CN104357902A - Synthesizing device and method for synthesizing Cd(1-x)ZnxTe polycrystal by utilizing temperature gradient - Google Patents

Abstract

The invention discloses a synthesis device and method for synthesizing cadmium zinc telluride polycrystal by using temperature gradient. The synthesis device includes a heating alumina furnace, a lining furnace, a temperature control system, and a reaction vessel, and can carry out two stages of independent or combined temperature rise and fall. The method realizes the control of the temperature gradient by changing the temperature field distribution in the high-temperature zone and the low-temperature zone, realizes the control of the synthesis reaction rate by changing the distribution mode of the crystal material; and reduces the loss of the crystal material after synthesis by changing the temperature of the high-temperature zone and the low-temperature zone The resulting stoichiometric shift. The beneficial effects of the present invention are as follows: (1) The temperature gradient method combined with the distribution of crystal material makes the reaction process uniform and controllable, eliminating the risk of cracking tubes caused by violent reactions. (2) The synthesized ingot has almost no crystal material loss when the tube is replaced twice to grow CdZnTe single crystal, which ensures that the chemical equilibrium metering ratio does not deviate. (3) It can directly synthesize CdZnTe polycrystalline ingots with specifications of 2 inches, 3 inches and 4 inches.

Description

A synthetic device and method for synthesizing polycrystalline cadmium zinc telluride using temperature gradient

technical field

The invention specifically relates to a reaction device and method for synthesizing cadmium zinc telluride polycrystals using a temperature gradient, with the purpose of realizing the synthesis of large-scale cadmium zinc telluride polycrystals with low risk and no stoichiometric ratio deviation, and belongs to the technical field of semiconductor materials and devices.

Background technique

Cadmium zinc telluride (Cd _1-x Zn _x Te) crystal material is an ideal infrared focal plane detector substrate material and superior infrared window material. Not only that, Cd _1-x Zn _x Te crystals also have broad application prospects in the preparation of x and gamma ray detectors, solar cells, and optical modulators. At present, large-scale infrared focal plane devices require larger-sized CdZnTe single crystal substrates, and in the CdZnTe single crystal preparation process, the successful synthesis of large-diameter polycrystalline materials is to obtain large-sized CdZnTe single crystal substrates key premise.

The large-scale industrial synthesis of CdZnTe at the present stage often encounters the explosion of quartz crucible containers caused by violent chemical reactions, which leads to material oxidation and scrapping and equipment damage, resulting in great economic losses. In general, CdZnTe is directly synthesized from various elements under liquid phase conditions. However, due to the violent reaction between Te and Cd during the synthesis process, a large amount of heat will be released, which will cause the pressure of cadmium in the quartz tube to increase, and eventually exceed the withstand pressure range of the quartz tube, resulting in cracked tube leakage. At the same time, with the increase of the diameter of the quartz tube, the pressure resistance of the quartz crucible decreases, and more heat is released by the reaction after the crystal material increases, which is more likely to cause a synthetic cracking accident. At the same time, the deposition of the crystal material on the wall of the quartz tube causes the CdZnTe polycrystalline material to deviate from the stoichiometric ratio, and also causes dislocations, precipitation and other defects in the later crystal growth.

Most of the current CdZnTe synthesis technologies are mainly based on the synthesis technology of CdZnTe, which not only has a low yield per tube, but also does not fundamentally solve the problems of cracked tubes and crystal material loss during synthesis. Invention patent CN102086031 A proposes a liquid-phase synthesis method of cadmium telluride. In this patent, the polycrystalline material single tube synthesized each time is at most 700g, which is difficult to meet the demand for growing large-diameter cadmium telluride. Invention patent CN 103420346 A proposes a method for preparing cadmium telluride. In this patent, cadmium telluride is synthesized twice, and each batch of synthesis must be separately loaded into two graphite boats and two quartz tubes, and in the synthesis In the process, inert gas and reducing gas need to be introduced, and the process is cumbersome and the cycle is long. In addition, it is necessary to carry out fine crushing and screening after the primary synthesis, which makes it easier to introduce secondary pollution and crystal material loss. Invention patent CN 103409800 A proposes a large-diameter cadmium telluride or cadmium zinc telluride polycrystalline bar material synthesis device and preparation method. This method uses a graphite crucible with a built-in plug in a quartz tube for synthesis, but this method cannot fundamentally The reaction rate in the synthesis process of CdZnTe or CdTe is controlled, and at the same time, there are still problems of excessive reaction and loss of crystal material after synthesis in the synthesis process.

