Preparation method of low-twin-line tellurium-cadmium compound single crystal based on moving heater method

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-line tellurium-cadmium compound single crystal based on a moving heater method. Directional seed crystals with specific crystallographic orientation, an alloy material and a polycrystal feeding material are sequentially arranged in the growth container from bottom to top, the directional seed crystals and the polycrystal feeding material are both Cd1-xZnxTe, and the alloy material is composed of Te and Cd1-xZnxTe pre-dissolved in the Te; a moving heater method is adopted, an alloy material is melted in an axial gradient temperature field to form a melting zone, and the melting zone is driven to directionally migrate through relative movement of a growth container and the temperature field, so that Cd1-xZnxTe is directionally crystallized and grown on a seed crystal. The method can effectively inhibit the formation of twin crystal lines, obtains the tellurium-cadmium compound single crystal with a complete structure and uniform components, and can be industrially used in the fields of high-performance radiation detection, medical imaging and the like.

Description

Technical Field

[0001] This invention belongs to the field of high-performance semiconductor crystal material preparation technology for radiation detection, specifically relating to a method for preparing low-twin cadmium telluride single crystals based on a moving heater method. Background Technology

[0002] Cd 1-x Zn x Te crystals, including cadmium telluride (CdTe, x=0) and cadmium zinc telluride (CZT, x>0), are important group II-VI compound semiconductor crystal materials and have irreplaceable application value in fields such as medical imaging and high-energy radiation detection. The moving heater method (THM) is currently one of the mainstream technologies for preparing cadmium telluride crystals. Compared with processes such as vertical gradient solidification (VGF) and vertical Bridgman (VB), its core advantages lie in its lower growth temperature, resulting in lower defect density and higher crystal purity. Furthermore, the THM method can optimize the uniformity of compositional distribution within the crystal by precisely controlling the movement of the molten zone, thus overcoming the compositional segregation problems that easily occur in VGF and VB methods. Therefore, it is widely used in the large-scale production of high-performance cadmium zinc telluride and cadmium telluride crystal materials.

[0003] Cadmium zinc telluride (CdZN) and cadmium telluride (CdTe) crystals possess suitable band gaps, excellent carrier mobility-lifetime products, and good X-ray and gamma-ray absorption coefficients. These unique physicochemical properties make them core materials for fields such as medical CT imaging, nuclear radiation monitoring, and astrophysical exploration. However, the growth process of these crystals is extremely sensitive to processing conditions and is easily affected by various factors, resulting in various defects that severely restrict their performance improvement and industrial application. Due to their face-centered cubic structure, atomic alignment deviations are prone to occur during crystal growth, leading to twin defects. The formation of twin lines disrupts the integrity of the crystal structure, obstructing carrier transport paths. Simultaneously, uneven temperature gradients and insufficient thermal stress release during crystal growth and cooling stages can easily induce internal cracks and grain boundaries, reducing the crystal's mechanical strength and electrical stability.

[0004] As fields such as medical imaging and high-energy radiation detection advance towards higher resolution and sensitivity, more stringent requirements are being placed on the structural integrity, compositional uniformity, and defect suppression capabilities of cadmium telluride single crystals. Existing fabrication methods based on the THM method and other processes result in an extremely high probability of twin lines forming, which conventional techniques struggle to suppress at the source. Twin lines not only directly disrupt the crystal lattice continuity, leading to a significant degradation in key electrical properties such as carrier mobility and lifetime, thus failing to meet the demands of high-end detection applications, but they also drastically reduce the proportion of intact, defect-free single-crystal blocks that can be separated during subsequent wafer-level processing such as cutting and grinding. A large number of ingots are discarded or downgraded due to twin line defects, causing a sharp increase in raw material, energy, and processing costs, severely limiting the industrial-scale widespread adoption of cadmium telluride crystals.

