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CN-122013296-A - THM crystal growth device and method for preparing low-cracking-rate tellurium cadmium compound crystal

CN122013296ACN 122013296 ACN122013296 ACN 122013296ACN-122013296-A

Abstract

The invention belongs to the technical field of growing devices and preparation of tellurium-cadmium compound single crystals, and particularly relates to a THM crystal growing device and a method for preparing a tellurium-cadmium compound crystal with low cracking rate. The device comprises a furnace body, a furnace chamber heater, a lifting support capable of lifting and a driving device thereof. The top of the lifting support is provided with a support groove for supporting the quartz crucible, and the bottom of the lifting support is provided with a heating module comprising an upper heat insulation layer, a bottom support heater and a lower heat insulation layer. The preparation method comprises the steps of material filling, single crystal growth and cooperative cooling. Wherein, start the collet heater in coordination with the cooling stage, after making it heat up to match with the ingot bottom temperature, cool down with the furnace chamber heater synchronously. According to the invention, the bottom of the ingot is subjected to auxiliary heating and synchronous slow cooling in the cooling stage after the crystal growth is finished, so that the thermal stress accumulation at the bottom and in the ingot is effectively relieved, the crystal cracking is obviously inhibited, and the structural integrity and the yield of the tellurium-cadmium compound single crystal are improved.

Inventors

  • FANG YATING
  • GAO XUBIN

Assignees

  • 奕瑞光芯(上海)科技有限公司

Dates

Publication Date
20260512
Application Date
20260204

Claims (10)

  1. 1. A THM crystal growth device is characterized by comprising a furnace body, wherein a furnace chamber which is vertically arranged is arranged in the furnace body, a furnace chamber heater (2) is circumferentially arranged on the inner side of the furnace chamber, a lifting support (3) which can lift is arranged in the furnace chamber, a driving device which drives the lifting support (3) to lift vertically is connected to the bottom of the lifting support (3), a quartz crucible (1) which is used for containing crystal growth raw materials is carried on the top of the lifting support (3), a supporting groove (4) which is opened upwards is formed in the top of the lifting support (3), the contour of the inner wall of the supporting groove (4) is matched with the contour of the bottom of the quartz crucible (1), a flat heating module is arranged at the bottom of the supporting groove (4), and the heating module is electrically connected with an external temperature control system.
  2. 2. The THM crystal growth apparatus of claim 1, wherein the heating module comprises an upper heat insulating layer, a bottom support heater (6) and a lower heat insulating layer which are sequentially stacked from top to bottom, wherein the upper heat insulating layer and the lower heat insulating layer are heat-resistant heat insulation boards (5) capable of slowly transferring heat, the bottom support heater (6) is electrically connected with an external temperature control system, and is used for starting and heating to a preset value matched with the bottom temperature of an ingot in a cooling stage after crystal growth is finished, and then cooling synchronously with the furnace chamber heater (2).
  3. 3. The THM crystal growing apparatus of claim 2, wherein an external lead (7) is electrically connected to an end of the shoe heater (6), a support rod (8) is connected to a bottom of the lifting shoe (3), a channel through which the external lead (7) passes is provided inside the support rod (8), and the external lead (7) extends to an outside of the furnace body through the channel.
  4. 4. The THM crystal growth apparatus of claim 2, wherein the heat shield (5) is an aluminum silicate fiber plate.
  5. 5. A THM crystal growth apparatus according to any one of claims 2 to 4, wherein the depth of the bracket (4) is not less than 15mm.
  6. 6. The THM crystal growing apparatus of claim 5, wherein the base heater (6) is a heating wire tray body or a flat-plate electric heater formed by coiling high-temperature-resistant metal resistance wires and having a disc shape as a whole.
  7. 7. The THM crystal growth apparatus according to claim 5, wherein the inner wall of the quartz crucible (1) is treated with carbon vapor.
  8. 8. The THM crystal growing apparatus of claim 5, wherein the insulating plates (5) used for the upper and lower insulating layers have a thickness in the range of 5-25mm and a thermal conductivity in the range of 0.08-0.32W/(mK).
  9. 9. A method of preparing a low cracking rate cadmium telluride crystal using a THM crystal growth apparatus according to any one of claims 2 to 8, comprising the steps of: S1, preparing and filling materials, namely preparing raw materials required by growth of tellurium cadmium compound crystals, wherein the raw materials comprise an alloy material forming an initial melting zone and a polycrystal material serving as a solute source, the alloy material consists of tellurium (Te) solvent and tellurium cadmium compound solute, the polycrystal material is tellurium cadmium compound polycrystal material, the alloy material and the polycrystal material are filled into a quartz crucible (1) from bottom to top, and the quartz crucible (1) is vacuumized and packaged, wherein the chemical general formula of tellurium cadmium compound meets Cd 1-x Zn x Te, and x is more than or equal to 0 and less than or equal to 0.3; S2, growing single crystals, namely placing the packaged quartz crucible (1) in a bracket (4) of the lifting support (3), establishing an axial temperature gradient field in a furnace chamber through the furnace chamber heater (2), controlling the lifting support (3) to drive the quartz crucible (1) to move downwards at a preset speed, so that raw materials form a melting zone and move along the axial direction, and realizing the directional growth of the tellurium cadmium single crystals; s3, after the single crystal growth is finished, starting a bottom support heater (6) in the heating module in a cooling stage, controlling the temperature of the bottom support heater to be increased to a preset temperature matched with the temperature of the bottom of the ingot, and controlling the furnace chamber heater (2) and the bottom support heater (6) to synchronously cool to room temperature.
  10. 10. The method for producing a low cracking rate cadmium telluride crystal according to claim 9, wherein the process of cooperative cooling in step S3 is that the furnace chamber heater (2) is controlled to start cooling at a first cooling rate, the temperature field is kept constant when the temperature of the bottom of the ingot is reduced to a preset temperature within the range of 350-450 ℃, the susceptor heater (6) is started to heat at a preset heating rate so that the temperature of the region of the susceptor (4) reaches a target temperature consistent with the temperature of the bottom of the ingot, and then the furnace chamber heater (2) and the susceptor heater (6) are controlled to synchronously cool to room temperature at a second cooling rate, wherein the second cooling rate is equal to or slower than the first cooling rate.

