A method for reducing the influence of gravity to grow low optical absorption and high uniformity indium lead telluride single crystals

Abstract

A method for growing lead indium telluride single crystals with reduced gravity influence, low optical absorption and high uniformity, which relates to the method for growing lead indium telluride single crystals. It aims to solve the problems of serious crystal cracking, strong optical absorption and uneven distribution of elements inside the crystal existing in the existing PIT crystal growth method. The method: Place the Pb source, In source, Te source and additional In2Te3 in a cylindrical crucible, then add elemental Te into the quartz tube and seal it after melting; Place the quartz tube in an inclined single-temperature zone tube furnace for reaction to obtain PIT polycrystals, and then load the polycrystalline material into a pyrolytic boron nitride crucible with a seed crystal trap and place it in the quartz tube for vacuum sealing; Carry out single crystal growth in a multi-temperature zone horizontal crystal growth furnace to obtain PIT single crystals. The cut 6-mm-thick double-sided polished wafer has a transmittance close to 60% in the 2-3 μm band and an optical absorption less than 0.11 cm ‑1 , and can be used in the industrial, medical and energy fields.

Description

Technical Field

[0001] The invention relates to a method for growing an indium lead telluride single crystal. Background Art

[0002] All-solid-state lasers have become an important direction of laser technology development due to their advantages of small size, high beam quality and high power, and have broad application prospects in important fields such as industry, medicine and energy. All-solid-state lasers mainly rely on frequency conversion technology based on nonlinear optical crystals to obtain the required laser output band. The intrinsic defects of chalcopyrite crystals (such as AgGaS2, AgGaSe2 and ZnGeP2, etc.) for commercial applications in the infrared band, such as low laser damage threshold and two-photon absorption, limit their application in far-infrared high-power solid-state lasers.

[0003] The development of modern infrared laser technology requires new crystals with the following properties: First, they can efficiently utilize the 1064nm laser pump output by Nd:YAG lasers. Second, the new crystals need to cover an output range of more than 10μm. Compared with phosphorus compounds, telluride crystals in chalcogenides have lower phonon energy, which is conducive to obtaining nonlinear optical crystal materials with a transmission range covering the 10-14μm atmospheric window. Ternary telluride PbIn6Te 10 (PIT) crystal is a new type of nonlinear optical material. It belongs to the trigonal system and crystallizes in the R32 space group. It has a light transmission band (1.3-31 μm), suitable birefringence (~0.05), and a large nonlinear coefficient (d 11 =51pm / V). In addition, a 2μm laser can be used to output a 5-25μm continuously tunable laser through optical parametric oscillation technology. Theoretical simulations have proven that the PIT crystal has the ability to achieve 10-30μm laser output.

[0004] PbIn6Te 10 As a type of non-uniform melting compound, the melt composition of PIT crystals is difficult to control during crystal growth. The existing PIT crystal growth methods have serious crystal cracking, strong optical absorption, and uneven distribution of elements inside the crystal, which seriously affect the optical properties of PIT crystals. Therefore, a method for growing high-quality PIT crystals with uniform optical properties is urgently needed. Summary of the invention

[0005] The present invention aims to solve the technical problems of severe crystal cracking, strong optical absorption and uneven distribution of elements inside the crystal in the existing PIT crystal growth method, and provide a method for reducing the influence of gravity on the growth of low optical absorption and high uniformity indium lead telluride single crystal. The method is a single crystal growth method in which the crystal interface is perpendicular to the gravity direction, so as to reduce the large deviation of optical performance caused by the component gap at different positions during the growth of non-uniform molten compound PIT crystal, so that it can meet the requirements of 2.09μm laser pump light parametric oscillation output of mid-to-far infrared laser.