[0005] Given that existing technologies are unable to fundamentally suppress the initiation and expansion of twin line defects, leading to low success rates and high production costs in the preparation of large-size cadmium telluride single crystals, developing a technical solution that can specifically address the problem of frequent twin lines and ensure the integrity of the crystal structure and the stability of its performance has become a technical challenge that urgently needs to be tackled by those skilled in the art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing low-twin-line cadmium telluride single crystals based on a moving heater method. The purpose of this invention is to overcome the deficiencies of existing cadmium telluride single crystal preparation processes, such as high incidence of twin-line defects, low success rate of large-size single crystal preparation, and high production costs, thereby obtaining cadmium telluride single crystals with good structural integrity and stable performance, thus better meeting the industrial application needs in fields such as medical imaging and high-energy radiation detection.

[0007] This invention provides a method for preparing low-twin-line cadmium telluride single crystals based on a moving heater method. A directional seed crystal with a specific crystallographic orientation is placed at the bottom of a growth container. An alloy material is placed above the directional seed crystal, and a polycrystalline feed is placed above the alloy material. Using a moving heater method, the growth container is placed in a furnace cavity with an axial temperature gradient field. By moving the growth container relative to the temperature gradient field, the liquid molten zone formed by the melting of the alloy material is driven to migrate directionally relative to the growth container, thereby causing the cadmium telluride to crystallize directionally on the seed crystal and grow continuously. The directional seed crystal and the polycrystalline feed both have a Cd chemical composition. 1-x Zn x Te, an alloy material composed of Te and Cd 1-x Zn x Te composition, Cd in alloy materials 1-x Zn x Te is pre-dissolved in Te; where x∈[0,0.3].

[0008] As a further optimization of the above preparation method, the specific steps include: Step (1) Pre-synthesis of alloy material: Te raw material and Cd 1-x Zn x Te raw material is placed in a container, and the temperature is raised to melt Te and dissolve Cd. 1-x Zn x Te raw materials are used to form liquid alloys, which are then cooled and solidified into solid alloys. Step (2) Loading and sealing: In the growth container, the directional seed crystal, the alloy material obtained in step (1) and the polycrystalline feed are loaded from bottom to top, and then the growth container is vacuumed and sealed. Step (3) Temperature field establishment and crystal growth: The sealed growth container is placed in a temperature field with an axial temperature gradient, causing the alloy to heat up and melt to form an initial molten zone. Subsequently, the growth container or temperature field is driven to move relative to each other, causing Cd to grow. 1-x Zn x Te undergoes directional crystallization growth on the seed crystal; Step (4) Cooling and treatment: After growth, the temperature is gradually reduced to room temperature, and the residue at the end of the ingot is removed to obtain Cd. 1-x Zn x Te single crystal ingot.

[0009] As a further optimization of the above preparation method, the crystallographic orientation of the oriented seed crystal is as follows: <545> Crystal orientation.

[0010] As a further optimization of the above preparation method, the crystallographic orientation of the oriented seed crystal is as follows: <136> Crystal orientation.

[0011] As a further optimization of the above preparation method, in step (1), the Te raw material and Cd 1-x Zn x The liquid alloy formed by heating and mixing Te raw materials is an unsaturated liquid alloy.

[0012] As a further optimization of the above preparation method, in step (3), the established temperature field includes a high temperature zone at the top, a low temperature zone at the bottom, and a gradient temperature zone in the middle; wherein the temperature of the high temperature zone is set in the range of 900±50℃, the temperature of the low temperature zone is set in the range of 500±50℃, and the axial temperature gradient of the gradient temperature zone is set in the range of 15±3K / cm.

[0013] As a further optimization of the above preparation method, in step (3), by setting the initial axial position of the growth container in the furnace cavity, the initial melting zone is located at the junction of the directional seed crystal and the alloy material.

[0014] As a further optimization of the above preparation method, in step (3), the relative moving speed between the growth container and the temperature field is 2.5-6 mm / day, preferably 3-5 mm / day.

