CN102168299B - Method for growing phosphorus-silicon-cadmium single crystal - Google Patents

Abstract

The invention relates to a single crystal growth method of phosphorus, silicon, and cadmium. Si:Cd:P = 1:1:2-2.05 is used to synthesize phosphorus, silicon, and cadmium polycrystalline materials, and the crucible descending furnace is used to grow by spontaneous nucleation growth method or directional seed crystal growth method. The steps include: directly loading the cadmium phosphorus silicon polycrystalline material into the crucible, or adding seed crystals and then loading into the crucible; placing the crucible into a quartz tube, and sealing the quartz tube after vacuuming; loading the quartz tube into the crucible to lower In the furnace; heat up, crucible down, and finally cool down. The method of the invention can prepare high-purity, high-quality phosphorus-silicon-cadmium single crystal.

Description

Growth method of cadmium phosphorus silicon cadmium single crystal

technical field

The invention relates to the preparation of an infrared nonlinear optical material cadmium-phosphorus-silicon single crystal, in particular to a growth method for a cadmium-phosphorus-silicon single crystal.

Background technique

Mid-to-far infrared lasers have many applications in military and civilian fields. Using infrared nonlinear optical crystals for frequency conversion is one of the effective methods to generate continuously tunable mid- and far-infrared lasers. At present, the widely studied infrared nonlinear optical crystals include phosphorous germanium zinc, sulfur gallium silver, selenium gallium silver and so on. Phosphorus germanium zinc has excellent nonlinear optical properties and thermal properties, which can meet the requirements of generating high-power mid-infrared lasers. However, due to the large defect absorption of phosphorus germanium zinc at about 1 μm, it cannot be used in a wider range of about 1 μm. For fundamental frequency optical pumping, the pump source is severely limited. However, the nonlinear optical coefficient and thermal conductivity of silver gallium sulfide and silver gallium selenide are low, which cannot meet the output requirements of high-power mid- and far-infrared lasers.

Cadmium phosphorus silicon, chemical formula CdSiP ₂ , thermal conductivity 13.6Wm ^-1 K ^-1 , specific heat 0.446Jg ^-1 K ^-1 , light transmission range 530nm-10μm, band gap 2.2-2.4eV, it is the current Some infrared materials with the largest nonlinear coefficient that can be pumped by a laser of about 1 μm have a d ₃₆ as high as 84pm/V. CdSi single crystal can be pumped with 1064nm laser to generate 6-8μm infrared laser, and can achieve non-critical phase matching when outputting 6μm laser, and it can also use 1.5μm laser pump to realize 3-5μm infrared tunable output of the laser. The large nonlinear coefficient, high thermal conductivity and wide bandgap of cadmium phosphorus silicon crystals make them a promising method for generating high-power mid-to-far infrared lasers that can be pumped by more mature lasers of about 1 μm. Nonlinear Optical Materials.

However, the melting point of cadmium phosphosilicate crystal is as high as 1133°C, and its saturated decomposition pressure is as high as 22atm near the melting point, and cadmium phosphosilicate will react with quartz at high temperature, which will easily lead to the explosion of the crucible. Such a high temperature and decomposition pressure make polycrystalline synthesis and single crystal growth of cadmium phosphorus silicon very difficult. A method for growing cadmium phosphorus silicon cadmium single crystals in a transparent horizontal gradient condensation furnace has been reported in the literature, see Kevin T.Zawilski, Peter G.Schunemann, etc., Growth and characterization of large CdSiP ₂ single crystals, Journal of Crystal Growth, 2010, 312:1127–1132. However, this method has disadvantages such as high requirements for equipment, difficulty in spontaneous nucleation and growth, difficulty in maintaining flat interface growth control, and serious vapor convection above the melt. The grown crystals are prone to crystal defects such as twins and component deviations from the stoichiometric ratio.

