Preparation method of tellurium-zinc-cadmium crystal for improving uniformity of Zn component and product of tellurium-zinc-cadmium crystal

Abstract

The invention belongs to the field of semiconductor materials, and particularly discloses a preparation method of a cadmium zinc telluride crystal capable of improving the uniformity of a Zn component and a product of the cadmium zinc telluride crystal. The preparation method comprises the following steps: sequentially filling a seed crystal, a low-zinc polycrystalline ingot, a medium-zinc polycrystalline ingot and a high-zinc polycrystalline ingot into a single crystal tube from bottom to top, sealing the single crystal tube, and maintaining a vacuum state in the single crystal tube; and gradually heating the single crystal tube from the bottom of the equal-diameter section of the single crystal tube from bottom to top until the polycrystal above the melting zone is completely melted, stopping heating, cooling the polycrystal tube, and taking out the cadmium zinc telluride crystal. In the tellurium-zinc-cadmium single crystal rod prepared by the preparation method provided by the invention, the uniformity of the Zn content at the bottom is higher, and the equal-diameter part of the single crystal rod conforms to the Zn content range required by the national standard, so that the yield of a product can be remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor materials and relates to a zinc cadmium telluride crystal material, specifically to a method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity and the product thereof. Background Technology

[0002] In the field of infrared detection, cadmium telluride crystals play an irreplaceable role. Due to their extremely high sensitivity to infrared light, they can accurately detect changes in the infrared wavelength. Based on this characteristic, they are widely used in military night vision equipment, aerospace remote sensing instruments, and civilian security monitoring systems, providing reliable assurance for target detection, identification, and tracking. Furthermore, in the field of electronic information, the unique electrical and optical properties of cadmium telluride crystals make them an ideal material for manufacturing high-performance sensors, optoelectronic devices, and high-speed integrated circuits, powerfully driving the miniaturization and intelligentization of electronic devices.

[0003] Cadmium zinc telluride (Cd) 1-x Zn x Depending on its X value, Zn has different uses, but the segregation coefficient k0 of Zn in CdTe is about 1.16~1.35. This characteristic makes it easier for Zn to enter the solid phase during solid-liquid equilibrium. As the crystal grows, it continues to accumulate at the front of the solid phase, directly causing a decreasing gradient of axial composition. The typical Zn composition deviation Δx is 0.02~0.05, and the radial deviation will also be 0.01~0.03 due to the difference in the solidification rate at the interface.

[0004] The mainstream technical routes for traditional high-temperature melt directional solidification processes are the vertical Bridgman method and the vertical temperature gradient solidification method. Both processes share the same core growth logic: the polycrystalline ingot is heated sequentially from bottom to top until it melts. Then, using the seed crystal at the bottom of the crucible as the solidification starting point, single crystals are directionally grown along the axial direction. However, these processes have inherent temperature field defects. The growth environment needs to be maintained at a high temperature of 800–1000°C, and the temperature field distribution within the furnace cavity is uneven. A temperature gradient of 5–20 K / cm exists along the axial direction (the direction of single crystal growth); a temperature gradient of 2–5 K / cm exists along the radial direction (the cross-section of the crucible, from the center to the furnace wall). Furthermore, due to heater power drift and thermal convection disturbances, temperature fluctuations of ±1–3 K may occur in the target isothermal region.

[0005] These temperature field issues directly prevent the solid-liquid interface from maintaining an ideal planar state, thereby altering the solidification propagation rate of the interface and disrupting the stability of the zinc segregation coefficient k0. The combined effect of these multiple factors ultimately results in a lattice constant deviation Δa of 0.001–0.003 Å for the grown crystal rod. This not only fails to meet the stringent requirement of a zinc content uniformity deviation of <±0.005 Å for substrates used in infrared detectors, but also causes the product yield to drop significantly from over 80% in the ideal state to 30%–50%. Summary of the Invention

[0006] In view of the defects and deficiencies of the existing technology, the present invention provides, firstly, a method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity; secondly, the present invention provides zinc cadmium telluride crystals.