[0015] As a further optimization of the above preparation method, in step (3), after the temperature field is established and the set temperature is reached, the temperature is kept constant for 24-72 hours before crystal growth is carried out.

[0016] As a further optimization of the above preparation method, in step (4), the cooling rate of the programmed cooling is controlled within the range of 25±5℃ / day.

[0017] Beneficial effects This invention provides a method for preparing cadmium telluride (CdT) single crystals based on a moving heater, which effectively overcomes problems such as twinning defects, cracks, and grain boundaries that easily occur during the traditional CdT single crystal growth process, significantly improving the forming quality and structural integrity of the single crystal material. The prepared CdT single crystals possess uniform compositional distribution and excellent structural integrity, with no obvious defects, meeting the stringent performance requirements of wafer-level processing in high-end fields such as medical imaging and high-energy radiation detection. Furthermore, this preparation method features strong process stability and excellent controllability, providing a reliable path for the large-scale, high-quality preparation of high-performance CdT single crystals. Compared to traditional preparation techniques using conventional oriented seed crystals, it exhibits significant advantages in defect suppression, performance optimization, and application adaptability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the growth device.

[0019] Figure 2 This is a schematic diagram of the sealing crucible and its loading.

[0020] Figure 3 and Figure 4 This is a photograph of the CZT ingot grown in Example 1.

[0021] Figure 5 and Figure 6 This is a photograph of the CZT ingot grown in Example 2.

[0022] Figure 7 and Figure 8 This is a physical image of the CZT ingot grown in Comparative Example 1.

[0023] In the diagram, 1. Quartz base; 2. Heater; 3. Sealing crucible; 4. Directional seed crystal; 5. Alloy material; 6. Polycrystalline feed; 7. Sealing plug. Detailed Implementation

[0024] like Figure 1The diagram shows the main structure of the moving heater method (THM) crystal growth apparatus used in this invention. The quartz base 1 serves as a support component and is connected to the crucible descent drive device, enabling the sealed crucible 3 to move smoothly along the furnace axis. The heater 2 is arranged in a ring configuration and fixedly installed in the center of the furnace to create an axial temperature gradient field. The sealed crucible 3 is a sealed reaction vessel for crystal growth, filled with the raw materials used for crystal growth. It is positioned above the quartz base 1 and descends synchronously with it. During its movement, the material sequentially passes through high-temperature and low-temperature zones, driving the directional movement of the molten zone.

[0025] The sealing crucible 3 is a quartz crucible with an inner wall treated by carbonization, such as... Figure 2 As shown, the inside of the sealing crucible 3 is filled with materials in functional layers: the bottom layer is the directional seed crystal material area 4, which is used to place directional seed crystals, which serve as the nuclei for single crystal growth; the middle layer is the alloy material area 5, which is used to place pre-synthesized alloy materials, which are used to form the initial liquid melting zone; the upper layer is the polycrystalline feed area 6, which is used to fill polycrystalline feed materials, which serve as the solute supplement source for crystal growth; the top is vacuum sealed by the sealing plug 7, which evacuates the inside of the crucible to a high vacuum and then seals it, providing an oxygen-free and impurity-free sealed environment for crystal growth.

[0026] Based on the principle of the moving heater method, this device maintains a stable temperature gradient field through heater 2. When the sealing crucible 3 slowly descends with the quartz base 1, the molten zone inside the sealing crucible 3 moves axially under the drive of the temperature field gradient, causing the solute to precipitate directionally on the surface of the oriented seed crystal and grow into a single crystal. The polycrystalline feed gradually dissolves as the molten zone moves, continuously replenishing the solute and ensuring the continuous growth of the single crystal.

[0027] The present invention is further illustrated below with specific embodiments. These embodiments are exemplary and intended to illustrate the problem and explain the present invention, and are not intended to be limiting.