Contents of the invention

Aiming at the difficulties in the synthesis and growth of cadmium phosphorus silicon, the invention provides a growth method of cadmium phosphorus silicon single crystal.

The technical gist of the invention is to synthesize cadmium-phosphorous-silicon polycrystalline material by adopting a single temperature zone or double-temperature zones, and to grow cadmium-phosphorus-silicon single crystal by using a crucible-down furnace.

Technical scheme of the present invention is as follows:

A method for growing phosphorus-silicon-cadmium single crystals, using simple raw material silicon:cadmium:phosphorus to synthesize phosphorus-silicon-cadmium polycrystalline material in a molar ratio of 1:1:2-2.05, using a crucible drop furnace, through spontaneous nucleation growth method or seed Phosphorous silicon cadmium single crystal was prepared by crystal growth method;

The spontaneous nucleation and growth method is as follows: the phosphorus, silicon and cadmium polycrystalline material is loaded into a growth crucible, the growth crucible is loaded into a quartz tube, and the quartz tube is sealed after vacuuming to below 2×10 ^-4 Pa; Put the quartz tube of phosphorus, silicon and cadmium polycrystalline material into the crucible descending furnace, so that the crucible is located in the high temperature zone; make the crucible descend the furnace to heat up, and the temperature in the high temperature zone is kept higher than 1140°C, and the temperature gradient in the gradient zone is between 3 and 20°C /cm, the temperature in the low-temperature zone is kept at 1050-1100°C; after 10-20 hours of heat preservation in the high-temperature zone, the crucible is lowered at a rate of 0.1-4mm/h; after the crucible is lowered to the low-temperature zone, it stops falling; the crucible is cooled, Decrease to 950-1030°C at 1-10°C/h, then drop to 25-35°C at 10-20°C/h.

The seed crystal growth method is: put the cadmium phosphorus silicon seed crystal into the seed crystal bag of the growth crucible, put the cadmium phosphorus silicon polycrystalline material into the growth crucible, put the growth crucible into the quartz tube, and evacuate to 2 Seal the quartz tube after ×10 ^-4 Pa; put the quartz tube with the seed crystal and phosphorus, silicon and cadmium polycrystalline material into the crucible lowering furnace, so that the crucible is located in the low temperature zone; raise the temperature of the crucible lowering furnace, and control the temperature of the crucible lowering furnace Temperature, the temperature in the high temperature zone is higher than 1140°C, the temperature gradient in the gradient zone is 3-20°C/cm, the temperature in the low temperature zone is kept at 1050-1100°C, and the crucible is slowly raised to the temperature where the seed crystal and the polycrystal are in contact Not lower than the melting point of cadmium phosphorus silicon cadmium 1130 ℃, the temperature of the bottom of the seed crystal is not higher than 1130 ℃, keep the crucible at this position for 10 ~ 20h and then start to drop, the rate of drop is 0.1 ~ 4mm/h; drop the crucible to the low temperature zone Then stop the drop; cool the crucible to 950-1030°C at 1-10°C/h, and then drop to 25-35°C at 10-20°C/h.

According to the present invention, the crucible can rotate around its axis while descending, and the rotation mode adopts trapezoidal wave, triangular wave or rectangular wave, etc. known to those skilled in the art.

Preferably in the present invention, while the crucible is descending, the crucible rotates in a trapezoidal wave mode. In one rotation cycle, the acceleration time is 30s, the constant speed time is 30s, the maximum constant speed is 30rad/min, the deceleration time is 30s, and is reduced to 0rad After /min, perform the same reverse acceleration, constant speed and deceleration, and then enter the next rotation cycle.

According to the present invention, preferably, the growth crucible is graphite boat, boron nitride boat, quartz boat coated with carbon film, quartz boat coated with pyrolytic boron nitride coating, graphite coated with pyrolytic boron nitride coating Boat.

According to the present invention, preferably, when the temperature of the crucible lowering furnace is raised, the temperature in the high temperature zone is kept at 1145-1165°C, more preferably the temperature in the high-temperature zone is kept at 1150-1160°C.

