456results about "Under a protective fluid" patented technology

The invention discloses a preparation device and method for growing a large-size silicon carbide single crystal. A raw material gas phase in a high-temperature area is transmitted to the surface of a seed crystal in a low-temperature area for crystal growth by using a physical gas phase transmission method; the device comprises a furnace chamber, a movable sectional type heating system, a thermal insulation material, a graphite crucible, porous graphite, a seed crystal unit, a crystal growth induction forming device and an electric field device. The method comprises the following steps: installing a seed crystal unit in a crucible filled with silicon carbide powder, placing the crucible in a heater, and carrying out a crystal growth stage to prepare the silicon carbide single crystal. The whole growth process of the crystal is in a constant temperature state, thermal stress caused by the temperature difference between the growth end and the seed crystal end and the temperature difference between the crystal edge and the crystal center in the top end seed crystal method crystal growth process is avoided, the dislocation defect of the crystal is reduced, and finally the high-quality silicon carbide single crystal is obtained. And the production cost is reduced.

The invention relates to the field of crystal preparation, in particular to a production device and a preparation method of monocrystalline silicon, the monocrystalline silicon and an insulated gate bipolar transistor. The apparatus for producing monocrystalline silicon comprises: a crucible for placing and melting a raw material; the heating module is arranged around the crucible and comprises a fixed heater at the upper part and a movable heater at the lower part, and the movable heater moves along the lifting direction of the crystal bar so as to accurately control the crystal growth temperature gradient and the oxygen diffusion transmission mode at different stages of crystal growth; and the magnetic field module is used for applying an asymmetric hook-shaped magnetic field in the crystal growth process so as to inhibit convection of raw materials in the crucible, reduce the oxygen concentration and improve the radial uniformity of oxygen. According to the technical scheme, on the basis of 300mm N-type monocrystalline silicon, under low oxygen (lt; 5ppma), ROGlt; and on the basis of 10%, the target of low potential type defect density can also be achieved, so that the high-quality requirements, including ultralow oxygen content, low defect density and the like, of an IGBT (Insulated Gate Bipolar Translator) on a silicon single crystal substrate are met. The efficient preparation of the ultralow-oxygen N-type silicon single crystal is realized by combining a heater with a novel structure with a CUSP magnetic field technology and matching with crystal pulling process parameter optimization. According to the silicon single crystal prepared by the method, the performance and the reliability of an IGBT (Insulated Gate Bipolar Translator) can be remarkably improved, the production cost is reduced, and the requirements of modern power electronic devices on high-performance silicon-based materials are met.

A flow guide tube apparatus for a single crystal furnace, a single crystal furnace and a single crystal silicon rod; the flow guide tube apparatus comprises a bottom surface that undulates in a wave-like manner along a radial direction, thereby guiding an inert gas in a manner that increases the flow rate of the inert gas.

The invention relates to the technical field of photovoltaic crystal growth, in particular to a method for improving the axial resistance uniformity of an antimony-doped silicon single crystal and the antimony-doped silicon single crystal. The method provided by the invention comprises the following steps: growing the antimony-doped silicon single crystal by adopting a czochralski method, and at an equal-diameter stage, controlling the furnace pressure to be 4-13torr; in the czochralski method, after leading and releasing are failed or growth of a single antimony-doped silicon single crystal is completed, supplemental doping of an antimony element is carried out according to the volatilization amount of the antimony element. In the method disclosed by the invention, the tail resistance and the head resistance of the prepared antimony-doped silicon single crystal are kept highly consistent by controlling the furnace pressure at the equal-diameter stage, regulating and controlling the volatilization rate of the antimony element, combining the segregation phenomenon of the antimony element in silicon and determining the supplementary doping time of the antimony element.

The invention relates to a preparation method of a silicon single crystal rod and a silicon wafer. Comprising a melting stage, a temperature adjusting stage, a welding stage, a seeding stage, a shouldering stage, an equal-diameter stage, an ending stage and a breaking stage which are carried out in sequence, in the equal-diameter stage, the pulling speed is controlled to be within a first pulling speed range, and the solid-liquid interface temperature gradient is controlled to be within a first gradient range; wherein the range of the first pulling speed ranges from 0.5 mm / min to 1.1 mm / min; the first gradient range is 3 DEG C / cm to 5 DEG C / cm. By reducing the temperature gradient of a solid-liquid interface and lowering the crystal pulling rate, the stability of a thermal field is enhanced, and sufficient conditions are provided for the composite reaction of Sii and V, so that the impurity capturing efficiency is improved, the internal purity of the crystal is improved, and the impurities are effectively removed.

