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CN-122013295-A - Preparation method of low twin line cadmium telluride single crystal based on mobile heater method

CN122013295ACN 122013295 ACN122013295 ACN 122013295ACN-122013295-A

Abstract

The invention belongs to the technical field of preparation of semiconductor crystal materials for high-performance radiation detection, and particularly relates to a preparation method of a low twin crystal line tellurium cadmium compound monocrystal based on a moving heater method. The method comprises the steps of sequentially arranging directional seed crystals, alloy materials and polycrystalline feeding materials with specific crystallographic orientations in a growth container from bottom to top, wherein the directional seed crystals and the polycrystalline feeding materials are Cd 1‑x Zn x Te, the alloy materials consist of Te and Cd 1‑x Zn x Te pre-dissolved in the alloy materials, melting the alloy materials in an axial gradient temperature field to form a melting zone by adopting a moving heater method, and driving the melting zone to directionally migrate through the relative movement of the growth container and the temperature field so as to lead Cd 1‑x Zn x Te to directionally crystallize and grow on the seed crystals. The invention can effectively inhibit the formation of twin lines, obtain tellurium-cadmium compound single crystals with complete structure and uniform components, and can be industrially used in the fields of high-performance radiation detection, medical imaging and the like.

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 preparation method of a low twin crystal line tellurium cadmium single crystal based on a moving heater method is characterized in that a directional seed crystal with specific crystallographic orientation is arranged at the bottom of a growth container, an alloy material is placed above the directional seed crystal, polycrystalline feeding is placed above the alloy material, the growth container is placed in a furnace chamber with an axial gradient temperature field by adopting the moving heater method, a liquid melting zone formed by melting the alloy material is driven to directionally migrate relative to the growth container by enabling the growth container and the gradient temperature field to do relative motion, so that tellurium cadmium is directionally crystallized and continuously grown on the seed crystal, the chemical compositions of the directional seed crystal and the polycrystalline feeding are Cd 1-x Zn x Te, the alloy material consists of Te and Cd 1-x Zn x Te, cd 1-x Zn x Te in the alloy material is pre-dissolved in Te, and x is 0, 0.3.
  2. 2. The method of manufacturing according to claim 1, comprising the steps of: The step (1) of alloy material pre-synthesis, which is to put Te raw material and Cd 1-x Zn x Te raw material into a container, heat up to melt Te and dissolve Cd 1-x Zn x Te raw material to form liquid alloy material, and then cool and solidify the liquid alloy material into solid alloy material; Charging and sealing, namely sequentially charging directional seed crystals, the alloy material obtained in the step (1) and polycrystalline feeding from bottom to top in a growth container, and then vacuumizing and sealing the growth container; setting up a temperature field and growing crystals, namely placing the sealed growth container in the temperature field with axial temperature gradient, heating and melting the alloy material to form an initial melting area, and then driving the growth container or the temperature field to move relatively to enable Cd 1-x Zn x Te to grow in a directional crystallization mode on the seed crystal; And (4) cooling and treating, namely, after the growth is finished, cooling to room temperature by a program, and cutting off residues at the tail end of the ingot to obtain the Cd 1- x Zn x Te single crystal ingot.
  3. 3. The method of claim 2, wherein the oriented seed crystal has a crystallographic orientation of <545> crystal orientation.
  4. 4. The method of claim 2, wherein the oriented seed crystal has a crystallographic orientation of <136> crystal orientation.
  5. 5. The method according to claim 4 or 5, wherein in the step (1), the liquid alloy material formed by heating and mixing the Te raw material and the Cd 1-x Zn x Te raw material is an unsaturated liquid alloy material.
  6. 6. The method according to claim 5, wherein in the step (3), the established temperature field comprises a high temperature region located at the upper side, a low temperature region located at the lower side and a gradient temperature region located at the middle, wherein the set temperature of the high temperature region is within 900+ -50 ℃, the set temperature of the low temperature region is within 500+ -50 ℃, and the set axial temperature gradient of the gradient temperature region is within 15+ -3K/cm.
  7. 7. The method according to claim 5, wherein in the step (3), the initial melting zone is located at the interface between the directional seed crystal and the alloy material by setting the initial axial position of the growth container in the furnace chamber.
  8. 8. The method according to claim 5, wherein the relative movement speed between the growth vessel and the temperature field in the step (3) is 2.5 to 6 mm/day.
  9. 9. The method according to claim 5, wherein in the step (3), after the temperature field is established and the set temperature is reached, the temperature is maintained for 24 to 72 hours and then crystal growth is performed.
  10. 10. The method according to claim 5, wherein in the step (4), the cooling rate of the program cooling is controlled within a range of 25.+ -. 5 ℃ per day.