Description

THM crystal growth device and method for preparing low-cracking-rate tellurium cadmium compound crystal Technical Field The invention belongs to the technical field of growing devices and preparation of tellurium-cadmium compound single crystals, and particularly relates to a THM crystal growing device and a method for preparing a tellurium-cadmium compound crystal with low cracking rate. Background The Cd 1-xZnx Te crystal is taken as an important semiconductor crystal material, and takes up an irreplaceable core position in high-end fields such as medical CT imaging, nuclear radiation monitoring, celestial body physical detection and the like by virtue of a proper forbidden band width, excellent carrier mobility-service life product and excellent X-ray and gamma-ray absorption coefficient, so that the Cd 1-xZnx Te crystal is a key for promoting the development of related fields to high-resolution and high-sensitivity directions. Among the numerous crystal growth methods, the moving heater method (THM method) is one of the mainstream technologies for the current mass production of cadmium telluride crystals. Compared with the crystal growth technologies such as a vertical gradient solidification method (VGF) and a vertical Bridgman method (VB), the growth temperature of the THM method is remarkably reduced, which is helpful for reducing thermal defects caused by high temperature, so that a crystal material with lower intrinsic point defect density and higher purity can be theoretically obtained. Meanwhile, the distribution uniformity of components in the crystal can be obviously optimized by precisely regulating and controlling the migration process of the melting zone, and the problem of component segregation easily occurring in the VGF method and the VB method is effectively solved, so that the method is widely applied to the industrial production of high-performance tellurium-zinc-cadmium and cadmium telluride crystals. Although the THM method has a plurality of advantages, the tellurium-cadmium compound crystal is of a face-centered cubic structure, the atomic arrangement is extremely sensitive to the conditions of the growth and post-treatment processes, various defects are easily generated due to the influence of various factors such as temperature field distribution, stress release and the like, and the improvement of the crystal performance and the landing of industrial application are seriously restricted. The cooling stage after the crystal growth is finished is a high-initiation link of crack initiation and propagation, the thermal conductivity of the tellurium cadmium compound crystal is low, the brittleness is strong, and defects such as crystal ingot bottom cracking, internal cracks, grain boundary propagation and the like are easily caused in the cooling stage. The defects not only can directly damage the integrity of a crystal structure, cause the blocking of a carrier transport path and obviously attenuate the electrical property and detection sensitivity of the crystal, but also can greatly reduce the yield of complete single crystal blocks of the crystal ingot in the subsequent wafer-level processing processes of cutting, grinding and the like, and a large number of crystal ingots are abandoned or degraded due to the defects of bottom cracking and the like, so that the raw materials, energy sources and processing cost are rapidly increased, and the large-scale popularization of tellurium-cadmium compound crystals in various fields is severely limited. In summary, although the existing THM crystal growth technology has advantages in principle, the existing THM crystal growth technology still suffers from problems of thermal stress induced cracking and the like when crystals of cadmium zinc telluride, cadmium telluride and the like are actually prepared, and the improvement of the structural integrity of the crystals, the improvement of the yield of products and the reduction of the production cost are limited. Disclosure of Invention Aiming at the defects existing in the prior art, the invention provides a THM crystal growth device and a method for preparing a tellurium cadmium compound crystal with low cracking rate. The invention aims to solve the technical problem that the cooling stage of the tellurium-cadmium compound crystal grown by the THM method is easy to crack, thereby providing a technical basis for realizing the reliable preparation of tellurium-cadmium compound single crystals with high quality and high yield. The invention provides a THM crystal growth device, which comprises a furnace body, wherein a furnace chamber is vertically arranged in the furnace body, a furnace chamber heater is circumferentially arranged on the inner side of the furnace chamber, a lifting support capable of lifting is arranged in the furnace chamber, the bottom of the lifting support is connected with a driving device for driving the lifting support to vertically lift, the top of the lifting suppo