The invention relates to the technical field of semiconductor material growth, and aims to solve the technical problems that the service life of a heating element is shortened due to single atmosphere sharing, the quality is difficult to guarantee due to many crystal defects, the single crystal production cost is high, and the production efficiency is low in the prior art. The invention discloses a single crystal growth device which is characterized by comprising a furnace body, a first chamber, a second chamber, a heating assembly, a growth assembly, an atmosphere isolation and heat conduction assembly, an atmosphere management system and a central control system, the atmosphere isolation and heat conduction assembly is used for separating the furnace body into a first cavity and a second cavity which are isolated in an airtight mode, and efficient heat transfer is achieved. By the adoption of the scheme, atmosphere structure separation and combined crucible design can be achieved, high quality and high purity of crystals are guaranteed, meanwhile, the service life of a heating element is effectively prolonged, and the operation cost is remarkably reduced.

The invention relates to the technical field of infrared optical materials, and particularly discloses a large-size high-resistance infrared silicon single crystal and a preparation method thereof. The doping concentration of cobalt oxide in the large-size high-resistance infrared silicon single crystal is 10 ppm to 100 ppm, and the atomic concentration of phosphorus in the large-size high-resistance infrared silicon single crystal is 2 * 10 < 13 > / cm < 3 > to 6 * 10 < 13 > / cm < 3 >. The oxide of transition metal cobalt and phosphorus impurities are doped into the infrared silicon single crystal, carriers of cobalt and phosphorus and carriers of impurities such as boron and oxygen generate a recombination effect, so that the concentration of free carriers in the silicon single crystal is reduced, and the absorption coefficient of the doped silicon single crystal is relatively small; the infrared transmittance of the silicon single crystal in a medium wave band can be obviously increased, the resistivity can reach 600 omega.cm or above, and the use requirement of the infrared silicon single crystal in a high-performance infrared optical system can be met.

The invention relates to a method for controlling the axial resistivity of a crystal bar and the crystal bar, and the method comprises the steps: carrying out the equal-diameter growth of a first crystal bar according to a preset equal-diameter parameter, measuring the axial resistivity of the first crystal bar, and drawing a change curve of the axial resistivity of the first crystal bar; calculating the unevenness of the axial resistivity of the first crystal bar; when the unevenness of the axial resistivity of the first crystal bar is greater than or equal to 17%, the evaporation of the antimony element is promoted or inhibited by adjusting the pressure parameter aiming at different change stages of the axial resistivity, so that the concentration of the antimony element in the silicon solution is adjusted; the risk that the reduction trend of the axial resistivity of the crystal bar is large due to the fact that the concentration of the antimony element in the silicon solution is high is reduced, and the risk that the increase trend of the axial resistivity of the crystal bar is large due to the fact that the concentration of the antimony element in the silicon solution is low is also reduced, namely, the difference value between the maximum resistivity and the minimum resistivity is reduced; and thus, the nonuniformity of the axial resistivity is reduced.

The invention provides a method for controlling the resistivity drop amplitude of a heavily doped single crystal, and relates to the technical field of heavily doped crystal pulling, in the crystal pulling process, after the curing rate, through common adjustment of the pulling speed, pressure and argon, a crystal bar with the resistivity drop amplitude being less than or equal to 0.4 m omega when the resistivity is below low resistance is pulled; wherein the pulling speed is kept unchanged, the change amplitude of unit pressure is 5Kpa / 100mm to 30Kpa / 100mm, and the change amplitude of unit argon is 10slm / 100mm to 40slm / 100mm, as the current process cannot directly obtain that the head resistance is low resistance, after a certain curing rate, when the resistivity of a crystal bar reaches low resistance, the pulling speed, the pressure and the argon are jointly adjusted, so that the qualification rate is improved, and the production cost is reduced. Meanwhile, the stability is improved, and the standard deviation is reduced (N is equal to 10).