[0028] Example 1 Step S1: Raw material preparation Based on the sealing crucible 3 with a diameter of 75mm, a heating zone length of 60mm, and a growth temperature of 900℃, the material ratio was determined. The alloy material contained 700g of tellurium (Te) raw material and zinc-cadmium tellurium (CZT, Cd). 0.9 Zn 0.1 Te) raw material is 450g; polycrystalline feed (CZT, Cd) 0.9 Zn 0.1 The weight of Te is 2.5Kg.

[0029] Step S2: Pre-synthesis of unsaturated alloy material A quartz crucible with carbonized inner walls was selected as the container to prevent a chemical reaction between CZT and quartz. 700g of Te material determined in S1 and 450g of CZT raw material were placed together in the crucible and heated to 700℃. During this process, Te completely melted into a liquid solvent, while the CZT raw material did not reach its melting point but dissolved in the liquid Te, forming a liquid unsaturated alloy material with uniform composition. After the holding time was completed, the mixture was cooled to room temperature, and the liquid alloy material solidified into a solid alloy material.

[0030] Step S3: Oriented material loading and crucible sealing Prepare a 20mm high crystallographically oriented sample. <545> For the CZT oriented seed crystal, the following materials are loaded into the carbonized quartz crucible in the following order from bottom to top: (Bottom layer placed...) <545> A directional seed crystal is used, with S2 pre-synthesized solid alloy material placed in the middle layer, and solid polycrystalline CZT feed material loaded in the upper layer. After loading, the crucible is connected to a vacuum system and evacuated to a high vacuum of <10^-4 Pa to remove air. Then, the open end of the crucible is sealed with an oxyhydrogen flame to form a closed growth environment.

[0031] Step S4: Loading the growth furnace and setting temperature field parameters The sealed quartz crucible is carefully placed into the THM (Transient Heater Method) crystal growth furnace, with the bottom of the crucible positioned 15 mm below the high-temperature zone. This ensures that the top of the oriented seed crystal and the bottom of the alloy material are initially within the high-temperature zone of the furnace. The furnace temperature control system is activated, and the temperature parameters are set as follows: target temperature of 900℃ for the high-temperature zone, target temperature of 500℃ for the low-temperature zone, and axial temperature gradient control of 15 K / cm within the furnace. At this point, all materials within the crucible remain in a stratified solid state.

[0032] Step S5: Heating and isothermal control, and directional crystal growth The furnace heating program is initiated, and the temperature is uniformly increased to the set temperature at a rate of 30℃ / min. After reaching the set temperature, it is held at this temperature for 48 hours, during which the solid alloy material melts into a liquid molten zone in the high-temperature zone (Te is the solvent, and CZT is the solute). Subsequently, the crucible lowering device is activated, and the crucible is lowered at a slow rate of 3mm / day. The temperature gradient drives the liquid molten zone to move along the crucible axis. The CZT solute precipitates directionally on the seed crystal surface at the low-temperature end and crystallizes into a solid single crystal. The polycrystalline feed gradually dissolves in the liquid Te as the molten zone moves, continuously replenishing the solute to ensure continuous growth of the single crystal.

[0033] Step S6: Gradient cooling and finished product acquisition Once the liquid Te solvent has completely drained to the end of the ingot, the crystal growth process ends. A cooling program is then initiated, slowly lowering the temperature to room temperature at a rate of 25°C / day to prevent rapid cooling from causing thermal stress that could lead to crystal cracking or defects. During the cooling process, the liquid Te at the end gradually solidifies into a solid state, while the CZT single crystal maintains a stable crystal structure. Removing the Te material at the end yields a fully single-crystal CZT ingot.

[0034] Example 2 Step S1: Raw material preparation Based on the sealing crucible 3 with a diameter of 75mm, a heating zone length of 60mm, and a growth temperature of 900℃, the material ratio was determined. The alloy material contained 700g of tellurium (Te) raw material and zinc-cadmium tellurium (CZT, Cd). 0.9 Zn 0.1 Te) raw material is 450g; polycrystalline feed (CZT, Cd) 0.9 Zn 0.1 The weight of Te is 2.5Kg.