Contents of the invention

Based on the relevant problems existing in the current synthesis technology of cadmium telluride or cadmium zinc telluride, the present invention proposes a device and method for synthesizing polycrystalline cadmium zinc telluride using a temperature gradient.

One of the objectives of the present invention is to provide a synthetic device for industrial large-scale synthesis of CdZnTe.

Another object of the present invention is to provide a method for synthesizing CdZnTe polycrystal by using the above-mentioned equipment, which can make the reaction process uniform and controllable, and reduce the risk of tube cracking caused by violent reaction. At the same time, it is ensured that the synthesized ingot has almost no loss of crystal material when the tube is changed twice to grow CdZnTe single crystal, so as to ensure that the chemical equilibrium metering ratio does not deviate.

For this reason, the present invention provides following technical scheme:

A reaction device for synthesizing cadmium zinc telluride polycrystal by using temperature gradient, which is composed of an alumina furnace 7, a quartz lining tube 10, a rear temperature control thermocouple 6, a rear temperature control thermocouple 9, and a quartz crucible 8. It is characterized in that the outer surface of the entire furnace body is a furnace body shell 4 made of stainless steel, and the furnace body insulation cotton 2 is used to insulate and keep heat between the shell 4 and the alumina furnace 7, and the entire furnace body insulation cotton 2 is divided into two parts by the middle heat insulation block 3 Part of the independent temperature control zone, the ratio of the length of the high temperature section to the low temperature section is: 1:1~1:2, and the temperature of the furnace body is controlled by the front temperature control thermocouple 9 and the rear temperature control thermocouple 6 respectively. Quartz lining pipe 10 is in the alumina furnace 7, and quartz crucible 8 is placed in the quartz lining pipe 10 before and after the hearth and blocked with furnace mouth insulation block 1 and furnace bottom insulation block 5 respectively.

The reaction device for synthesizing cadmium zinc telluride polycrystal by using temperature gradient is characterized in that a quartz lined tube 10 is used.

The reaction device for synthesizing cadmium zinc telluride polycrystal by using temperature gradient is characterized in that the insulation cotton 2 is aluminum silicate ceramic fiber loose cotton.

The reaction device for synthesizing cadmium zinc telluride polycrystal by using temperature gradient is characterized in that the middle heat insulating block 3 is mullite lightweight heat insulating brick.

The reaction device for synthesizing cadmium zinc telluride polycrystal by using temperature gradient is characterized in that the furnace mouth insulation block 1 and the furnace bottom insulation block 5 are made of silicon-aluminum Sierra fiber blanket.

The method for synthesizing cadmium zinc telluride polycrystals using a temperature gradient in the reaction device is characterized in that the method includes the following steps:

(1) At a suitable temperature, a uniform and firm carbon film is coated on the inside of a clean quartz tube by acetone cracking.

(2) In a class 100 clean room, take tellurium, zinc, and cadmium, and weigh 7N Te, Zn, and Cd according to the requirements of the Zn component in Cd _1-x Zn _x Te, and put them in sequence according to a certain arrangement method. Put it into the quartz tube, and ensure that there are Te blocks at the mouth of the tube and at the bottom of the tube. The layout method is as follows:

①The length of carbon coating on the quartz tube is L, the average diameter of Te blocks is D ₁ , the average length of Cd rods is D ₂ , and Zn is generally relatively small in components (arranged in the Cd layer).

②L=N(D ₁ +D ₂ )+D ₁ , N≈3~8, N is the number of layers of (Te+Cd) arrangement.