According to the present invention, preferably, the temperature rise rate of the crucible descending furnace is controlled at 50-100°C/h, including the spontaneous nucleation growth method and the seed crystal growth method, all need to control the temperature rise rate of the crucible descending furnace in the same way, the purpose It is to prevent the rapid increase in temperature from causing the pressure in the crucible to burst and burst the quartz tube.

According to the present invention, preferably, during the growth process of cadmium phosphorus silicon single crystal, the temperature gradient in the temperature gradient zone is controlled at 5-15° C./cm, and the descending speed of the crucible is controlled at 0.5-3 mm/h. The purpose is to not only form single crystal growth and avoid the generation of crystal defects such as dislocations and twins, but also ensure a certain single crystal growth efficiency.

According to the present invention, the cooling rate of the crucible is controlled from the growth temperature to 1000 °C at a rate of 10 °C/h or less, and then to room temperature at a rate of 20 °C/h or less, in order to prevent the single crystal from being damaged during the cooling process. Excessive thermal stress leads to cracks or complete cracks in the crystal, which also ensures that the growth cycle is shortened and the growth efficiency is improved. Preferably, the cooling of the crucible is to first cool down to 1000-1030°C at 6-10°C/h, then cool down to 950°C at 5°C/h, and then cool down to 650-800°C at 20°C/h, Then cool down to 30°C at 10°C/h.

The synthesis of the cadmium phosphosilicate polycrystalline material used for the growth of cadmium silicon phosphate single crystal in the present invention can adopt the existing technology in this field. The present invention provides the preferred scheme for the synthesis of the following cadmium phosphorus, silicon, and cadmium polycrystalline materials:

The single-temperature-zone synthetic method of phosphorus-silicon-cadmium polycrystalline material, step is as follows: (1) three kinds of elemental raw materials of phosphorus, silicon, cadmium that purity is 99.999% press silicon: cadmium: the mole of phosphorus=1:1:2～2.05 (2) Put the synthetic crucible into the quartz tube, vacuumize to below 2× ^10-4 Pa, and then seal the quartz tube; (3) Put the quartz tube into the single-temperature zone synthetic furnace, Raise the temperature of the single temperature zone synthesis furnace from room temperature to 350-750°C at a heating rate of less than 50°C/h, then keep at this temperature for 20-25 hours, and then raise the temperature to 1140-1160°C at a heating rate of less than 20°C/h, Keep it warm for 20-35 hours, cool down to room temperature, and open the synthesis crucible to obtain polycrystalline material of phosphorus, silicon and cadmium.

The above single temperature zone synthesis furnace is preferably a vertical tubular resistance furnace.

The double-temperature zone synthetic method of phosphorus-silicon-cadmium polycrystalline material, step is as follows: 1) three kinds of elemental raw materials of phosphorus, silicon, cadmium that purity is 99.999% press silicon: cadmium: the mol ratio of phosphorus=1:1:2～2.05 For ingredients, put phosphorus into one end of the quartz tube, put silicon and cadmium into the synthesis boat and load the other end of the quartz tube, vacuumize the quartz tube to below 2×10 ^-4 Pa and seal it; 2) put the quartz tube One end that phosphorus is housed is placed in the low-temperature zone of double-temperature zone synthesis furnace, and one end that the synthetic boat of silicon and cadmium is housed is placed in the high-temperature zone of double-temperature zone synthesis furnace; 3) the low-temperature zone of double-temperature zone furnace is changed from room temperature Raise the temperature to 450-750°C with a heating rate of less than 50°C/h, keep it for 10-15 hours, then raise the temperature to 1160°C with a heating rate of less than 20°C/h, and keep it at 1160°C for 10-15 hours; at the same time, put the double The high temperature zone of the temperature zone synthesis furnace is raised from room temperature to 600-1000°C at a heating rate of less than 50°C/h, kept for 10-15 hours, and then raised to 1150°C at a heating rate of less than 200°C/h, kept for 10-15 hours; 3) At the same time, the two temperature zones of the dual-temperature zone furnace are lowered to room temperature, and the quartz tube is opened to obtain the phosphorus-silicon-cadmium polycrystalline material.