[0007] In a first aspect, the present invention provides a method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity, comprising the following steps: Step 1: Fill the shoulder section of the single crystal tube with seed crystals, and then load the low-zinc polycrystalline ingot, medium-zinc polycrystalline ingot and high-zinc polycrystalline ingot into the single crystal tube from bottom to top, seal the single crystal tube and maintain a vacuum state inside the single crystal tube. Step 2: Gradually heat the single crystal tube from bottom to top, starting from the bottom of the equal-diameter section, until the polycrystalline material above the melting zone has completely melted. Then stop heating, cool the polycrystalline tube, and remove the zinc cadmium telluride crystal.

[0008] Preferably, the general formula for low-zinc polycrystalline ingots is Cd. x Zn y Te, x+y=1, 0.06≤y≤0.065; the general formula for medium-zinc polycrystalline ingots is Cd z Zn f Te, z+f=1, 0.078≤f≤0.082; the general formula for high-zinc polycrystalline ingots is Cd m Zn n Te, m+n=1, 0.098≤n≤0.102.

[0009] More preferably, 0.018≤fy≤0.022; 0.018≤nf≤0.022.

[0010] Preferably, the mass ratio of low-zinc polycrystalline ingots, medium-zinc polycrystalline ingots, and high-zinc polycrystalline ingots in the single crystal tube is 1:1~2:4~5.

[0011] Preferably, the heating temperature is 1100~1130℃. After heating the low-zinc polycrystalline ingot at the bottom of the polycrystalline tube for 24~36 hours, the heating zone is slowly moved upward from the bottom of the polycrystalline tube at a speed of 3~6 mm / day.

[0012] Preferably, the cooling rate when cooling the polycrystalline tube is 30~50℃ / h.

[0013] Secondly, the present invention provides a zinc cadmium telluride crystal, which is prepared by the above-described preparation method.

[0014] Preferably, the Zn content in the isodiameter portion of the cadmium zinc telluride crystal is 0.096~0.104 at%.

[0015] Compared with the prior art, the present invention has the following significant advantages: In existing technologies, the preparation of cadmium zinc telluride (CZD) single crystal rods typically employs a high-temperature melt directional solidification process. This process is prone to zinc migration, where zinc deposits downwards along the axial direction of the single crystal ingot. Consequently, the zinc content in the bottom region of the final single crystal rod is significantly higher than that in the top region, resulting in a significantly lower zinc content. The CZD single crystal rod prepared by the method provided in this invention exhibits higher uniformity of Zn content at the bottom, and the uniform diameter portions of the single crystal rod all meet the Zn content range required by national standards, significantly improving product yield. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a single crystal tube filled with polycrystalline material in step 2 of Example 1; Figure 2 This is a schematic diagram of the combined structure of the single crystal tube and the single crystal furnace in step 3 of Example 1; Figure 3 This is a schematic diagram of the heater rising process of the single crystal furnace in step 3 of Example 1; Figure 4 This is a schematic diagram of the structure of a slice of cadmium zinc telluride crystal. Detailed Implementation

[0017] The present invention provides the following specific technical solutions.

[0018] In a first aspect, the present invention provides a method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity, comprising the following steps: Step 1: Fill the shoulder section of the single crystal tube with seed crystals, and then load the low-zinc polycrystalline ingot, medium-zinc polycrystalline ingot and high-zinc polycrystalline ingot into the single crystal tube from bottom to top, seal the single crystal tube and maintain a vacuum state inside the single crystal tube. Step 2: Gradually heat the single crystal tube from bottom to top, starting from the bottom of the equal-diameter section, until the polycrystalline material above the melting zone has completely melted. Then stop heating, cool the polycrystalline tube, and remove the zinc cadmium telluride crystal.