Description

Preparation method of low twin line cadmium telluride single crystal based on mobile heater method Technical Field The invention belongs to the technical field of preparation of semiconductor crystal materials for high-performance radiation detection, and particularly relates to a preparation method of a low twin crystal line tellurium cadmium compound monocrystal based on a moving heater method. Background The Cd 1-xZnx Te crystal is used as an important II-VI compound semiconductor crystal material, comprises cadmium telluride (CdTe, x=0) and cadmium zinc telluride (CZT, x > 0), and has irreplaceable application value in the fields of medical imaging, high-energy radiation detection and the like. The moving heater method (THM) is one of the main technologies for preparing tellurium-cadmium compound crystals at present, and has the core advantages that compared with the vertical gradient solidification method (VGF), the vertical bridgman method (VB) and other processes, the growth temperature is lower, and lower defect density and higher crystal purity can be obtained. Meanwhile, the THM method can optimize the component distribution uniformity in the crystal by precisely regulating and controlling the movement process of the melting zone, is superior to the component segregation problem easily occurring in the crystal grown by the VGF method and the VB method, and is widely applied to the large-scale production of high-performance tellurium-zinc-cadmium and tellurium-cadmium crystal materials. Cadmium zinc telluride and cadmium telluride crystals have proper forbidden band width, excellent carrier mobility-service life product and good X-ray and gamma-ray absorption coefficients, and the unique physicochemical characteristics enable the cadmium zinc telluride and cadmium telluride crystals to be core materials in the fields of medical CT imaging, nuclear radiation monitoring, celestial body physical detection and the like. However, the growth process of the crystal is extremely sensitive to process conditions, is easily influenced by various factors to generate various defects, and severely restricts the performance improvement and the industrialized application of the crystal. Because the crystal is of a face-centered cubic structure, orientation deviation is easy to occur in the arrangement of atoms in the crystal growth process, twin crystal defects are further formed, the integrity of the crystal structure is damaged due to the generation of twin crystal lines, and a carrier transport path is blocked. With the development of the fields of medical imaging, high-energy radiation detection and the like towards high resolution and high sensitivity, more stringent requirements are put on the structural integrity, the component uniformity and the defect inhibition capability of the tellurium-cadmium single crystal. In the existing preparation scheme based on the THM method and other processes, the generation probability of twin crystal lines is extremely high, and the formation of twin crystal lines is difficult to be restrained from root to root by conventional technical means. The twin crystal line can not only directly destroy the lattice continuity of the crystal, so that the key electrical properties such as carrier mobility, service life and the like are obviously attenuated, but also can not meet the use requirement of a high-end detection scene, the twin crystal line can greatly reduce the ratio of the complete defect-free single crystal blocks which can be separated out in the subsequent wafer-level processing processes such as cutting, grinding and the like, and a large number of ingots are abandoned or degraded due to the twin crystal line defects, so that the raw materials, energy sources and processing cost are rapidly increased, and the industrialized popularization of tellurium cadmium compound crystals is severely limited. In view of the technical bottlenecks that the existing technical means are difficult to radically inhibit the initiation and the expansion of twin crystal line defects, so that the preparation success rate of large-size tellurium cadmium compound single crystals is low, the production cost is high, and the like, the technical scheme capable of pertinently solving the problem of high twin crystal line and guaranteeing the structural integrity and the performance stability of the crystals is developed, and the technical scheme becomes a technical problem to be overcome by the current technical personnel in the field. Disclosure of Invention Aiming at the defects existing in the prior art, the invention provides a preparation method of a low twin line tellurium cadmium compound monocrystal based on a moving heater method. The invention aims to overcome the defects of high occurrence of twin line defects, low success rate of large-size single crystal preparation and high production cost in the existing preparation process of tellurium-cadmium single crystals, and obtain the te