(3) Put the loaded quartz tube into the degassing furnace, turn on the vacuum pump to draw a vacuum, when the vacuum degree

When it reaches 1×10 ^-5 Pa～5×10 ^-5 Pa, start to heat up the degassing furnace, and the temperature range of the degassing furnace is 200～300℃. When the vacuum degree reaches 1×10 ^-6 Pa～5×10 ^-6 Pa, seal the quartz tube. Then stop vacuuming and degassing furnace cooling in turn (cooling rate is 5° C./h).

(4) Put the quartz tube into the synthesis furnace and start the heating and cooling process:

①The high temperature zone rises to 460～520℃ at the speed of 1～8℃/min, the low temperature zone rises to 320℃～400℃ at the speed of 1～6℃/min, and keeps the temperature for 1～3 hours, so that the high temperature zone and the low temperature zone The temperature difference between 60 ~ 200 ℃.

②Raise the temperature of the high and low temperature zone at a rate of 1-6°C/min. The temperature ranges of the high-temperature zone and the low-temperature zone are 1100-1140°C and 1100-1140°C respectively, and the homogenization constant temperature time is 10-20 hours.

③ Reduce the temperature of the high temperature zone and the low temperature zone together to the range of 1000℃～1100℃ at the speed of 1～3℃/min.

④ Reduce the temperature of the high temperature zone and the low temperature zone together to within the range of 10℃～100℃ at the speed of 1～6℃/min.

(5) Open the furnace, take out the quartz tube, open the quartz tube, and take out the CdZnTe polycrystalline product in the ultra-clean room.

The present invention has the following advantages:

(1) The temperature gradient method combined with the crystal material distribution makes the reaction process uniform and controllable, reducing the risk of cracking tubes caused by violent reactions. (2) The synthesized ingot has almost no crystal material loss when the tube is replaced twice to grow CdZnTe single crystal, which ensures that the chemical equilibrium metering ratio does not deviate. (3) It can directly synthesize CdZnTe polycrystalline ingots with specifications of 2 inches, 3 inches and 4 inches, and is widely applicable to high-quality continuous synthesis of CdZnTe polycrystalline ingots of various specifications.

Description of drawings

Fig. 1 is the structural representation of device of the present invention: (1) furnace mouth insulation block; (2) body of furnace insulation cotton; (3) middle insulation block; (4) stainless steel body of furnace shell; (5) furnace bottom insulation block; (6) rear temperature control thermocouple; (7) alumina furnace; (8) quartz crucible; (9) front temperature control thermocouple; (10) quartz lining tube.

Fig. 2 is a process flow chart of the temperature gradient method of the present invention.

Fig. 3 is the crystal deposition situation of the synthesis example of Cd _0.96 Zn _0.04 Te synthesized by the method described in this patent: Fig. a. Conventional method, Fig. b. Specific example 1, Fig. c. Specific example 2, Fig. d. Specific implementation Example 3.

Detailed ways

The present invention will be further elaborated below by specific example, but the preferred embodiment provided by the present invention is only used to illustrate the present invention, without any limitation to the scope of the present invention, and any modification and modification that can be easily realized by those skilled in the art Variations are within the scope of the invention and the appended claims.

As shown in Figure 1, the synthetic device of the present invention comprises: a kind of reaction device utilizing temperature gradient method to synthesize cadmium zinc telluride (Cd1-xZnxTe) polycrystal, it is characterized in that, described device comprises alumina furnace, lining furnace, Temperature control system, reaction vessel. The outside of the entire furnace body is a furnace body shell 4 made of stainless steel, and the furnace body insulation cotton 2 is used to insulate and keep heat between the shell 4 and the alumina furnace 7, and the entire furnace body insulation cotton 2 is divided into two independent parts by the middle heat insulation block 3 In the temperature control area, the ratio of the length of the high temperature section to the low temperature section is: 1:1 to 1:2, and the temperature of the furnace body is controlled by the front temperature control thermocouple 9 and the rear temperature control thermocouple 6 respectively. Quartz protection lining pipe 10 is in the alumina furnace 7, and quartz crucible 8 is placed in the quartz protection lining pipe 10 before and after the hearth and blocked with furnace mouth insulation block 1 and furnace bottom insulation block 5 respectively.