The invention provides a silicon single crystal rod and a preparation method thereof, a silicon wafer and a solar cell, the silicon single crystal rod contains hydrogen element, the silicon single crystal rod has a center and an edge along the radial direction of the silicon single crystal rod, and (CH1-CH2) / CH2 is more than or equal to 0 and less than or equal to 35%; and the dislocation density of the silicon single crystal rod meets the condition that (rho1-rho2) / rho1 is greater than or equal to-80% and less than or equal to 80%. According to the silicon single crystal rod provided by the invention, the hydrogen element is doped, and the distribution uniformity of the hydrogen element in the radial direction of the silicon single crystal rod is controlled, so that the recombination effect of defects such as dislocation and vacancy on carriers is effectively reduced in the radial range of the whole silicon single crystal rod, the minority carrier lifetime is prolonged, meanwhile, the stress distribution in the silicon single crystal rod is improved, and the service life of the silicon single crystal rod is prolonged. And the stress is more uniformly released on the cross section of the whole silicon single crystal rod, so that the mechanical property of the silicon rod is enhanced.

The invention provides a nitrogen protection system for crystal pulling and an accurate flow control method thereof. The system comprises a nitrogen storage device, a first control valve, a second control valve, a third control valve and a control module, the control module is electrically connected with the first control valve, the second control valve and the third control valve. One end of the first control valve is connected with the nitrogen storage device, and the other end of the first control valve is connected with a first gas inlet formed in one side of the upper end of an auxiliary furnace chamber of the crystal pulling furnace; one end of the second control valve is connected with the nitrogen storage device, and the other end is connected with a second gas inlet formed in the furnace bottom of the main furnace chamber of the crystal pulling furnace; one end of the third control valve is connected with the nitrogen storage device, and the other end is connected with a third gas inlet formed in the upper end of one side of the main furnace chamber of the crystal pulling furnace. According to the nitrogen protection system for crystal pulling and the accurate flow control method of the nitrogen protection system, accurate control over protection gas for crystal pulling is achieved, and the quality of finished crystal pulling products is indirectly improved.

Provided is a GaAs wafer that can suitably be used to produce LiDAR sensors in particular and a method of producing a GaAs ingot that can be used to obtain such a GaAs wafer. The GaAs wafer has a silicon concentration of 5.0×1017 cm−3 or more and less than 3.5×1018 cm−3, an indium concentration of 3.0×1017 cm−3 or more and less than 3.0×1019 cm−3, and a boron concentration of 1.0×1018 cm−3 or more. The average dislocation density of the GaAs wafer is 1500 / cm2 or less.

The invention relates to the field of monocrystalline silicon preparation, particularly provides a monocrystalline silicon rod production method based on a czochralski method, and aims to solve the problem of how to improve the crystallization rate of monocrystalline silicon. In order to achieve the purpose, the single crystal silicon rod production method based on the czochralski method comprises the step of adjusting the flow / flow velocity of inert gas and the liquid opening distance from the lower edge of a guide cylinder to the liquid level of molten silicon in an equal-diameter growth stage based on the equal-diameter growth length of single crystals. On the basis of the equal-diameter growth length of single crystals, the flow / flow velocity of inert gas and the liquid opening distance from the lower edge of a guide cylinder to the liquid level of molten silicon are adjusted, so that the heat convection phenomenon between the inert gas and the molten silicon is controlled, the longitudinal temperature gradient in the single crystal furnace is further controlled, and sufficient heat dissipation capability in crystal growth is ensured; the heat released when the molten silicon is converted into the solid silicon is taken away in time, so that the necessary supercooling degree is formed on the interface of the molten silicon and the solid silicon, the single crystal has enough growth power to keep normal growth, and the crystal forming rate of the single crystal is improved.

