of the molten salt widens, the viscosity continues to decrease, and the volatilization loss decreases. When the amount added is insufficient, the modification effect is weak. When the amount added exceeds 1%, the performance improvement is minimal, but the cost of high-purity rubidium chloride raw materials increases significantly, and the overall cost-effectiveness decreases. Therefore, the optimal amount of rubidium chloride added is 1%.

[0044] Test Example 2 Optimal preparation conditions for covering agents used in gallium antimonide surface growth were tested. Test method: Test method for the amount of oxide slag generated during gallium antimonide crystal growth: 20g of gallium antimonide polycrystalline raw material was spread evenly on the bottom of a quartz crucible, covered with 12g of the gallium antimonide surface growth covering agent from the examples or comparative examples, and placed in the constant temperature zone of a tube furnace. Alumina heat-insulating plugs were inserted at both ends to seal the furnace tube. Under argon protection, the temperature was increased to 780℃ at a rate of 0.8℃ / min and held at that temperature for 4 hours. After the holding period, the temperature was decreased to 300℃ at a rate of 0.6℃ / min, the argon gas was turned off, and the furnace tube was allowed to cool naturally to room temperature. The crucible was then transferred to a glove box and removed. The grayish-white oxide slag on the surface of the molten salt was completely scraped off with a scraper. The upper solidified molten salt was slowly separated, and the thin oxide layer adhering to the surface of the gallium antimonide raw material was collected. All slag was combined and placed on filter paper, dried at 120℃ for 2 hours, and the amount of slag generated was weighed and recorded. The results are shown in Table 2.

[0045] Viscosity test method: Same as the viscosity test method in Test Example 1. Results are shown in Table 3.

[0046] XRD phase testing method: The covering agent used for gallium antimonide surface growth in the examples or comparative examples was ground to 300 mesh, compacted on the XRD sample stage, and tested using an X-ray diffractometer. The scanning angle was 10°~80°, the scanning rate was 2° / min, the tube voltage was 40kV, and the tube current was 40mA. Diffraction patterns were acquired, and the 2θ angle and peak intensity data of all diffraction peaks were exported. The sample peak positions were compared with standard cards for pure sodium chloride, pure potassium chloride, and pure rubidium chloride. The results are shown in Table 3.

[0047] Table 2. Test results of different preparation conditions for the covering agent used for gallium antimonide surface growth.

[0048] By comparing the test results of the covering agent used for gallium antimonide surface growth in Examples 1-3 and Comparative Examples 8-11, it was found that a full-process high vacuum below 600°C can effectively remove molten salt adsorbed water, lattice water, and sulfate decomposition impurities, avoiding the high-temperature hydrolysis of water into chlorides to generate HCl and oxidize gallium antimonide. If the vacuum is closed prematurely (500 / 550°C), the impurities are not completely removed, and the amount of slag generated increases significantly. If the vacuum is closed delayed (650 / 700°C), the chloride vapor pressure increases sharply at high temperatures, and vacuum suction will cause a large amount of molten salt to evaporate and be lost, increasing the consumption of consumables. Therefore, the optimal temperature for heating and closing the vacuum is 600°C.

[0049] By comparing the test results of the covering agent for gallium antimonide surface growth in Examples 1-3 and Comparative Examples 16-17, pulsed bubbling can remove dissolved oxygen in the molten salt during the aeration stage and avoid water vapor entrainment by the airflow during the settling stage, thus minimizing oxygen impurities in the molten salt water; without bubbling, internal oxidizing impurities cannot be discharged; continuous bubbling will continuously entrain trace amounts of external water vapor and disperse the scum, both of which will aggravate the high-temperature oxidation of gallium antimonide, resulting in a significantly higher amount of scum generated than with pulsed bubbling; therefore, the preferred process of this scheme is pulsed bubbling.

[0050] By comparing the test results of the covering agents used for gallium antimonide surface growth in Examples 1-3 and Comparative Examples 18-20, the solidification point of the molten salt in the system is about 350°C. When the vacuum is restarted at 320°C, the molten salt is completely solid and will not absorb water vapor from the pipeline, resulting in secondary water absorption. If the vacuum is turned on at 340 / 360°C, the molten salt will absorb residual water vapor from the pipeline in the opposite direction, increasing the moisture content of the finished product and significantly increasing the oxide slag during crystal growth. Although there is no risk of water absorption when the vacuum is restarted at 300°C, the energy consumption of the vacuum equipment is higher at low temperatures, and there is no practical process advantage. Therefore, the optimal temperature for cooling and turning on the vacuum is 320°C.

[0051] Table 3. Test results of molten salt refining conditions for the covering agent used in gallium antimonide surface growth.

