1. A preparation method of a low-defect cadmium zinc telluride crystal is characterized by comprising the following steps:

A. ingredients

Weighing high-purity raw materials Te, Cd and Zn according to a stoichiometric ratio in a hundred-grade ultra-clean room, mixing the raw materials, filling the mixture into a synthetic quartz crucible coated with a carbon film, vacuumizing, and sealing and sintering a quartz tube;

B. synthesis of

Putting the vacuum sealed quartz crucible into a special synthetic furnace for chemical combination reaction;

C. pipe replacement

Taking the synthesized cadmium zinc telluride polycrystal out of the quartz crucible in a hectorite ultra-clean room, putting the cadmium zinc telluride polycrystal and seed crystals into a pBN crucible, putting a Cd source with certain mass into a Cd partial pressure container of a quartz ampoule, putting the cadmium zinc telluride material and the pBN crucible together into the quartz ampoule with the Cd partial pressure container, vacuumizing, sealing and sintering;

D. charging furnace

Putting the sealed and sintered quartz ampoule into a non-isometric crystal growth furnace; in order to meet the requirements of a crystal growth furnace and an actual process, a quartz ampoule is fixed on a crystal growth crucible support in the crystal growth furnace;

E. crystal growth

Inputting the relevant crystal growth temperature and time into a temperature controller (12) according to the requirement of the tellurium-zinc-cadmium crystal growth temperature field; during the period, the accurate control of different temperatures of different parts is required, the movement of a solid-liquid interface of crystal growth is realized through the slow movement of a temperature field, and the tellurium-zinc-cadmium material is required to be incapable of moving in the whole crystal growth process;

F. temperature reduction

And after the crystal growth is finished, cooling the tellurium-zinc-cadmium crystal by 5-10 ℃/h until the temperature is room temperature, and finishing the crystal preparation.

2. The preparation method according to claim 1, wherein the B. synthesis specifically comprises:

putting a vacuum sealed quartz crucible into a special synthesis furnace, heating the synthesis furnace at 10 ℃/h, melting a Te simple substance into liquid when the temperature is raised to the melting point of Te, mixing the Te simple substance with a Cd solution, and carrying out violent combination reaction on the Te simple substance and the Cd solution; in order to ensure that the reaction is sufficient, the temperature of the synthesis furnace is kept at the temperature for 10-15 hours, so that the combination reaction between the raw materials is more sufficient;

and then, continuously heating the synthesis furnace to about 800 ℃, so that the elementary substances which are not fully subjected to the chemical combination reaction and are wrapped by the tellurium-zinc-cadmium are broken through the wrapping, further performing the chemical combination reaction, and cooling the tellurium-zinc-cadmium polycrystal to room temperature after the chemical combination reaction is finished.

3. The production method according to claim 1 or 2, characterized in that:

in the step of crystal growth, the temperature gradient is required to be more than or equal to 30 ℃/cm during the whole crystal growth period;

the Cd partial pressure of the tellurium-zinc-cadmium crystal can be represented by a formula log₁₀And (3) obtaining the Cd source by-5960.2/K +4.7191, wherein P is atm, and the temperature of the Cd source is controlled to be 700-900 ℃ according to experience and experimental feedback.

4. The production method according to claim 1 or 2, characterized in that:

the purity of the raw materials Te, Cd and Zn is more than or equal to 7N.

5. A preparation device for realizing the preparation method of low-defect cadmium zinc telluride crystal as defined in any one of claims 1 to 4, comprising a crystal growth furnace (2), a power supply control cabinet (1) and a crystal growth ampoule (3) provided with a Cd partial pressure vessel, characterized in that: the upper end and the lower end of the crystal growth furnace (2) are provided with sealing plugs (4), and the middle of the crystal growth furnace is provided with a furnace shell (11);

a furnace body heating area formed by piling up heating units (6) with different sizes and a heat insulation board (8) is sequentially arranged in the furnace shell (11) from top to bottom, and each heating unit (6) is provided with an electrode and a cable (10) which are respectively communicated with the power supply control cabinet (1);

temperature control thermocouples and temperature measurement thermocouples (7) are arranged in different areas, the thermocouples (7) are connected with a temperature controller (12) on the power control cabinet (1) through signal wires (13), and related crystal growth control parameters are arranged in the temperature controller (12);

the crystal growth furnace (2) also comprises a support frame (9) of the crystal growth ampoule (3) and a crystal growth ceramic furnace tube (14); a crystal growth pBN crucible (5) is also arranged in the crystal growth ampoule (3).