[0035] Step S2: Pre-synthesis of unsaturated alloy material A quartz crucible with carbonized inner walls was selected as the container to prevent a chemical reaction between CZT and quartz. 700g of Te material determined in S1 and 450g of CZT raw material were placed together in the crucible and heated to 700℃. During this process, Te completely melted into a liquid solvent, while the CZT raw material did not reach its melting point but dissolved in the liquid Te, forming a liquid unsaturated alloy material with uniform composition. After the holding time was completed, the mixture was cooled to room temperature, and the liquid alloy material solidified into a solid alloy material.

[0036] Step S3: Oriented material loading and crucible sealing Prepare a 20mm high crystallographically oriented sample. <136> For the CZT oriented seed crystal, the following materials are loaded into the carbonized quartz crucible in the following order from bottom to top: (Bottom layer placed...) <136> A directional seed crystal is used, with S2 pre-synthesized solid alloy material placed in the middle layer, and solid polycrystalline CZT feed material loaded in the upper layer. After loading, the crucible is connected to a vacuum system and evacuated to a high vacuum of <10^-4 Pa to remove air. Then, the open end of the crucible is sealed with an oxyhydrogen flame to form a closed growth environment.

[0037] Step S4: Loading the growth furnace and setting temperature field parameters The sealed quartz crucible is carefully placed into the THM (Transient Heater Method) crystal growth furnace, with the bottom of the crucible positioned 15 mm below the high-temperature zone. This ensures that the top of the oriented seed crystal and the bottom of the alloy material are initially within the high-temperature zone of the furnace. The furnace temperature control system is activated, and the temperature parameters are set as follows: target temperature of 900℃ for the high-temperature zone, target temperature of 500℃ for the low-temperature zone, and axial temperature gradient control of 15 K / cm within the furnace. At this point, all materials within the crucible remain in a stratified solid state.

[0038] Step S5: Heating and isothermal control, and directional crystal growth The furnace heating program is initiated, and the temperature is uniformly increased to the set temperature at a rate of 50℃ / min. After reaching the set temperature, it is held at this temperature for 48 hours, during which the solid alloy material melts into a liquid molten zone in the high-temperature zone (Te is the solvent, and CZT is the solute). Subsequently, the crucible lowering device is activated, and the crucible is lowered at a slow rate of 5mm / day. The temperature gradient drives the liquid molten zone to move along the crucible axis. The CZT solute precipitates directionally on the seed crystal surface at the low-temperature end and crystallizes into a solid single crystal. The polycrystalline feed gradually dissolves in the liquid Te as the molten zone moves, continuously replenishing the solute to ensure continuous growth of the single crystal.

[0039] Step S6: Gradient cooling and finished product acquisition Once the liquid Te solvent has completely drained to the end of the ingot, the crystal growth process ends. A cooling program is then initiated, slowly lowering the temperature to room temperature at a rate of 25°C / day to prevent rapid cooling from causing thermal stress that could lead to crystal cracking or defects. During the cooling process, the liquid Te at the end gradually solidifies into a solid state, while the CZT single crystal maintains a stable crystal structure. Removing the Te material at the end yields a fully single-crystal CZT ingot.

[0040] Comparative Example 1 Step S1: Raw material preparation Based on the sealing crucible 3 with a diameter of 75mm, a heating zone length of 60mm, and a growth temperature of 900℃, the material ratio was determined. The alloy material contained 700g of tellurium (Te) raw material and zinc-cadmium tellurium (CZT, Cd). 0.9 Zn 0.1 Te) raw material is 450g; polycrystalline feed (CZT, Cd) 0.9 Zn 0.1 The weight of Te is 2.5Kg.