The invention relates to a 4-inch low-dislocation indium antimonide lt; 211gt, 211gt; the invention discloses a preparation method of directional single crystals and belongs to the technical field of photoelectric materials. According to the method, a Czochralski method is adopted to grow the single crystal, a resistance furnace is arranged on the periphery of an induction coil of a heating device, and by accurately controlling heating conditions, designing a proper temperature field in a growth chamber and further combining growth conditions such as the state of a solid-liquid interface, the pulling speed, the rotating speed and particularly the shoulder expanding angle in the crystal growth process, the single crystal is obtained. The longitudinal temperature gradient in the crystal growth process is reduced, and the dislocation density of the large-size indium antimonide single crystal with the diameter of 4 inches can be obviously reduced, so that indium antimonide is enabled to be lt; 211gt, 211gt; the dislocation density of the directional single crystal is less than 100 / cm < 2 >.

The present application relates to the technical field of silicon carbide production and processing, and discloses a silicon carbide substrate having a stepwise stress distribution. The silicon carbide substrate comprises a first main surface and a second main surface; the first main surface is provided with a first gradient stress zone, a second gradient stress zone surrounding the first gradient stress zone, and a third gradient stress zone surrounding the second gradient stress zone, the width of the third gradient stress zone extending inwards from the edge of the substrate is 2.5-30 mm, and the width of the second gradient stress zone extending inwards from the edge of the third gradient stress zone is 10-50 mm; the relative internal stress of the first gradient stress zone is greater than or equal to the relative internal stress of the second gradient stress zone and smaller than the relative internal stress of the third gradient stress zone. The relative internal stresses of different zones of the silicon carbide substrate transition uniformly, and a stepwise distribution is realized, such that the quality of the silicon carbide substrate can be improved, and the use range of the silicon carbide substrate is expanded.

The invention provides a silicon single crystal rod and a preparation method thereof, a silicon wafer and a solar cell. The invention provides a silicon single crystal rod. The silicon single crystal rod contains a hydrogen element. The ratio of the resistivity of the head of the monocrystalline silicon rod to the resistivity of the tail of the monocrystalline silicon rod is 0.8-2.0; and the dislocation density of the silicon single crystal rod meets the condition that (rho1-rho2) / rho1 is greater than or equal to-80% and less than or equal to 80%. The silicon single crystal rod provided by the invention is doped with the hydrogen element, so that the distribution uniformity of the doped element in the silicon single crystal rod is improved, the internal defects of the silicon single crystal rod in the growth process are reduced, and the overall mechanical property and electrical property of the silicon single crystal rod are improved by controlling the distribution of the dislocation density of the silicon single crystal rod within a reasonable interval.

The invention discloses a control method of a single crystal furnace, the single crystal furnace comprises a crucible and a water cooling screen arranged above the crucible, the single crystal furnace further comprises a splash-proof device, the splash-proof device comprises a protective part and a suspender assembly, the control method comprises the following steps: connecting the upper end of the suspender assembly with a seed crystal rope of the single crystal furnace, and preliminarily matching the protective part with the lower end of the suspender assembly; the seed crystal rope is controlled to drive the suspender assembly to move downwards, so that the protection part is placed in the water cooling screen; controlling the protection part to be separated from the lower end of the suspender assembly, and controlling the seed crystal rope to drive the suspender assembly to move upwards; controlling to add a silicon material into the crucible; after material melting is finished, the seed crystal rope is controlled to drive the suspender assembly to move downwards; matching the protection piece with the lower end of the suspender assembly; controlling the seed crystal rope to drive the suspender assembly to move upwards, and taking out the protective part. The control method of the single crystal furnace is simple, normal use of the water cooling screen can be ensured, and the crystallization rate and production quality of single crystals are improved.

The invention discloses a device and a method for inhibiting crucible oxidation and raw material decomposition in gallium oxide single crystal growth, the device comprises a furnace body, an iraurita crucible, a thermal insulation layer, an induction coil, a lifting mechanism and the like, a temperature dynamic regulation and control system is arranged between the iraurita crucible and the thermal insulation layer; the temperature dynamic regulation and control system is used for monitoring the temperature distribution of the iridium crucible and the inner cavity in real time and regulating the heating frequency of the induction coil through feedback temperature; a melt decomposition monitoring system is arranged in the inner cavity close to the iraurita crucible and is used for detecting the gallium atom concentration and oxygen partial pressure change in the inner cavity in real time; and an atmosphere active adjusting system is also arranged in the furnace body. According to the device, the gallium oxide single crystal can be obtained, and the problems of crucible oxidation, melt decomposition and unstable crystal quality caused by a high-temperature environment can be solved; through dynamic monitoring and regulation, the oxidation and corrosion loss of the iraurita crucible is reduced, and meanwhile, the large-size and high-quality beta-Ga2O3 single crystal is obtained.