[0006] The method of reducing the influence of gravity to grow low optical absorption and high uniformity indium lead telluride single crystals of the present invention is carried out according to the following steps:

[0007] 1. In an inert atmosphere glove box, weigh Pb source, In source and Te source according to the stoichiometric ratio of Pb:In:Te of 1:6:10, and weigh additional In2Te3 according to 1% to 10% of the total mass of Pb source, In source and Te source;

[0008] 2. Place the Pb source, In source, Te source and additional In2Te3 in a cylindrical crucible, then place the cylindrical crucible in a quartz tube, add 0.01-10.00g of elemental Te into the quartz tube, use a molecular pump to evacuate the quartz tube to a vacuum state, and then use a hydrogen-oxygen flame to melt and seal the quartz tube;

[0009] 3. Heating for solid phase reaction: The sealed quartz tube is placed in an inclined single temperature zone tube furnace with an inclination angle of 0.1° to 30°, and then heated to 750 to 850°C at a rate of 5 to 50°C / h and maintained for 100 hours, and then the temperature is oscillated within the range of 600 to 900°C. After 1 to 10 temperature oscillations, the temperature is cooled to room temperature at a rate of 10 to 50°C / h to obtain PIT polycrystals;

[0010] 4. Load the PIT polycrystalline material prepared in step 3 into a pyrolytic boron nitride crucible with a seed well, and then place the pyrolytic boron nitride crucible into a quartz tube for vacuum sealing; place the quartz tube into a multi-temperature zone horizontal crystal growth furnace and fix it, and the seed well of the pyrolytic boron nitride crucible is located in the low temperature zone; heat the multi-temperature zone horizontal crystal growth furnace, so that the temperature of the high temperature zone in the furnace is rapidly increased to 700-710°C at a rate of 5-50°C / h, and the temperature of the low temperature zone is rapidly increased to 660-670°C at a rate of 5-50°C / h, the temperature field in the gradient zone is 0.1-3°C / cm, and the temperature is kept for 50-100h to fully homogenize the polycrystalline raw material; then cool down at a rate of 0.01-0.1°C / h, and after cooling down to the high temperature zone below 650°C, cool down to room temperature at a rate of 20-50°C / h to obtain a PIT single crystal.

[0011] Furthermore, the Pb source described in step 1 is bulk metallic lead, powdered metallic lead, beaded metallic lead or lead telluride compound.

[0012] Furthermore, the In source in step 1 is bulk metal element indium, powdered metal element indium, beaded metal element indium or indium tritelluride compound.

[0013] Furthermore, the Te source in step 1 is bulk single crystal tellurium, powdered metal tellurium or beaded metal tellurium.

[0014] Furthermore, the crucible in step 2 is made of carbon-coated quartz, high-purity corundum, high-purity graphite or high-purity pyrolytic boron nitride.

[0015] Furthermore, the vacuum state described in step 2 is to vacuum to 10 -4 Below Pa.

[0016] Furthermore, the specific operation of temperature oscillation within the range of 600-900°C in step three is to first reduce the temperature to 600°C at a cooling rate of 10-20°C / h, and then increase the temperature to 900°C at a heating rate of 10-20°C / h and maintain for 20 hours to complete one oscillation.

[0017] Furthermore, the temperature field of the gradient zone in step 4 is 1-2°C / cm.

[0018] Furthermore, the heat preservation time for fully homogenizing the polycrystalline raw material in step 4 is 80 to 100 hours.

[0019] The present invention utilizes Pb source, In source and Te source and additional In2Te3 to perform multiple temperature oscillations in the range of 600-900°C after high-temperature solid-phase reaction, thereby improving the composition uniformity of PIT polycrystals. Then, the polycrystal is used as raw material, and the PIT single crystal is grown by horizontal gradient condensation method in a spontaneous nucleation manner. The additionally added In2Te3 compound is evenly dispersed to various parts of the polycrystalline ingot to maintain the phase stability of the equal-diameter parts of the PIT crystal, and a highly homogenized PIT single crystal is obtained. The PIT crystal has good quality and no cracks, and the optical transmittance of the area with better crystallinity is high. The transmittance of a 6mm thick double-sided polished wafer is close to 60% in the 2-3μm band, and there is no obvious difference in the optical transmittance of different parts. At the same time, the optical absorption of the wafer at 2.09μm is less than 0.11cm -1 , which is conducive to the use of 2.09μm lasers to pump the output of mid- and far-infrared lasers, which can be used in industry, medicine, and energy fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1Schematic diagram of the dual-temperature zone synthesis in step 4 of Example 1; 1 is a crucible, 1-1 is a seed crystal well, 2 is a quartz tube, 3 is a high temperature zone, 4 is a low temperature zone, 5 is a crystal, and 6 is a melt;

[0021] Figure 2 is a photograph of the PIT single crystal prepared in Example 1;

[0022] Figure 3 is a transmittance curve of a 6 mm thick double-sided polished wafer cut at 7 different positions of the PIT single crystal prepared in Example 1;

[0023] Figure 4 This is an absorption curve diagram of a 6 mm thick double-sided polished wafer cut from 6 different positions of the PIT single crystal prepared in Example 1. DETAILED DESCRIPTION

[0024] The beneficial effects of the present invention are verified by the following examples.