[0019] The inventors discovered that by pre-setting the Zn composition gradient of the polycrystalline ingot, the Zn concentration deviation caused by segregation can be reversed. Simultaneously, by combining this with directional heating and solidification melt zone control, overall homogenization of the Zn composition along the crystal rod's axis can be achieved. Three types of polycrystalline ingots—low-zinc, medium-zinc, and high-zinc—are pre-prepared and loaded in the order of "low-zinc at the bottom, medium-zinc in the middle, and high-zinc at the top," forming an initial composition gradient opposite to the segregation effect. When heated and melted from the bottom up, the low-zinc polycrystalline ingot melts first, corresponding to the solidification region at the bottom of the crystal rod, and the high-zinc polycrystalline ingot corresponds to the solidification region at the top of the crystal rod; during crystallization, k... o The segregation effect of >1 will enrich Zn in the bottom region and deplete Zn in the top region, which will just cancel out the preset initial gradient, and eventually make the Zn composition of the entire crystal rod tend to be uniform.

[0020] The process employs a bottom-up, gradual heating method, which creates a stable unidirectional melting zone. This avoids melt convection turbulence caused by simultaneous melting of multiple regions, reducing local deviations in radial Zn concentration. Simultaneously, the melting zone only covers a portion of the polycrystalline material, and heating is stopped immediately after melting. This rapidly fixes the solid-liquid interface morphology, preventing Zn segregation fluctuations caused by temperature variations or changes in interface migration rates, further ensuring the uniformity of Zn composition in both the axial and radial directions. Furthermore, the vacuum-sealed single-crystal tube environment suppresses Cd volatilization, maintains a stable melt stoichiometry, and prevents Zn segregation behavior from being indirectly affected by component imbalances, providing a stable thermodynamic environment for uniform crystallization.

[0021] The method for preparing Zn-uniform zinc cadmium telluride crystals provided by this invention comprises the following steps: Step 1: Prepare low-zinc, medium-zinc, and high-zinc polycrystalline ingots. Fill the shoulder section of the single-crystal tube with seed crystals. Then, sequentially load the low-zinc, medium-zinc, and high-zinc polycrystalline ingots into the single-crystal tube from bottom to top. Finally, use an oxyhydrogen flame to seal the single-crystal tube and the quartz bubble, maintaining a vacuum state inside the quartz tube. Figure 1 .

[0022] Step 2, load the single crystal tube into the single crystal furnace, such as... Figure 2 Then, the single crystal furnace is run, and the heater is heated to 1100~1130℃ at a heating rate of 30~50℃ / h. The low-zinc polycrystalline ingot area at the bottom of the single crystal furnace is then held for 24~36 hours.

[0023] Step 3: Control the heater to rise at a rate of 3-6 mm / day. As the heater rises, crystals continuously solidify below the molten zone, while polycrystalline material continuously melts above the molten zone to replenish it, such as... Figure 3 .

[0024] Step 4: Stop raising the heater once the polycrystalline material above the melting zone has completely melted. Turn off the heater and cool the single crystal tube to room temperature at a rate of 30-50°C / h. Then remove the single crystal tube, break it, and extract the cadmium zinc telluride crystal.

[0025] Through research, the inventors discovered that the temperature range of 1100~1130℃ satisfies the requirement for complete melting of cadmium zinc telluride polycrystalline ingots while avoiding excessive volatilization of Cd and Te caused by excessively high temperatures. At this temperature, the Cd vapor pressure can be stabilized within a controllable range, and the thermodynamic equilibrium of the solid-liquid interface is maintained, ensuring the segregation coefficient k of Zn. o It should be kept stable within a reasonable range of 1.16 to 1.35 to prevent the segregation behavior from becoming disordered due to temperature fluctuations.

[0026] Low-speed directional propulsion of 3~6 mm / day can form a smooth and stable solid-liquid interface, reducing the impact of interface migration rate fluctuations on Zn segregation. This allows the preset low-medium-high zinc polycrystalline ingot gradient to accurately offset the compositional deviation caused by segregation. At the same time, low-speed growth can reduce melt convection disturbance and avoid radial Zn concentration inhomogeneity. Ultimately, the axial and radial Zn compositional deviations of the crystal rod are controlled within ±0.004, significantly improving the yield and performance consistency of the crystal.