The invention relates to the technical field of single crystal drawing, in particular to a single crystal drawing system. The single crystal drawing system comprises a single crystal furnace, a nitrogen supply unit and an argon supply unit, the single crystal furnace comprises a main chamber and an auxiliary chamber, the main chamber is communicated with the auxiliary chamber through a throat, the upper end of the auxiliary chamber is communicated with a first gas inlet main pipe which is communicated with the nitrogen / argon supply unit, and the throat is communicated with a second gas inlet main pipe which is communicated with the nitrogen / argon supply unit. Therefore, nitrogen can be used for replacing argon to serve as inert gas shielding gas in all stages or part of stages of single crystal drawing, so that the production cost is reduced; meanwhile, the thermal conductivity of nitrogen is higher than that of argon, so that heat can be transferred more effectively, a thermal field in the furnace is more uniform, the crystal growth stability is improved, and the generation probability of crystal defects is reduced. Meanwhile, at the crystal pulling temperature, nitrogen can inhibit volatilization of impurities in silicon to a certain extent, so that the impurities in the crystal are distributed more uniformly, and the electrical property of the crystal can be accurately controlled.

The invention discloses a control method of a single crystal furnace, the single crystal furnace comprises a crucible and a water cooling screen arranged above the crucible, the single crystal furnace further comprises a splash-proof device, the splash-proof device comprises a protective part and a charging cylinder assembly, and the control method comprises the following steps: connecting the upper end of the charging cylinder assembly with a seed crystal rope of the single crystal furnace; the protection piece is preliminarily matched with the lower end of the feeding cylinder assembly; the seed crystal rope is controlled to drive the feeding cylinder assembly to move downwards, so that the protection part is placed in the water cooling screen; controlling the charging barrel assembly to add a silicon material into the crucible; after material melting is finished, the seed crystal rope is controlled to drive the feeding cylinder assembly to move upwards, and the protection part is taken out. The control method of the single crystal furnace is simple, normal use of the water cooling screen can be ensured, the crystal forming rate and the production quality of single crystals can be improved, the operation steps can be reduced, and the processing efficiency can be improved.

The invention discloses an edge-defined film-fed crystal growth method, which comprises: S1, placing a growth raw material in a crucible, placing a mold in the crucible, placing a seed crystal at a position 3-50 mm right above the mold through a seed crystal rod, the mold being provided with a curved surface inner cavity; s2, the upper heat preservation device and the middle heat preservation device are vacuumized and filled with inert gas; s3, performing exhaust treatment; s4, raising the temperature in the crucible to a first temperature, and melting the growth raw material in the crucible; s5, the seed crystal makes contact with the mold, the temperature is increased to a second temperature, and the seed crystal is pulled up; s6, reducing the diameter of the seed crystal, pulling the seed crystal for 5-10 mm, and cooling for the first time; s7, separating the crystal from the mold; and S8, annealing treatment is conducted after cooling. A uniform heating space is provided for growth of crystals, release of growth stress and thermal stress of the crystals is controlled, and impurities volatilized in the process of taking away the interior of the heat preservation device at high temperature are taken away through exhaust; the seed crystal is in contact with the curved-surface inner cavity of the mold to grow the curved-surface crystal, so that the cutting and rough machining cost is reduced.

The present application belongs to the technical field of production and processing of silicon carbides. Disclosed are a silicon carbide wafer with low lattice distortion, and a crystal. The silicon carbide wafer has a diameter of 150mm or more, and the silicon carbide wafer comprises a first main surface and a second main surface, wherein at any horizontal plane parallel to the first main surface and / or the second main surface, the radial comprehensive stress of the wafer is -30 MPa to 30 MPa, and the radial comprehensive stress is a stress value measured in a region that vertically extends from the first main surface or the second main surface into the wafer up to 1%-33% of the thickness of the wafer. The stress distribution of the silicon carbide wafer is uniform, and thus when the silicon carbide wafer is used as a substrate or a seed crystal, the residual stress in epitaxial wafers and crystals can be reduced, the genetic characteristics are optimized, and the yield is improved, thereby obtaining high-quality epitaxial wafers or crystals.