[0025] Embodiment 1: The method of reducing the influence of gravity to grow low optical absorption and high uniformity InPbTe single crystals in this embodiment is carried out according to the following steps:

[0026] 1. In an inert atmosphere glove box, weigh 28.617 g of powdered metal element lead, 95.149 g of powdered metal element indium, 176.233 g of powdered metal element tellurium according to the stoichiometric ratio of Pb:In:Te of 1:6:10, and weigh an additional 30 g of powdered In2Te3;

[0027] 2. In a glove box, powdered metal elemental lead, powdered metal elemental indium, powdered metal elemental tellurium and additional powdered In2Te3 were mixed and ground evenly in a mortar, placed in a cylindrical crucible, and then the cylindrical crucible was placed in a quartz tube with a diameter of 12 mm. 5.00 g of elemental Te was added to the quartz tube, and the quartz tube was evacuated to 10 -4 pa, and then use hydrogen-oxygen flame to melt and seal the quartz tube;

[0028] 3. Heating for solid phase reaction: the sealed quartz tube is placed in an inclined single temperature zone tube furnace with an inclination angle of 10°, and then the temperature is raised to 800°C at a rate of 20°C / h and maintained for 100 hours, followed by 3 temperature oscillations within the range of 600-900°C. Each time the temperature oscillates, the temperature is first lowered to 600°C at a rate of 10-20°C / h, and then raised to 900°C at a rate of 10-20°C / h and maintained for 20 hours, completing one oscillation. After the temperature oscillation, the temperature is cooled to room temperature at a rate of 30°C / h to obtain PIT polycrystals, and the PIT polycrystals are placed in a mortar and crushed to obtain powdered PIT polycrystals;

[0029] Fourth, the powdered PIT polycrystalline material prepared in step 3 is loaded into a pyrolytic boron nitride crucible with a seed well, and then the pyrolytic boron nitride crucible is placed in a quartz tube for vacuum sealing; the quartz tube is placed in a multi-temperature zone horizontal crystal growth furnace and fixed, and the seed well of the pyrolytic boron nitride crucible is located in the low temperature zone. The schematic diagram of the dual-temperature zone synthesis is shown in FIG. Figure 1 As shown; the multi-temperature zone horizontal crystal growth furnace is heated so that the temperature of the high temperature zone in the furnace is rapidly heated to 700°C at a rate of 40°C / h, and the temperature of the low temperature zone is rapidly heated to 670°C at a rate of 40°C / h. The temperature field in the gradient zone is 2°C / cm. The temperature is kept for 100 hours to make the polycrystalline raw material fully uniform; then the temperature is reduced at a rate of 0.03°C / h. After the temperature in the high temperature zone is 650°C, it is cooled to room temperature at a rate of 50°C / h to obtain a PIT single crystal.

[0030] The photo of the PIT single crystal prepared in Example 1 is shown in Figure 2 As shown, from Figure 2 It can be seen that the PIT single crystal has no cracks and is of good quality.

[0031] The equal diameter part of the PIT single crystal prepared in Example 1 is divided into 7 different positions from the beginning to the end. Each position is cut into wafers, which are recorded as S1, S2, S3, S4, S5, S6, and S7. They are double-sided polished to a thickness of 6 mm. The transmission curve of each wafer is tested as shown in FIG. Figure 3 As shown, from Figure 3 It can be seen that the PIT single crystal has high optical transmittance in areas with better crystallinity. The transmittance of a 6mm thick double-sided polished wafer is close to 60% in the 2-3μm band, and there is no obvious difference in optical transmittance in different parts.

[0032] The absorption curves of the 6 mm thick double-sided polished wafer at different positions of the PIT single crystal prepared in Example 1 are as follows: Figure 4 As shown, from Figure 4 It can be seen that the optical absorption at 2.09 μm is less than 0.11 cm -1 , which is conducive to using 2.09μm laser to pump output mid-infrared and far-infrared lasers.