[0027] A cooling rate of 30~50℃ / h effectively alleviates thermal stress during the cooling process, preventing structural defects such as microcracks and dislocations from forming inside the crystal. This significantly improves the mechanical strength and lattice integrity of the crystal, providing a solid foundation for the fabrication of high-performance infrared detectors. Simultaneously, it maintains the thermodynamic equilibrium of Zn segregation at the solid-liquid interface during the later stages of solidification. The uniform Zn distribution formed by the pre-designed gradient polycrystalline ingot reduces the possibility of local Zn segregation, ensuring that the axial and radial Zn composition deviations of the crystal rod are controlled within ±0.004. Furthermore, this rate balances production efficiency and crystal quality, neither extending the process cycle nor disrupting the stoichiometry, achieving a dual balance between product yield and mass production adaptability.

[0028] In practical applications, the molar ratio of Cd:Zn:Te used in the seed crystals is 0.9:0.1:1. When the polycrystalline ingot is melted into a single crystal, only a very small amount of seed crystals (the seed crystals in contact with the polycrystalline ingot) will melt due to heat conduction. In the subsequent finished single crystal ingot, the shoulder section (the seed crystal part) needs to be removed. The seed crystal only plays the role of crystal introduction. That is, in practical applications, the seed crystal does not affect the distribution of Zn elements in the single crystal ingot.

[0029] Preferably, the general formula for low-zinc polycrystalline ingots is Cd. x Zn y Te, x+y=1, 0.06≤y≤0.065; the general formula for medium-zinc polycrystalline ingots is Cd z Zn fTe, z+f=1, 0.078≤f≤0.082; the general formula for high-zinc polycrystalline ingots is Cd m Zn n Te, m+n=1, 0.098≤n≤0.102.

[0030] The inventors discovered that by limiting the variation of Zn in different ranges for low, medium, and high zinc polycrystalline ingots, and by specifying the stoichiometric ratios of x+y=1, z+f=1, and m+n=1, the segregation characteristics of Zn in CdTe can be precisely matched, achieving directional compensation for the axial Zn distribution of the crystal rod. In high-zinc polycrystalline ingots, zinc segregates downwards, resulting in a final single-crystal ingot with a Zn content below 0.01 in the tail section. Figure 4 The tail section of the single crystal ingot is usually cut into other processes for reuse, and the tail section is not part of the final product.

[0031] More preferably, 0.018≤fy≤0.022; 0.018≤nf≤0.022.

[0032] Through research, the inventors discovered that by limiting the Zn content difference in different ranges of low, medium, and high zinc polycrystalline ingots to the above-mentioned preferred range, it can be ensured that the Zn content in the constant diameter portion of the final single crystal ingot is uniformly distributed.

[0033] Preferably, the mass ratio of low-zinc polycrystalline ingots, medium-zinc polycrystalline ingots, and high-zinc polycrystalline ingots in the single crystal tube is 1:1~2:4~5.

[0034] The inventors discovered that the filling quality of low-zinc polycrystalline ingots is determined by the height of the heating zone in the single-crystal furnace. The height of the ingot within the single-crystal tube must match the heating zone design to ensure that the low-zinc polycrystalline ingot is completely melted before crystal growth begins, while the medium-zinc and high-zinc polycrystalline ingots remain unmelted, laying the foundation for subsequent gradient control of zinc content. During crystal growth, the medium-zinc polycrystalline ingot gradually melts as the process progresses. Under the aforementioned optimized ratio, the melting rate of the medium-zinc polycrystalline ingot matches the zinc consumption rate in the melting zone, ensuring a continuous supply of adequate zinc while preventing the high-zinc polycrystalline ingot from prematurely participating in the melting process. The high-zinc polycrystalline ingot acts as a zinc content balancing unit. When the melting zone advances to the high-zinc polycrystalline ingot region, the dynamic matching of zinc content during its melting and crystal precipitation processes allows the system to quickly reach a stable zinc content state. Overall, the synergistic ratio of low-zinc polycrystalline ingots and medium-zinc polycrystalline ingots can achieve a smooth transition of zinc content in the first half of crystal growth. Combined with the balancing effect of high-zinc polycrystalline ingots, the uniformity of zinc content in the entire crystal growth process can be achieved.