6. The manufacturing apparatus according to claim 5, wherein:

the crystal growth ampoule (3) is additionally provided with a Cd partial pressure container, and the temperature of the Cd partial pressure container is controlled to compensate the stoichiometric segregation caused by Cd partial pressure in the crystal growth process in real time;

the temperature controller (12) is provided with a temperature alarm, and when a furnace wire or a couple (7) of the heating unit (6) is broken, the alarm sends out an alarm signal.

7. The manufacturing apparatus according to claim 5, wherein:

the crystal growth furnace (2) is a non-equal-diameter cylindrical crystal growth furnace, and the furnace shell (11) is in a non-equal-diameter cylindrical shape with a large upper part and a small lower part.

8. The manufacturing apparatus according to claim 5, wherein:

the crystal growth furnace (2) comprises not less than 10 sections of independent heating units (6).

9. The manufacturing apparatus according to claim 8, characterized in that:

the heating units (6) are separated by a heat insulation plate (8).

10. The manufacturing apparatus according to claim 9, characterized in that:

the size of the heating unit (6) from top to bottom is reduced, the size of the upper end is 200mm, and the diameter of the lower end is 140 mm.

Background

The cadmium zinc telluride crystal is an excellent X-ray and gamma-ray detection material, has a high absorption coefficient for rays, can ensure detection sensitivity, has smaller detection units, still has high detection capability under the condition of being close to room temperature, and is one of the most potential materials in the field of high-performance ray detection.

In addition, the lattice constant of the tellurium-zinc-cadmium crystal can be modulated by components, so that the perfect matching with the tellurium-cadmium-mercury lattice of the high-performance infrared focal plane detector material is realized, and the tellurium-cadmium-mercury crystal is a preferable substrate material for growing a high-quality tellurium-cadmium-mercury film. Therefore, the preparation of high-quality and low-defect cadmium zinc telluride crystals is very important.

Because of the physical characteristics of high growth temperature, low thermal conductivity, small stacking fault energy, low critical shear stress and the like, the tellurium-zinc-cadmium crystal has the defects of difficult acquisition of tellurium-zinc-cadmium single crystals with high quality, large area and uniform components, and poor preparation repeatability. In order to obtain low-defect cadmium zinc telluride single crystal, research is carried out on various crystal growth methods at home and abroad, for example, the U.S. SELEX company adopts the horizontal Bridgman method (HB) to grow cadmium zinc telluride single crystal to obtain 5 x 10 EPD⁴cm^-2The tellurium-zinc-cadmium crystal has low repeatability. RVS company in the United states of America adopted the modified vertical Bridgman method (VB) to obtain 50X 50cm²Size (211) B telluriumAnd (3) carrying out LW/MW two-color HgCdTe growth verification on a zinc-cadmium substrate by adopting MBE. However, in the process of growth, the method generates mechanical movement, disturbance and creeping motion to the crystal growth due to the existence of mechanical relative motion, so that the temperature field of the crystal growth is unstable, and the growing solid-liquid interface is easily interfered. Energy and Nikko Materials company in Japan adopts a vertical Bridgman method (VGF) to realize the distribution of a temperature field through a multi-section crystal growth furnace, thereby thoroughly avoiding the influence of mechanical burning on the growth of the cadmium zinc telluride crystal and obtaining the cadmium zinc telluride single crystal with the size of 5 inches. In addition, in the aspect of preparing the cadmium zinc telluride crystal, a gas phase method, a microgravity method, a moving heating zone method and the like are also available. The above methods have various characteristics, and although each method has certain practicability, the fluctuation of a growing solid-liquid interface inevitably exists in the process of growing the tellurium-zinc-cadmium crystal by the vertical Bridgman method (VB), so that the quality of the crystal is reduced, and the number of defects is increased; in the traditional process of preparing the cadmium zinc telluride crystal by the vertical Bridgman method (VGF), the gradient of the temperature field is small due to the limited structure of the furnace body, and the requirement of preparing the high-quality cadmium zinc telluride crystal cannot be met.