Combined with the synthesis device provided by the patented method, the method of synthesizing CdZnTe polycrystal with temperature gradient is described in detail by taking the synthesis of Cd _0.96 Zn _0.04 Te polycrystalline rod with a diameter of 60 mm as an example. According to the described steps, enumerate the following specific examples for reference.

Specific embodiment 1

1) A uniform and firm carbon film is coated on the inside of a clean quartz tube by cracking with acetone.

2) In the 100-class clean room, according to the diameter and length of the ingot to be synthesized, according to the requirements of the Zn component in Cd _0.96 Zn _0.04 Te, calculate the required high-purity raw materials for tellurium, zinc, and cadmium, and then use an electronic balance Weigh separately. Then put 7N Te, Zn, and Cd into the quartz tube in sequence according to a certain arrangement method, so as to ensure that the mouth of the tube and the bottom of the tube are all Te blocks. According to the arrangement method, N≈6, that is, the ingredients are divided into 6 layers.

3) Put the prepared quartz tube into the degassing furnace, turn on the vacuum pump to evacuate, and start heating the degassing furnace when the vacuum degree reaches 1×10 ^-5 Pa, and the temperature of the degassing furnace is 200°C. When the vacuum degree reaches 1×10 ^-6 Pa, seal the quartz tube. Then stop vacuuming and degassing furnace cooling in turn (cooling rate is 5° C./h).

4) Put the quartz tube into the synthesis furnace and start the heating and cooling process:

① The high temperature zone rises to 460-520°C at a rate of 1.5°C/min, the low-temperature zone rises to 320°C-400°C at a rate of 1°C/mm, and the temperature is kept constant for 1 hour, so that the temperature difference between the high-temperature zone and the low-temperature zone is 60 ~200℃.

②Then raise the temperature of the high and low temperature zone at a rate of 1°C/min. The temperature of the high temperature zone and the low temperature zone are 1100-1120°C respectively, within the range of 1100-1120°C, and the homogenization constant temperature time is 10 hours.

③ Lower the temperature in the high temperature zone and the low temperature zone together at a rate of 1°C/min to a range of 1000°C to 1100°C.

④ Lower the temperature in the high temperature zone and the low temperature zone together at a rate of 1.5°C/min to the range of 20°C to 50°C.

5) Open the furnace, take out the quartz tube, open the quartz tube, take out the cadmium zinc telluride polycrystalline product in the ultra-clean room, and obtain a Cd _0.96 Zn _0.04 Te polycrystalline rod material with a diameter of 60 mm.

Specific embodiment 2

1) A uniform and firm carbon film is coated on the inside of a clean quartz tube by cracking with acetone.

2) In the 100-class clean room, according to the diameter and length of the ingot to be synthesized, according to the requirements of the Zn component in Cd _0.96 Zn _0.04 Te, calculate the required high-purity raw materials for tellurium, zinc, and cadmium, and then use an electronic balance Weigh separately. Then put 7N Te, Zn, and Cd into the quartz tube in sequence according to a certain arrangement method, so as to ensure that the mouth of the tube and the bottom of the tube are all Te blocks. According to the arrangement method, N≈5, that is, the ingredients are divided into 5 layers.

3) Put the prepared quartz tube into the degassing furnace, turn on the vacuum pump to evacuate, and start heating the degassing furnace when the vacuum degree reaches 3×10 ^-5 Pa, and the temperature range of the degassing furnace is 250°C. When the vacuum degree reaches 3×10 ^-6 Pa, seal the quartz tube. Then stop vacuuming and degassing furnace cooling in turn (cooling rate is 5° C./h).