[0035] In practical applications, commonly used single-crystal tubes (diameter of 1 to 8 inches) can all be used to prepare cadmium zinc telluride crystals using the technical solution provided by this invention.

[0036] Secondly, the present invention provides a zinc cadmium telluride crystal, which is prepared by the above-described method, wherein the Zn element content of the isodiameter portion of the zinc cadmium telluride crystal is 0.096~0.104 at%.

[0037] The constant diameter portions of the zinc cadmium telluride crystals prepared by this invention all meet the requirements of the national standard GB / T 39123-2020 "Specification for Zinc Cadmium Telluride Single Crystal Materials for X-ray and Gamma Ray Detectors" for Zn content of 0.096≤Zn≤0.104.

[0038] To make the technical problems, technical solutions and technical advantages of the present invention clearer, a detailed description will be given below with reference to specific examples. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0039] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0040] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0041] The specifications of the single crystal tube used in specific embodiments 1-3 and comparative example 1 of this invention are as follows: inner diameter is 3 inches, length is 500 mm, shoulder section height is 60 mm, equal diameter section height is 240 mm, and tail section height is 40 mm; the molar ratio of Cd:Zn:Te used in the seed crystal is 0.9:0.1:1.

[0042] Example 1: A method for preparing Zn-uniform zinc cadmium telluride crystals includes the following steps: Step 1: Prepare high-zinc polycrystalline ingots with a Cd:Zn:Te molar ratio of 0.9:0.1:1, medium-zinc polycrystalline ingots with a Cd:Zn:Te molar ratio of 0.92:0.08:1, and low-zinc polycrystalline ingots with a Cd:Zn:Te molar ratio of 0.94:0.06:1.

[0043] Step 2: Remove the single crystal tube, fill the shoulder section of the single crystal tube with the seed crystal, and then sequentially load 1061.5g low-zinc polycrystalline ingot, 1061.5g medium-zinc polycrystalline ingot and 5307.6g high-zinc polycrystalline ingot into the single crystal tube from bottom to top.

[0044] Step 3: Load the single crystal tube into the single crystal furnace and run the furnace. Heat the heater to 1120℃ at a rate of 40℃ / h. Keep the heating zone of the heater in the low-zinc polycrystalline ingot zone of the single crystal tube for 30 hours. Then, control the heater to start rising at a rate of 5mm / day. As the heater rises, crystals continuously solidify below the molten zone, while polycrystalline material continuously melts above the molten zone to replenish it.

[0045] Step 4: Stop the heater from rising until the polycrystalline material above the melting zone has melted completely. Then, control the single crystal furnace to cool down to room temperature at a rate of 40℃ / h. Remove the single crystal tube and break it to extract the zinc cadmium telluride crystal.

[0046] Figure 1 This is a schematic diagram of a single crystal tube filled with polycrystalline material in step 2 of Example 1.

[0047] Figure 2 This is a schematic diagram of the combined structure of the single crystal tube and the single crystal furnace in step 3 of Example 1.

[0048] Figure 3 This is a schematic diagram of the heater rising process of the single crystal furnace in step 3 of Example 1.

[0049] Comparative Example 1: A method for preparing Zn-uniform zinc cadmium telluride crystals includes the following steps: Step 1: Prepare a polycrystalline ingot with a Cd:Zn:Te molar ratio of 0.9:0.1:1.

[0050] Step 2: Remove the single crystal tube, fill the shoulder section of the single crystal tube with the seed crystal, and then load the 7430.7g polycrystalline ingot into the single crystal tube.

[0051] Step 3: Load the single crystal tube into the single crystal furnace and run the furnace. Heat the heater to 1120℃ at a rate of 40℃ / h. Keep the heating zone of the heater in the low-zinc polycrystalline ingot zone of the single crystal tube for 30 hours. Then, control the heater to start rising at a rate of 5mm / day. As the heater rises, crystals continuously solidify below the molten zone, while polycrystalline material continuously melts above the molten zone to replenish it.