The present disclosure provides a single crystal silicon, a method for manufacturing the same, and a silicon wafer, the method comprising: when applying a magnetic field to a raw material melt and pulling up the single crystal silicon by a Czochralski method, growing the single crystal silicon in such a manner that the magnetic field intensity is controlled to 2000-3000 gauss. The silicon single crystal thus grown has an oxygen concentration of 5.6 ppma or more and 8.5 ppma or less, an RRG in a crystal cross-section orthogonal to the growth direction of the silicon single crystal of 1% or less, a low oxygen concentration, and high uniformity of radial resistance distribution.

The invention relates to a waste heat recovery method and device. The waste heat recovery method comprises the following steps that S1, argon is introduced into a crystal through a first pipeline in the growth process of the crystal in the single crystal furnace, argon introduction is stopped after crystal growth is completed, the single crystal furnace is externally connected with a cooling pipeline, a gas outlet of the single crystal furnace is further communicated with a thermoelectric power generation mechanism, and the thermoelectric power generation mechanism is electrically connected with an energy storage device; s2, cooling liquid is introduced into the cooling pipeline, the cooling liquid is vaporized into first gas with heat, and the first gas flows into the thermoelectric power generation mechanism; and S3, the thermoelectric power generation mechanism converts heat of the first gas into electric energy and stores the electric energy in the energy storage device. By means of the arrangement, waste heat recovery after the single crystal furnace is shut down is completed, and waste of heat energy is avoided.

A single crystal metal wire preparation device comprises a furnace body with a containing cavity, and a smelting crucible provided with a heater is arranged in the containing cavity; the extension pipe is vertically connected to the lower side of the smelting crucible, the upper end of the extension pipe communicates with the interior of the smelting crucible, and an outlet is formed in the lower end of the extension pipe; the cooling pipe is wound on the lower part of the extension pipe, and the cooling pipe is used for introducing cooling liquid to cool the lower part of the extension pipe; and the traction material receiving mechanism is used for downwards dragging the metal wires growing out of the outlet of the extension pipe. According to the scheme, a large cooling gradient is formed between the upper portion and the lower portion of the extension pipe, after metal raw material molten liquid in the smelting crucible downwards flows into the extension pipe, the metal raw material molten liquid is cooled and grows into a single crystal metal wire, and the single crystal metal wire is pulled out of an outlet of the extension pipe under the action of the traction material collecting mechanism and then wound; and the cooling growth process of the single crystal metal wire is mainly carried out in the extension pipe, so that the single crystal metal wire is not easy to break, the production and processing stability is good, and the yield is high.

The invention belongs to the technical field of semiconductor wafer manufacturing, and particularly relates to a method for growing a gallium oxide single crystal by a cold crucible method and a czochralski method, which comprises the following steps of: heating a gallium oxide raw material in a crucible at high frequency for the first time, keeping the temperature for a certain time, increasing the heating frequency to completely melt gallium oxide, and adjusting the pressure of cooling water to obtain the gallium oxide single crystal. The molten gallium oxide forms a gallium oxide solid layer on the inner wall of the crucible to isolate the contact between the gallium oxide at the center and the inner wall of the crucible, then crystal pulling is carried out, and the heating frequency is gradually reduced while crystal pulling is carried out. According to the technical scheme, through the design of the crucible structure and the adjustment of the heating frequency of the high-frequency heating device, a solid gallium oxide layer is formed between gallium oxide melt and the inner surface of the crucible in the crystal pulling process, the gallium oxide solid layer can completely isolate the contact between internal gallium oxide and a crucible body material, and the crystal pulling quality is improved. And the produced gallium oxide crystal is prevented from being polluted.