Claims

1. A method for reducing the influence of gravity on the growth of low optical absorption and high uniformity indium lead telluride single crystals, characterized in that The method proceeds as follows:

1. In an inert atmosphere glove box, weigh Pb source, In source and Te source according to the stoichiometric ratio of Pb:In:Te of 1:6:10, and weigh additional In2Te3 according to 1% to 10% of the total mass of Pb source, In source and Te source; 2. Place the Pb source, In source, Te source and additional In2Te3 in a cylindrical crucible, then place the cylindrical crucible in a quartz tube, add 0.01-10.00g of elemental Te into the quartz tube, use a molecular pump to evacuate the quartz tube to a vacuum state, and then use a hydrogen-oxygen flame to melt and seal the quartz tube; 3. Heating for solid phase reaction: The sealed quartz tube is placed in an inclined single temperature zone tube furnace with an inclination angle of 0.1° to 30°, and then heated to 750 to 850°C at a rate of 5 to 50°C / h and maintained for 100 hours, and then the temperature is oscillated within the range of 600 to 900°C. After 1 to 10 temperature oscillations, the temperature is cooled to room temperature at a rate of 10 to 50°C / h to obtain PIT polycrystals; 4. Load the PIT polycrystalline material prepared in step 3 into a pyrolytic boron nitride crucible with a seed well, and then place the pyrolytic boron nitride crucible into a quartz tube for vacuum sealing; place the quartz tube into a multi-temperature zone horizontal crystal growth furnace and fix it, and the seed well of the pyrolytic boron nitride crucible is located in the low temperature zone; heat the multi-temperature zone horizontal crystal growth furnace, so that the temperature of the high temperature zone in the furnace is rapidly increased to 700-710°C at a rate of 5-50°C / h, and the temperature of the low temperature zone is rapidly increased to 660-670°C at a rate of 5-50°C / h, the temperature field in the gradient zone is 1-2°C / cm, and the polycrystalline raw material is kept warm for 50-100h to fully homogenize; then cool down at a rate of 0.01-0.1°C / h, and after cooling down to the high temperature zone below 650°C, cool down to room temperature at a rate of 20-50°C / h to obtain a PIT single crystal.

2. The method for growing low optical absorption and high uniformity InPbTe single crystals by reducing the influence of gravity according to claim 1, characterized in that: The Pb source described in step 1 is bulk metallic lead, powdered metallic lead, beaded metallic lead or lead telluride compound.

3. A method for growing low optical absorption and high uniformity InPbTe single crystals by reducing the influence of gravity according to claim 1 or 2, characterized in that: The In source described in step 1 is bulk metal element indium, powdered metal element indium, beaded metal element indium or indium tritelluride compound.

4. A method for growing low optical absorption and high uniformity InPbTe single crystals by reducing the influence of gravity according to claim 1 or 2, characterized in that: The Te source described in step 1 is bulk single crystal tellurium, powdered metal tellurium or beaded metal tellurium.

5. A method for growing low optical absorption and high uniformity InPbTe single crystals by reducing the influence of gravity according to claim 1 or 2, characterized in that: The crucible in step 2 is made of carbon-coated quartz, high-purity corundum, high-purity graphite or high-purity pyrolytic boron nitride.

6. A method for growing low optical absorption and high uniformity InPbTe single crystals by reducing the influence of gravity according to claim 1 or 2, characterized in that: The vacuum state described in step 2 is to vacuum to 10 -4 Below Pa.

7. A method for growing low optical absorption and high uniformity InPbTe single crystals by reducing the influence of gravity according to claim 1 or 2, characterized in that: The specific operation of temperature oscillation within the range of 600-900°C described in step 3 is to first reduce the temperature to 600°C at a cooling rate of 10-20°C / h, and then increase the temperature to 900°C at a heating rate of 10-20°C / h and maintain for 20 hours to complete one oscillation.

8. A method for growing low optical absorption and high uniformity InPbTe single crystals by reducing the influence of gravity according to claim 1 or 2, characterized in that: The holding time for fully homogenizing the polycrystalline raw material in step 4 is 80 to 100 hours.

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