[0041] Step S2: Pre-synthesis of unsaturated alloy material A quartz crucible with carbonized inner walls was selected as the container to prevent a chemical reaction between CZT and quartz. 700g of Te material determined in S1 and 450g of CZT raw material were placed together in the crucible and heated to 700℃. During this process, Te completely melted into a liquid solvent, while the CZT raw material did not reach its melting point but dissolved in the liquid Te, forming a liquid unsaturated alloy material with uniform composition. After the holding time was completed, the mixture was cooled to room temperature, and the liquid alloy material solidified into a solid alloy material.

[0042] Step S3: Oriented material loading and crucible sealing Prepare a 20mm high crystallographically oriented sample. <111> For the CZT oriented seed crystal, the following materials are loaded into the carbonized quartz crucible in the following order from bottom to top: (Bottom layer placed...) <111> A directional seed crystal is used, with S2 pre-synthesized solid alloy material placed in the middle layer, and solid polycrystalline CZT feed material loaded in the upper layer. After loading, the crucible is connected to a vacuum system and evacuated to a high vacuum of <10^-4 Pa to remove air. Then, the open end of the crucible is sealed with an oxyhydrogen flame to form a closed growth environment.

[0043] Step S4: Loading the growth furnace and setting temperature field parameters The sealed quartz crucible is carefully placed into the THM (Transient Heater Method) crystal growth furnace, with the bottom of the crucible positioned 15 mm below the high-temperature zone. This ensures that the top of the oriented seed crystal and the bottom of the alloy material are initially within the high-temperature zone of the furnace. The furnace temperature control system is activated, and the temperature parameters are set as follows: target temperature of 900℃ for the high-temperature zone, target temperature of 500℃ for the low-temperature zone, and axial temperature gradient control of 15 K / cm within the furnace. At this point, all materials within the crucible remain in a stratified solid state.

[0044] Step S5: Heating and isothermal control, and directional crystal growth The furnace heating program is initiated, and the temperature is uniformly increased to the set temperature at a rate of 30℃ / min. After reaching the set temperature, it is held at this temperature for 48 hours, during which the solid alloy material melts into a liquid molten zone in the high-temperature zone (Te is the solvent, and CZT is the solute). Subsequently, the crucible lowering device is activated, and the crucible is lowered at a slow rate of 3mm / day. The temperature gradient drives the liquid molten zone to move along the crucible axis. The CZT solute precipitates directionally on the seed crystal surface at the low-temperature end and crystallizes into a solid single crystal. The polycrystalline feed gradually dissolves in the liquid Te as the molten zone moves, continuously replenishing the solute to ensure continuous growth of the single crystal.

[0045] Step S6: Gradient cooling and finished product acquisition Once the liquid Te solvent has completely drained to the end of the ingot, the crystal growth process ends. A cooling program is then initiated, slowly lowering the temperature to room temperature at a rate of 25°C / day to prevent thermal stress from rapid cooling that could cause crystal cracking or defects. During the cooling process, the liquid Te at the end gradually solidifies. Removing the Te material at the end yields the CZT ingot.

[0046] Result characterization Figure 3 , Figure 4 The example shown is from Example 1. <545> The ingots obtained from seed crystal growth have a uniform and dense metallic luster on the cut surface, and there are no visible twin lines, cracks and grain boundary defects on the surface. Figure 5 , Figure 6 The example shown is from Example 2. <136> The ingots obtained from seed crystal growth also have no visible twin lines, cracks, or grain boundary defects. Figure 7, Figure 8 The example shown is Comparative Example 1. <111> The ingots obtained from seed crystal growth show multiple twin lines on the surface of the ingots, and the cross-section of the ingots exhibits a typical equilateral triangular morphology of twin lines.

[0047] In summary, this invention utilizes the moving heater method (THM) and employs a specific seed crystal orientation ( <545> , <136> High-performance CZT single-crystal materials were successfully prepared. The prepared crystals have a smooth, crack-free surface, no twin lines or small-angle grain boundaries on the cut cross-section, and excellent internal compositional homogeneity with no obvious defects. This preparation method discovered in this invention can effectively solve the problems of traditional methods. <111> The technical challenge of high twin defects in orientation seed crystal growth has been overcome, and the prepared CZT single crystal can meet the stringent requirements of wafer-level processing in fields such as medical imaging and high-energy radiation detection.