Disclosure of Invention

The technical problem to be solved by the invention is as follows:

a low defect cadmium zinc telluride crystal growth device and method are provided through the fusion improvement of the traditional Bridgman method (VB) and the traditional vertical Bridgman method (VGF).

The overall thought of the invention is as follows:

a method and a device for preparing low-defect tellurium-zinc-cadmium crystals. The preparation device is a non-equal-diameter multi-section crystal growth furnace, a furnace body is provided with at least 10 sections of heating units, the heating units are separated by heat insulation plates, and the non-equal-diameter cylindrical furnace body structure can realize accurate control of different temperatures of different parts in the crystal preparation process. The device can lead the material to be always fixed in the middle of the hearth in the preparation process, avoid the movement of machinery and provide an ideal solid-liquid interface form and a vibration-free growth environment for the growth of crystals. Most importantly, the structure can ensure that the heating temperature field gradient is ensured to be more than 30 ℃/cm, and provides more ideal temperature field gradient conditions for crystal growth. In addition, in the crystal preparation process, an independent Cd partial pressure container is additionally arranged on the growth ampoule, and Cd lost due to Cd partial pressure in the cadmium zinc telluride crystal growth process is compensated by regulating and controlling the temperature of the Cd partial pressure container, so that the segregation of the stoichiometric ratio in the crystal growth process is inhibited.

The technical scheme adopted by the invention is as follows:

a preparation device of low-defect tellurium-zinc-cadmium crystals comprises a crystal growth furnace, a power supply control cabinet and a crystal growth ampoule provided with a Cd partial pressure container, wherein the upper end and the lower end of the crystal growth furnace are provided with sealing plugs, and the middle of the crystal growth furnace is provided with a furnace shell; a furnace body heating area formed by stacking heating units with different sizes and heat insulation plates is sequentially arranged in the furnace shell from top to bottom, and each heating unit is provided with an electrode and a cable which are respectively communicated with the power supply control cabinet; a temperature control couple and a temperature measurement couple are arranged in different areas, the couples are connected with a temperature controller on a power supply control cabinet through signal wires, and related crystal growth control parameters are arranged in the temperature controller; the crystal growth furnace also comprises a support frame of the crystal growth ampoule and a crystal growth ceramic furnace tube; a crystal growth pBN crucible is also arranged in the crystal growth ampoule.

Furthermore, a Cd partial pressure container is additionally arranged on the crystal growth ampoule, and the temperature of the Cd partial pressure container is controlled to compensate the stoichiometric segregation caused by Cd partial pressure in the crystal growth process in real time;

further, the temperature controller is provided with a temperature alarm, and when a furnace wire or a couple of the heating unit breaks, the alarm sends out an alarm signal.

Further, the crystal growth furnace is a non-equal-diameter cylindrical crystal growth furnace, and the furnace shell is in a non-equal-diameter cylindrical shape with a large upper part and a small lower part.

Further, the crystal growth furnace comprises not less than 10 sections of independent heating units.

Further, the heating units are separated by a heat insulation plate.

Preferably, the size of the heating unit is reduced from top to bottom, the size of the upper end is 200mm, and the diameter of the lower end is 140 mm.

A preparation method of a low-defect cadmium zinc telluride crystal comprises the following steps:

A. ingredients

In a hundred-grade ultra-clean room, high-purity raw materials (the purity is more than or equal to 7N) such as Te, Cd and Zn are weighed according to the stoichiometric ratio, the raw materials are mixed and then are loaded into a synthetic quartz crucible coated with a carbon film, and after vacuumizing, a quartz tube is sealed and sintered.