4) Put the quartz tube into the synthesis furnace and start the heating and cooling process:

① The high temperature zone rises to 460-520°C at a rate of 2°C/min, the low-temperature zone rises to 320°C-400°C at a rate of 1.5°C/mm, and keeps the temperature for 2 hours, so that the temperature difference between the high-temperature zone and the low-temperature zone is 60 ~200℃.

②Then heat up the high and low temperature zone at a rate of 2°C/min. The temperature in the high temperature zone and the low temperature zone are 1120-1130°C and 1120-1140°C respectively, and the homogenization constant temperature time is 15 hours.

③ Reduce the temperature of the high temperature zone and the low temperature zone together to the range of 1000℃～1100℃ at the speed of 1.5℃/min.

④ Lower the temperature in the high temperature zone and the low temperature zone together at a rate of 2°C/min to the range of 50°C to 80°C.

5) Open the furnace, take out the quartz tube, open the quartz tube, take out the cadmium zinc telluride polycrystalline product in the ultra-clean room, and obtain a Cd _0.96 Zn _0.04 Te polycrystalline rod material with a diameter of 60 mm.

Specific embodiment 3

1) A uniform and firm carbon film is coated on the inside of a clean quartz tube by cracking with acetone.

2) In the 100-class clean room, according to the diameter and length of the ingot to be synthesized, according to the requirements of the Zn component in Cd _0.96 Zn _0.04 Te, calculate the required high-purity raw materials for tellurium, zinc, and cadmium, and then use an electronic balance Weigh separately. Then put 7N Te, Zn, and Cd into the quartz tube in sequence according to a certain arrangement method, so as to ensure that the mouth of the tube and the bottom of the tube are all Te blocks. According to the arrangement method, N≈4 is obtained, that is, the ingredients are divided into 4 layers.

3) Put the prepared quartz tube into the degassing furnace, turn on the vacuum pump to evacuate, and start heating the degassing furnace when the vacuum degree reaches 5×10 ^-5 Pa, and the temperature range of the degassing furnace is 300°C. When the vacuum degree reaches 5×10 ^-6 Pa, seal the quartz tube. Then stop vacuuming and degassing furnace cooling in turn (cooling rate is 5° C./h).

4) Put the quartz tube into the synthesis furnace and start the heating and cooling process:

① The high temperature zone rises to 460-520°C at a rate of 3°C/min, the low-temperature zone rises to 320°C-400°C at a rate of 2°C/mm, and the temperature is kept constant for 2 hours, so that the temperature difference between the high-temperature zone and the low-temperature zone is 60- between 200°C.

②Then raise the temperature of the high and low temperature zone at a rate of 3°C/min. The temperature of the high temperature zone and the low temperature zone are 1130-1140°C respectively, within the range of 1130-1140°C, and the homogenization constant temperature time is 20 hours.

③ Reduce the temperature of the high temperature zone and the low temperature zone together to the range of 1000℃～1100℃ at the speed of 2℃/min.

④ Reduce the temperature of the high temperature zone and the low temperature zone together to a range of 80°C to 100°C at a rate of 3°C/min.

5) Open the furnace, take out the quartz tube, open the quartz tube, take out the cadmium zinc telluride polycrystalline product in the ultra-clean room, and obtain a Cd _0.96 Zn _0.04 Te polycrystalline rod material with a diameter of 60 mm.

The embodiments in the present invention are only used to illustrate the present invention, and do not constitute a limitation to the scope of the claims. Other substantially equivalent substitutions that can be imagined by those skilled in the art are within the protection scope of the present invention.

Claims (6)

1. utilize thermograde to synthesize a synthesizer for tellurium zinc cadmium polycrystalline, it comprises aluminum oxide burner hearth (7), quartz lining pipe (10), rear temperature-controlling thermal couple (6), rear temperature-controlling thermal couple (9), quartz crucible (8), is characterized in that:

It is the body of heater shell (4) made by stainless steel outside whole body of heater, with the isolated insulation of furnace insulation cotton (2) between shell (4) and aluminum oxide burner hearth (7), whole furnace insulation cotton (2) is divided into two portions independently temperature control district by middle heat insulation (3), the length ratio of high temperature section and low-temperature zone is: 1:1 ~ 1:2, and it is controlled the temperature of body of heater respectively by front temperature-controlling thermal couple (9) and rear temperature-controlling thermal couple (6).Quartz lining pipe (10) in (7), is placed in quartz lining pipe (10) before and after quartz crucible (8) burner hearth and is used fire door insulation block (1) and furnace bottom insulation block (5) to block respectively in aluminum oxide burner hearth.