[0052] Step 4: Stop the heater from rising until the polycrystalline material above the melting zone has melted completely. Then, control the single crystal furnace to cool down to room temperature at a rate of 40℃ / h. Remove the single crystal tube and break it to extract the zinc cadmium telluride crystal.

[0053] Example 2: A method for preparing Zn-uniform zinc cadmium telluride crystals includes the following steps: Step 1: Prepare high-zinc polycrystalline ingots with a Cd:Zn:Te molar ratio of 0.9:0.1:1, medium-zinc polycrystalline ingots with a Cd:Zn:Te molar ratio of 0.918:0.082:1, and low-zinc polycrystalline ingots with a Cd:Zn:Te molar ratio of 0.935:0.065:1.

[0054] Step 2: Remove the single crystal tube, fill the shoulder section of the single crystal tube with the seed crystal, and then sequentially load 1061.5g of low-zinc polycrystalline ingot, 2123.1g of medium-zinc polycrystalline ingot, and 4246.1g of high-zinc polycrystalline ingot into the single crystal tube from bottom to top.

[0055] Step 3: Load the single crystal tube into the single crystal furnace and run the furnace. Heat the heater to 1100℃ at a rate of 30℃ / h. Maintain the heating zone of the heater within the low-zinc polycrystalline ingot zone of the single crystal tube for 36 hours. Then, control the heater to begin rising at a rate of 3mm / day. As the heater rises, crystals continuously solidify below the molten zone, while polycrystalline material continuously melts above the molten zone to replenish it.

[0056] Step 4: Stop the heater from rising until the polycrystalline material above the melting zone has melted completely. Then, control the single crystal furnace to cool down to room temperature at a rate of 30℃ / h. Remove the single crystal tube and break it to extract the zinc cadmium telluride crystal.

[0057] Example 3: A method for preparing Zn-uniform zinc cadmium telluride crystals includes the following steps: Step 1: Prepare high-zinc polycrystalline ingots with a Cd:Zn:Te molar ratio of 0.90:0.10:1, medium-zinc polycrystalline ingots with a Cd:Zn:Te molar ratio of 0.922:0.078:1, and low-zinc polycrystalline ingots with a Cd:Zn:Te molar ratio of 0.94:0.06:1.

[0058] Step 2: Remove the single crystal tube, fill the shoulder section of the single crystal tube with the seed crystal, and then sequentially load 1061.5g of low-zinc polycrystalline ingot, 1592.3g of medium-zinc polycrystalline ingot, and 4776.9g of high-zinc polycrystalline ingot into the single crystal tube from bottom to top.

[0059] Step 3: Load the single crystal tube into the single crystal furnace and run the furnace. Heat the heater to 1130℃ at a rate of 50℃ / h, keeping the heating zone of the heater within the low-zinc polycrystalline ingot zone of the single crystal tube for 24 hours. Then, control the heater to begin rising at a rate of 6mm / day. As the heater rises, crystals continuously solidify below the molten zone, while polycrystalline material continuously melts above the molten zone to replenish it.

[0060] Step 4: Stop the heater from rising until the polycrystalline material above the melting zone has melted completely. Then, control the single crystal furnace to cool down to room temperature at a rate of 50℃ / h. Remove the single crystal tube and break it to extract the zinc cadmium telluride crystal.

[0061] The distribution of Zn element in the cadmium zinc telluride crystals prepared in Examples 1-3 and Comparative Example 1 was tested. First, the shoulder and tail sections of the cadmium zinc telluride crystals prepared in Examples 1-3 and Comparative Example 1 were removed, leaving only single crystals. Then, 2mm thick circular slices were taken at 20mm intervals from bottom to top and polished on both sides. After slicing, thin circular slices (the slices in the scribed part) were taken and numbered from bottom to top as follows: CZT-0, CZT-20, CZT-40, CZT-60, CZT-80, CZT-100, CZT-120, CZT-140, CZT-160, CZT-180, CZT-200, CZT-220, and CZT-240. Figure 4 This is a schematic diagram of the structure of a slice of cadmium zinc telluride crystal.