B. Synthesis of

The synthesis of the cadmium zinc telluride material is a key technology in a long preparation process, and tube cracking and even explosion can easily occur if the control is not proper. Putting the vacuum sealed quartz crucible into a special synthetic furnace, slowly heating up by 10 ℃/h, and gradually melting Cd into liquid when the temperature is heated to the melting point (320.9 ℃) of the Cd; when the temperature is continuously heated to be near the melting point (449.5 ℃) of Te, Te is melted into liquid, when Te melt meets Cd melt, the Te melt and Cd melt are subjected to violent combination reaction, a large amount of heat is released, the surrounding materials are rapidly heated by the rapidly accumulated heat, the process is easy to crack tubes, and therefore, the constant temperature of 1015 h is kept in the period of time to ensure that the raw materials are fully combined and reacted. And then, continuously heating the synthesis furnace to about 800 ℃, so that the elementary substances which are not fully subjected to the chemical combination reaction and are wrapped by the tellurium-zinc-cadmium are broken through the wrapping, further performing the chemical combination reaction, and cooling the tellurium-zinc-cadmium polycrystal to room temperature after the chemical combination reaction is finished.

C. Pipe replacement

Taking the synthesized tellurium-zinc-cadmium polycrystal out of the quartz crucible in a hundred-grade ultra-clean room, putting the tellurium-zinc-cadmium polycrystal and the seed crystal into a pBN crucible, putting a Cd source with certain mass into a Cd partial pressure container of a quartz ampoule, putting a tellurium-zinc-cadmium material and the pBN crucible together into the quartz ampoule with the Cd partial pressure container, vacuumizing, sealing and sintering.

D. Charging furnace

And (3) putting the sealed and sintered quartz ampoule into a non-isometric crystal growth furnace. In order to meet the requirements of the crystal growth furnace and the actual process, the quartz ampoule is fixed on a crystal growth crucible support in the crystal growth furnace.

E. Crystal growth

And inputting the related crystal growth temperature and time into a temperature field control system according to the requirements of the tellurium-zinc-cadmium crystal growth temperature field. During the period, the accurate control of different temperatures of different parts is required, the movement of a solid-liquid interface of crystal growth is realized through the slow movement of a temperature field, and the tellurium-zinc-cadmium material is required to be incapable of moving in the whole crystal growth process. The temperature gradient is required to be more than or equal to 30 ℃/cm in the period. In addition, the Cd partial pressure of the tellurium-zinc-cadmium crystal can be represented by the formula log₁₀And (3) obtaining the value P-5960.2/K +4.7191 (in the formula, K is the temperature of the formula K, and P is the atm), and controlling the temperature of a Cd source to be 700-900 ℃, preferably 750-850 ℃ by using experience and experimental feedback.

F. Temperature reduction

And after the crystal growth is finished, cooling the tellurium-zinc-cadmium crystal by 5 ℃/h until the room temperature is reached.

G. Slicing

After the crystal growth is finished, cutting the crucible open, and taking out the crystal ingot; grinding the surface of the crystal ingot, and analyzing the distribution conditions of crystal grains and twin crystals; and determining the crystal grain to be sliced and the cutting direction, and carrying out directional slicing by using an inner circle slicing machine according to the crystal direction required by the later process. The working principle of the invention is as follows:

the crystal preparation method adopts the improved vertical Bridgman method, so that the cadmium zinc telluride crystal is kept still in the preparation process, and the movement of a solid-liquid interface in the crystal growth is realized through the movement of a temperature field, thereby avoiding the reduction of the crystal quality caused by the disturbance of the solid-liquid interface in the preparation process of the crystal. The crystal growth device comprises a crystal growth furnace, a power supply control cabinet and a crystal growth ampoule provided with a Cd partial pressure container, wherein the upper end and the lower end of the crystal growth furnace are provided with sealing plugs, the middle of the crystal growth furnace is provided with a furnace body heating area which is formed by stacking heating units with different sizes and a thermal baffle from top to bottom in sequence in the furnace shell, each heating unit is provided with an electrode and a cable which are respectively communicated with the power supply control cabinet, a temperature control couple and a temperature measurement couple are arranged in different areas, the couples are connected with a temperature controller on the power supply control cabinet through signal lines, the temperature controller is provided with a related crystal growth control system, the temperature control system measures the temperature of the actual crystal growth surface through the couples, feeds the actual temperature back to the temperature controller through the signal lines, and then adjusts the power of the heating power supply in the area to realize the accurate control of temperature fields in each area in the crystal preparation process; the crystal growth furnace also comprises a support frame of the crystal growth ampoule and a crystal growth ceramic furnace tube; a crystal growth pBN crucible is arranged in the crystal growth ampoule. In addition, the furnace body is also provided with a temperature alarm, and when a furnace wire or a couple of the heating unit breaks, the alarm sends out an alarm signal and feeds back the alarm signal to crystal growth workers in time. The device is suitable for preparing high-quality and low-defect cadmium zinc telluride crystals, has no less than 10 sections of heating units, can accurately control different temperatures of different parts in the growth process of the cadmium zinc telluride crystals, avoids the influence of disturbance on the solid-liquid interface shape of the cadmium zinc telluride crystal growth due to the movement of mechanical equipment, and forms a vibration-free growth environment; meanwhile, each heating temperature zone is separated from the non-equal-diameter structure of the furnace body by a heat insulation plate, so that the gradient requirement of a temperature field in the preparation process of the cadmium zinc telluride crystal is ensured. In addition, a Cd partial pressure container is additionally arranged in a preparation ampoule of the cadmium zinc telluride crystal, and the Cd lost due to Cd partial pressure in the crystal growth process is compensated in real time by regulating and controlling the temperature of the Cd partial pressure container, so that the segregation of a chemical meter in the crystal growth process is inhibited, and the quality of the cadmium zinc telluride crystal is improved. More importantly, the equipment is compact in whole machine, small in occupied area, provided with a programmed control system and capable of stably and repeatedly preparing the tellurium-zinc-cadmium single crystal.