[0048] The above embodiments are exemplary and are intended to illustrate the technical concept and features of the present invention, so that those skilled in the art can understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing low-twinned cadmium telluride single crystals based on a moving heater, characterized in that, A directional seed crystal with a specific crystallographic orientation is placed at the bottom of the growth container. An alloy material is placed above the directional seed crystal, and a polycrystalline feed is placed above the alloy material. A moving heater method is used, placing the growth container in a furnace cavity with an axial temperature gradient field. By causing relative movement between the growth container and the temperature gradient field, the liquid molten zone formed by the melting of the alloy material is driven to migrate directionally relative to the growth container, thereby causing cadmium telluride to crystallize directionally on the seed crystal and grow continuously. The directional seed crystal and the polycrystalline feed both have the chemical composition of Cd. 1-x Zn x Te, the alloy material is composed of Te and Cd 1-x Zn x Te composition, Cd in alloy materials 1-x Zn x Te is pre-dissolved in Te; where x∈[0,0.3].

2. The preparation method according to claim 1, characterized in that, Includes the following steps: Step (1) Pre-synthesis of alloy material: Te raw material and Cd 1-x Zn x Te raw material is placed in a container, and the temperature is raised to melt Te and dissolve Cd. 1-x Zn x Te raw materials are used to form liquid alloys, which are then cooled and solidified into solid alloys. Step (2) Loading and sealing: In the growth container, the directional seed crystal, the alloy material obtained in step (1) and the polycrystalline feed are loaded from bottom to top, and then the growth container is vacuumed and sealed. Step (3) Temperature field establishment and crystal growth: The sealed growth container is placed in a temperature field with an axial temperature gradient, causing the alloy to heat up and melt to form an initial molten zone. Subsequently, the growth container or temperature field is driven to move relative to each other, causing Cd to grow. 1-x Zn x Te undergoes directional crystallization growth on the seed crystal; Step (4) Cooling and treatment: After growth, the temperature is gradually reduced to room temperature, and the residue at the end of the ingot is removed to obtain Cd. 1- x Zn x Te single crystal ingot.

3. The preparation method according to claim 2, characterized in that, The crystallographic orientation of the oriented seed crystal is as follows: <545> Crystal orientation.

4. The preparation method according to claim 2, characterized in that, The crystallographic orientation of the oriented seed crystal is as follows: <136> Crystal orientation.

5. The preparation method according to claim 4 or 5, characterized in that, In step (1), the Te raw material and Cd 1-x Zn x The liquid alloy formed by heating and mixing Te raw materials is an unsaturated liquid alloy.

6. The preparation method according to claim 5, characterized in that, In step (3), the established temperature field includes a high temperature zone at the top, a low temperature zone at the bottom, and a gradient temperature zone in the middle; wherein the high temperature zone is set to a temperature in the range of 900±50℃, the low temperature zone is set to a temperature in the range of 500±50℃, and the axial temperature gradient of the gradient temperature zone is set to a temperature in the range of 15±3K / cm.

7. The preparation method according to claim 5, characterized in that, In step (3), by setting the initial axial position of the growth container in the furnace cavity, the initial melting zone is located at the junction of the directional seed crystal and the alloy material.

8. The preparation method according to claim 5, characterized in that, In step (3), the relative movement speed between the growth container and the temperature field is 2.5-6 mm / day.

9. The preparation method according to claim 5, characterized in that, In step (3), after the temperature field is established and the set temperature is reached, the temperature is kept constant for 24-72 hours before crystal growth is carried out.

10. The preparation method according to claim 5, characterized in that, In step (4), the cooling rate of the programmed cooling is controlled within the range of 25±5℃ / day.

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