[0052] Comparing the test results of the covering agent used for gallium antimonide surface growth in Examples 1-3 and Comparative Examples 12-15, 780℃ is much higher than the eutectic melting point of the system (667℃). The molten salt completely melts, and the ion migration rate is sufficient to allow Rb to grow. + Uniformly dispersed Na embedded + / K + The mesh fully forms associated ions; when the refining temperature is too low, the molten salt ion migration rate is insufficient, Rb + It is prone to local agglomeration, with high frictional resistance within the ionic grid, resulting in significantly higher melt viscosity. Rubidium chloride cannot be uniformly dispersed, and independent rubidium chloride crystalline phases precipitate upon cooling. When the temperature exceeds 780℃, the interionic forces further weaken, and the viscosity decreases slightly. However, the high temperature will cause trace amounts of sodium chloride to volatilize, causing the system to deviate from the 1:1 eutectic ratio, and trace amounts of sodium chloride single phase will precipitate upon cooling. Therefore, the optimal temperature for molten salt refining is 780℃.

[0053] By comparing the test results of the covering agents used for gallium antimonide surface growth in Examples 1-3 and Comparative Examples 16-17, pulsed bubbling intermittent stirring of the melt promotes the uniform dispersion of rubidium ions to form low-resistance associated ion clusters without causing salt component volatilization, resulting in the lowest viscosity. Without bubbling, local agglomeration of rubidium salts occurs, increasing the melt flow resistance. Continuous bubbling washes the liquid surface, causing a trace loss of sodium chloride. After the ratio becomes unbalanced, the uniformity of the melt decreases, and the viscosity is higher than that of pulsed bubbling. At the same time, the gentle stirring of pulsed bubbling allows rubidium ions to be uniformly integrated into the sodium-potassium chloride lattice, forming a single ternary eutectic phase with no single salt diffraction peaks. Without bubbling, the lack of stirring leads to the local enrichment of rubidium salts and the precipitation of independent crystalline phases, with the detection of RbCl characteristic peaks. Continuous bubbling results in the loss of a small amount of sodium chloride, and the ratio becomes unbalanced, precipitating trace amounts of NaCl crystalline phases, with weak sodium chloride diffraction peaks. Therefore, the preferred process of this scheme is pulsed bubbling.

[0054] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A covering agent for gallium antimonide surface growth, characterized in that, The covering agent for gallium antimonide surface growth is based on sodium chloride and potassium chloride, doped with modified components, and is obtained by a segmented temperature-pressure coupling purification process. The temperature is raised from room temperature to 550~650℃, and adsorbed water, crystal water and sulfate volatile impurities are removed in segments under vacuum conditions. The temperature is raised under argon micro-positive pressure protection, and the mixture is kept at a constant temperature for refining, then cooled, discharged, and the surface slag is peeled off. The modified component is high-purity rubidium chloride.

2. A method for preparing a covering agent for gallium antimonide surface growth, characterized in that, The preparation method of the covering agent for gallium antimonide surface growth includes the following preparation steps: (1) Mix sodium chloride and potassium chloride evenly, add 0.005~0.015 times the total mass of rubidium chloride and mix evenly. Place the mixture in a sealed alumina ball mill jar and heat it at 10 ... -3 Ball milling under vacuum conditions for 10-20 minutes, then loading into a quartz boat with an alumina liner to obtain a material boat; (2) The quartz tube is ignited at 1000~1200℃ for 1~3h, placed in an alumina heat-insulating cup, the material boat is pushed into the bottom of the tube, the flange is sealed with double-layer fluororubber, and under vacuum conditions, it is dehydrated at low temperature for 1~2h, removed impurities at medium temperature for 50~70min, refined at high temperature for 3~4h, the bubbling is stopped, and it is kept at constant temperature for 30~50min to separate into layers. The temperature is lowered to 300~340℃, the vacuum system is restarted, and it is naturally cooled to 50~60℃. The vacuum pump is stopped, argon is charged to atmospheric pressure, the tube is opened, and the surface slag containing impurities is peeled off to obtain the surface covering agent for gallium antimonide growth.

3. The method for preparing the covering agent for gallium antimonide surface growth according to claim 2, characterized in that, The molar ratio of sodium chloride to potassium chloride in step (1) is 1:

1.

4. The method for preparing the covering agent for gallium antimonide surface growth according to claim 2, characterized in that, The process parameters for low-temperature dehydration in step (2) are as follows: under vacuum conditions, the temperature is increased to 300-400℃ at a rate of 1-2℃ / min, and calcined for 1-2 hours.

5. The method for preparing the covering agent for gallium antimonide surface growth according to claim 2, characterized in that, The process parameters for medium-temperature impurity removal in step (2) are as follows: heat up to 550-650℃ at a rate of 0.5-1.5℃ / min, close the vacuum valve, and burn for 50-70 minutes under argon protection at 0.01-0.03MPa.

6. The method for preparing the covering agent for gallium antimonide surface growth according to claim 2, characterized in that, The process parameters for high-temperature refining in step (2) are as follows: heating to 760-800℃ at a rate of 0.6-1℃ / min, using 2-4 min of ventilation and 4-6 min of standing, and refining for 3-4 h.

7. The method for preparing the covering agent for gallium antimonide surface growth according to claim 2, characterized in that, The process parameters for cooling to 300~340℃ in step (2) are: cooling to 300~340℃ at a rate of 0.5~0.7℃ / min under argon protection of 0.01~0.03MPa.

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