The invention has the beneficial effects that:

the growth of the tellurium-zinc-cadmium single crystal with the diameter of 90mm is realized by the equipment and the growth method. The area of the cadmium zinc telluride sheet after growth reaches 70mm multiplied by 70 mm; the size of the defect of the sedimentary phase is less than or equal to 1 mu m, and the density is less than or equal to 3000cm^-2(ii) a The density of corrosion pits is less than or equal to 5 multiplied by 10⁵cm^-2(ii) a The full Width at half maximum (FWHM) was 21.21 arcs.

Drawings

FIG. 1 is a schematic view of the structure of a crystal production apparatus of the present invention.

FIG. 2 is a schematic representation of a 70mm by 70mm CdZnTe wafer in an example of the present invention.

FIG. 3 is a schematic diagram of the deposition phases of a cadmium zinc telluride ingot 1 in an example of the present invention.

FIG. 4 is a graphical representation of Etch Pit Density (EPD) for cadmium zinc telluride ingot 1 in an example of the invention.

Detailed Description

The technical scheme is described in detail with reference to the accompanying drawings and the detailed description.

As shown in figure 1, the preparation method and the device for the low-defect tellurium-zinc-cadmium crystal comprise a crystal growth furnace 2, a power supply control cabinet 1 and a crystal growth ampoule 3 provided with a Cd partial pressure container, wherein the upper end and the lower end of the crystal growth furnace 2 are provided with sealing plugs 4, and the middle of the crystal growth furnace is provided with a furnace shell 11; a furnace body heating area formed by stacking heating units 6 with different sizes and a heat insulation plate 8 is sequentially arranged in the furnace shell 11 from top to bottom, and each heating unit 6 is provided with an electrode and a cable 10 which are respectively communicated with the power supply control cabinet 1; temperature control couples and temperature measurement couples 7 are arranged in different areas, the couples 7 are connected with a temperature controller 12 on the power control cabinet 1 through a signal wire 13, and related crystal growth control parameters are arranged in the temperature controller 12; the crystal growth furnace 2 also comprises a support frame 9 of a crystal growth ampoule 3 and a crystal growth ceramic furnace tube 14; a crystal growth pBN crucible 5 is also arranged in the crystal growth ampoule 3.

The crystal growth ampoule 3 is additionally provided with a Cd partial pressure container, and the temperature of the Cd partial pressure container is controlled to compensate the stoichiometric segregation caused by Cd partial pressure in the crystal growth process in real time; the temperature controller 12 is provided with a temperature alarm which sends out an alarm signal when a furnace wire or a galvanic couple 7 of the heating unit 6 is broken.

The crystal growth furnace 2 is a non-equal-diameter cylindrical crystal growth furnace, and the furnace shell 11 is in a non-equal-diameter cylindrical shape with a large upper part and a small lower part.

The crystal growth furnace 2 contains not less than 10 sections of independent heating units 6.