2. utilize thermograde to synthesize the synthesizer of tellurium zinc cadmium polycrystalline as claimed in claim 1, it is characterized in that: described insulating cotton (2) is aluminosilicate property ceramic fiber loose wool.

3. utilize thermograde to synthesize the synthesizer of tellurium zinc cadmium polycrystalline as claimed in claim 1, it is characterized in that by middle heat insulation (3) be mullite light heat-insulation brick.

4. utilize thermograde to synthesize the synthesizer of tellurium zinc cadmium polycrystalline as claimed in claim 1, its feature exists: described fire door insulation block (1), and the material of furnace bottom insulation block (5) is sal Celafibre blanket.

5., based on the tellurium zinc cadmium polycrystal synthesis method utilizing thermograde to synthesize the synthesizer of tellurium zinc cadmium polycrystalline described in claim 1, it is characterized in that, described method comprises the steps:

1) the even firmly carbon film of last layer is coated with in the silica tube inside of cleaning by acetone cracking;

2) tellurium is got, zinc, cadmium, according to Cd _1-xzn _xthe requirement of Zn component in Te, weigh the Te of 7N, Zn, Cd put into silica tube successively according to certain arrangement method, and mouth of pipe place and pipe bottom are all Te blocks;

3) charged silica tube is put into except steam stove, open vacuum pump evacuation, when vacuum tightness reaches 1 × 10 ^-5pa ~ 5 × 10 ^-5start during Pa to heat up except steam stove, degasification furnace temperature scope is at 200 ~ 300 DEG C.When vacuum tightness reaches 1 × 10 ^-6pa ~ 5 × 10 ^-6during Pa, by silica tube involution.Stop successively vacuumizing and remove steam stove cooling, rate of temperature fall is 5 DEG C/h again;

4) silica tube is put into synthetic furnace, starts to heat up and temperature reduction technology:

1. high-temperature zone is raised to 460 ~ 520 DEG C with the speed of 1 ~ 8 DEG C/min, and cold zone is raised to 320 DEG C ~ 400 DEG C with the speed of 1 ~ 6 DEG C/min, and constant temperature 1 ~ 3 hour makes the temperature gap of high-temperature zone and cold zone between 60 ~ 200 DEG C;

2. incite somebody to action height temperature-raising region temperature raising with the speed of 1 ~ 6 DEG C/min, the temperature range of height warm area is respectively 1100 ~ 1140 DEG C, 1100 ~ 1140 DEG C, and homogenizing constant temperature time is 10 ~ 20 hours;

3. with the speed of 1 ~ 2 DEG C/min, the temperature of height warm area is down in the scope of 1000 DEG C ~ 1100 DEG C respectively;

4. with the speed of 1 ~ 4 DEG C/min, the temperature of height warm area is down in the scope of 10 DEG C ~ 100 DEG C respectively;

5) open burner hearth, take out silica tube, open silica tube, in clean room, take out tellurium zinc cadmium product.

6. a kind of tellurium zinc cadmium polycrystal synthesis method based on utilizing thermograde to synthesize the synthesizer of tellurium zinc cadmium polycrystalline described in claim 1 as claimed in claim 6, is characterized in that: in step 2) described in Te, the arrangement method of Zn, Cd is as follows:

1. silica tube utter misery length is L, Te block mean diameter is D ₁, Cd rod mean length is D ₂, Zn comes in Cd layer;

2. L=N (D ₁+ D ₂)+D ₁, N ≈ 3 ~ 8, N is the arrangement number of plies of Te+Cd.