[0062] After double-sided polishing, the Zn content at the center of the obtained disc was measured by XRD extrapolation. The results are shown in Table 1 below, where represents the Zn content.

[0063] Table 1. Zn content of discs at different locations in Examples 1-3 and Comparative Example 1 The qualification of the CZT-0 to CZT-240 wafer samples was determined by referring to the Zn content requirements (0.096≤Zn≤0.104) in the national standard GB / T 39123-2020 Specification for Cadmium Zinc Telluride Single Crystal Materials for X-ray and Gamma Ray Detectors.

[0064] As shown in Table 1, the Zn content of all wafers (CZT-0 to CZT-240) in Examples 1-3 falls within the national standard acceptable range of 0.096-0.104. Specifically, the Zn content of Example 1 fluctuates between 0.098 and 0.102, Example 2 between 0.098 and 0.104, and Example 3 between 0.096 and 0.102. The difference in zinc concentration among the three is only 0.004-0.006, demonstrating extremely low Zn content. The Zn element distribution uniformity is excellent, while the Zn content of the initial segments (CZT-0, CZT-20, CZT-40) of Comparative Example 1 is 0.135, 0.122, and 0.110, respectively, all far exceeding the national standard upper limit. The zinc concentration difference reaches 0.037, which is significantly higher than that of the Example. It is not until CZT-100 that it gradually falls back to the qualified range, which fully proves that the formulation scheme of the present invention can effectively achieve precise control and uniform distribution of Zn content in the entire segment of cadmium zinc telluride crystal.

[0065] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope of the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity, characterized in that, Includes the following steps: Step 1: Fill the shoulder section of the single crystal tube with seed crystals, and then load the low-zinc polycrystalline ingot, medium-zinc polycrystalline ingot and high-zinc polycrystalline ingot into the single crystal tube from bottom to top, seal the single crystal tube and maintain a vacuum state inside the single crystal tube. Step 2: Gradually heat the single crystal tube from bottom to top, starting from the bottom of the equal-diameter section, until the polycrystalline material above the melting zone has completely melted. Then stop heating, cool the polycrystalline tube, and remove the cadmium zinc telluride crystal.

2. The method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity as described in claim 1, characterized in that, The general formula for low-zinc polycrystalline ingots is Cd. x Zn y Te, x+y=1, 0.06≤y≤0.065; the general formula for medium-zinc polycrystalline ingots is Cd z Zn f Te, z+f=1, 0.078≤f≤0.082; the general formula for high-zinc polycrystalline ingots is Cd m Zn n Te, m+n=1, 0.098≤n≤0.

102.

3. The method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity as described in claim 2, characterized in that, 0.018≤fy≤0.022;0.018≤nf≤0.022; 4. The method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity as described in claim 1, characterized in that, The mass ratio of low-zinc polycrystalline ingots, medium-zinc polycrystalline ingots, and high-zinc polycrystalline ingots in a single crystal tube is 1:1~2:4~5.

5. The method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity as described in claim 1 or 2, characterized in that, The heating temperature is 1100~1130℃. After heating the low-zinc polycrystalline ingot at the bottom of the polycrystalline tube for 24~36 hours, the heating zone is slowly moved upward from the bottom of the polycrystalline tube at a speed of 3~6 mm / day.

6. The method for preparing zinc cadmium telluride crystals with improved Zn composition uniformity as described in claim 1, characterized in that, The cooling rate for cooling polycrystalline tubes is 30~50℃ / h.

7. A zinc cadmium telluride crystal with uniform Zn composition, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 6.

8. The zinc cadmium telluride crystal with uniform Zn composition as described in claim 7, characterized in that, The Zn content in the constant-diameter portion of the cadmium zinc telluride crystal is 0.096~0.104 at%.

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