The utility model provides a quartz crucible assembly for indium antimonide crystal growth and a growth furnace. The quartz crucible assembly comprises a first quartz crucible and a second quartz crucible; the first quartz crucible is provided with an inner cavity with an upward opening and a closed bottom side and peripheral side; the second quartz crucible is in a big-end-down horn shape, is hollow inside, and is opened upwards and downwards; the first quartz crucible is configured to be used for containing an indium antimonide material for growing indium antimonide crystals by a czochralski method at the bottom of the inner cavity; the second quartz crucible is arranged in the first quartz crucible, is positioned on the indium antimonide material of the first quartz crucible and is in contact with the inner circumferential wall of the first quartz crucible at the bottom periphery; the height of the second quartz crucible is 1 / 3-6 / 7 of the height of the inner cavity of the first quartz crucible; the inner diameter of the bottom of the second quartz crucible is 1 / 2-3 / 5 of the inner diameter of the top of the inner cavity of the first quartz crucible; and the inner diameter of the top of the second quartz crucible is 1 / 10-1 / 5 of the inner diameter of the top of the inner cavity of the first quartz crucible.

The present invention relates to a method for growing SiC crystals by a low-temperature solution method, and belongs to the technical field of crystal growth. After high-purity silicon, metal Fe or Cr, and rare earth metals are mixed and alloyed and smelted, the smelting time is 5-30min to obtain a Si-Me-RE alloy with uniform composition; the Si-Me-RE alloy is loaded into a high-purity dense graphite crucible or a SiC crucible in a crystal growth furnace, and the melting temperature is kept above 1823K for at least 1 hour, so that C or SiC is dissolved in the high-temperature melt to obtain a SiC-saturated Si-Me-RE-C melt; the SiC-saturated Si-Me-RE-C melt is subjected to solution method growth of SiC single crystals or polycrystalline SiC. The method for growing SiC crystals by a low-temperature solution method provided by the present invention solves the problem of low solubility of C or SiC when growing SiC crystals by a solution method, and can greatly increase the solubility of C or SiC in the Si melt at low temperature (at least 400K lower than the existing PVT method), and is a method for growing SiC crystals with low energy consumption, low cost, high efficiency, and no pollution.

The present application discloses a silicon carbide substrate with a stepped stress distribution, belonging to the field of silicon carbide production and processing technology. The silicon carbide substrate includes a first main surface and a second main surface; the first main surface has a first gradient stress interval, a second gradient stress interval surrounding the first gradient stress interval, and a third gradient stress interval surrounding the second gradient stress interval, the width of the third gradient stress interval extending inward from the edge of the substrate is 2.5-30mm, and the width of the second gradient stress interval extending inward from the edge of the third gradient stress interval is 10-50mm; the relative stress in the body of the first gradient stress interval is greater than or equal to the relative stress in the body of the second gradient stress interval, and less than the relative stress in the body of the third gradient stress interval. The relative stress in the body of each area of ​​the silicon carbide substrate is uniformly transitioned and is distributed in a stepped manner, which can improve the quality of the silicon carbide substrate and expand the scope of use of the silicon carbide substrate.

The utility model discloses a temperature gradient regulation and control device for large-size germanium single crystal growth, and belongs to the technical field of germanium crystal growth. The device comprises a furnace body, a guide cylinder, a heat preservation cylinder, a ventilation ring and a graphite crucible, the furnace body comprises a main chamber and an auxiliary chamber, and the auxiliary chamber is arranged at the top of the main chamber; the ventilation ring is a tubular metal circular ring, the circular ring is hollow, the inner diameter of the circular ring is larger than the equal diameter of growing germanium single crystals, a plurality of air outlets are evenly formed in the inner wall and the outer wall of the circular ring, an air inlet is formed in the top face of the circular ring, and the ventilation ring is installed on the upper portion of the inner side of the guide cylinder and tightly attached to the guide cylinder or installed on the upper portion of the outer side of the guide cylinder and tightly attached to the guide cylinder. Low-temperature protective gas is blown to the flow guide cylinder through the ventilation ring, so that the temperature of the flow guide cylinder is reduced, the low-temperature flow guide cylinder serves as a cold end, crystallization latent heat, especially crystallization latent heat in the shouldering stage, transmission of crystallization latent heat radiation during shouldering is accelerated, the shouldering probability of growing large-size germanium single crystals is increased, and the purpose that the large-size germanium single crystals enter the equal-diameter stage through shouldering is smoothly achieved.