The heating units 6 are separated by heat insulation plates 8. The size of the heating unit 6 from the top down is reduced, the size of the upper end is 200mm, and the diameter of the lower end is 140 mm.

Example (b):

the example provides a preparation method of a low-defect cadmium zinc telluride crystal, and a cadmium zinc telluride crystal preparation device provided by the invention is used.

A. Ingredients

In a hundred-grade ultra-clean room, high-purity raw materials (N is more than or equal to 7N) such as Te, Cd and Zn are weighed according to the stoichiometric ratio, the raw materials are mixed and then loaded into a synthetic quartz crucible coated with a carbon film, and after vacuumizing, a quartz tube is sealed and sintered.

B. Synthesis of

The synthesis of the cadmium zinc telluride material is a key technology in a long preparation process, and tube cracking and even explosion can easily occur if the control is not proper. Putting the vacuum sealed quartz crucible into a special synthetic furnace, slowly heating up by 10 ℃/h, and gradually melting Cd into liquid when the temperature is heated to the melting point (320.9 ℃) of the Cd; when the temperature is continuously heated to be near the melting point (449.5 ℃) of Te, Te starts to melt into liquid, when Te melt meets Cd melt, the Te melt and Cd melt generate violent combination reaction, a large amount of heat is released, the surrounding materials are rapidly heated by the rapidly accumulated heat, and the process is easy to crack tubes, so that the constant temperature time of 10-15 hours is kept in the period of time to ensure that the raw materials are fully combined and reacted. And then, continuously heating the synthesis furnace to about 800 ℃, so that the elementary substances which are not fully subjected to the chemical combination reaction and are wrapped by the tellurium-zinc-cadmium are broken through the wrapping, further performing the chemical combination reaction, and cooling the tellurium-zinc-cadmium polycrystal to room temperature after the chemical combination reaction is finished.

C. Pipe replacement

Taking the synthesized tellurium-zinc-cadmium polycrystal out of the quartz crucible in a hundred-grade ultra-clean room, putting the tellurium-zinc-cadmium polycrystal and the seed crystal into a pBN crucible, putting a Cd source with certain mass into a Cd partial pressure container of a quartz ampoule, putting a tellurium-zinc-cadmium material and the pBN crucible together into the quartz ampoule with the Cd partial pressure container, vacuumizing, sealing and sintering.

D. Charging furnace

The sealed and sintered quartz ampoule was charged into a non-isometric crystal growth furnace as shown in FIG. 1. In order to meet the requirements of the crystal growth furnace and the actual process, the quartz ampoule is fixed on a crystal growth crucible support in the crystal growth furnace.

E. Crystal growth

Inputting related crystal growth into a temperature field control system according to the requirements of the tellurium-zinc-cadmium crystal growth temperature fieldTemperature and time. During the period, the accurate control of different temperatures of different parts is required, the movement of a solid-liquid interface of crystal growth is realized through the slow movement of a temperature field, and the tellurium-zinc-cadmium material is required to be incapable of moving in the whole crystal growth process. The temperature gradient is required to be more than or equal to 30 ℃/cm in the period. In addition, the Cd partial pressure of the tellurium-zinc-cadmium crystal can be represented by the formula log₁₀And (3) calculating P-5960.2/K +4.7191(P: atm), and controlling the temperature of the Cd source to be 700-900 ℃, preferably 750-850 ℃ by using experience and experimental feedback.

F. Temperature reduction

And after the crystal growth is finished, cooling the tellurium-zinc-cadmium crystal by 5 ℃/h until the room temperature is reached.

G. Slicing

After the crystal growth is finished, cutting the crucible open, and taking out the crystal ingot; grinding the surface of the crystal ingot, and analyzing the distribution conditions of crystal grains and twin crystals; and determining the crystal grain to be sliced and the cutting direction, and carrying out directional slicing by using an inner circle slicing machine according to the crystal direction required by the later process.

The low-defect cadmium zinc telluride single crystal is prepared by the method, and the area of the cadmium zinc telluride sheet reaches 70mm multiplied by 70 mm; the size of the defect of the sedimentary phase is less than or equal to 1 mu m, and the density is less than or equal to 3000cm^-2(ii) a The density of corrosion pits is less than or equal to 5 multiplied by 10⁵cm^-2。