The falling crucible furnace used for the growth of cadmium phosphorus silicon cadmium single crystal in the present invention is also called vertical Bridgman furnace. The prior art can be used, for example, the multi-component infrared crystal growth device provided by CN201224776Y (CN200820025995.7).

Compared with prior art, the excellent effect of the present invention is as follows:

1. The method of the present invention adopts a vertical furnace body for crystal growth, which can conveniently carry out accelerated crucible rotation control, has the advantages of easy control of melt convection and suppression of steam convection above the melt, and can be prepared under a larger temperature gradient. Stoichiometric cadmium phosphorus silicon single crystal.

2. When the spontaneous nucleation technology is used for cadmium phosphorus silicon single crystal growth, it is easy to form a single crystal nucleus at the beginning of growth, and it is easy to maintain flat interface growth during the growth process, which can ensure high single crystal yield.

3. When the directional seed crystal method is used for cadmium phosphorus silicon single crystal growth, high-quality cadmium phosphorus silicon cadmium single crystal without crystal defects such as cracks and twins can be prepared.

Description of drawings

Figure 1 Comparison of the XRD (upper) and the standard diffraction spectrum (lower) of the cadmium phosphorus silicon polycrystalline powder prepared in Example 1.

Fig. 2 Axial temperature field curve of crucible descending furnace. The abscissa is the temperature, and the ordinate is the distance from the crucible to the top of the furnace.

Photo of cadmium phosphorus silicon cadmium single crystal grown in embodiment 1 of Fig. 3 .

The single crystal rocking curve of the (112) plane of the phosphorous silicon cadmium single crystal grown in Fig. 4 Example 1.

Detailed ways

The present invention will be further described below in conjunction with the embodiments and accompanying drawings, but not limited thereto. The falling crucible furnace used for the growth of cadmium phosphorus silicon cadmium single crystal in the embodiment adopts the prior art CN201224776Y, and its axial temperature field curve is shown in FIG. 2 .

The vertical tubular resistance furnace and dual-temperature zone synthesis furnace used in the synthesis of phosphorus, silicon and cadmium polycrystalline materials in the examples are all prior art in the field of crystal growth.

Embodiment 1, single temperature zone synthesis of cadmium phosphorus silicon polycrystalline material and single crystal growth of cadmium phosphorus silicon cadmium, the steps are as follows:

1. Preparation of cadmium phosphorus silicon polycrystalline material

Put three elemental elements with a purity of 99.999% into a graphite crucible at a ratio of silicon: cadmium: phosphorus = 1:1:2, put the graphite crucible into a quartz tube, vacuumize to 2×10 ^-4 Pa, and seal Quartz tube. Put the quartz tube into a vertical tubular resistance furnace, raise the temperature of the resistance furnace from room temperature to 350°C at a rate of 30°C/h, and keep it at 350°C for 10-30h. Then the temperature was raised from 350°C to 1150°C at a heating rate of 10°C/h, kept at 1150°C for 20 hours, and then lowered to room temperature. Open the quartz tube, and what is obtained in the graphite crucible is the polycrystalline material of phosphorus, silicon and cadmium. The XRD spectrogram of the obtained cadmium phosphorus silicon polycrystalline material is as shown in Figure 1, and each peak in the figure corresponds to each peak of the standard diffraction pattern of cadmium phosphorus silicon (PDF65-2725), indicating that what is synthesized is highly pure phosphorus Silicon cadmium polycrystalline material.

2. Phosphorous silicon cadmium single crystal growth

Put the phospho-silicon-cadmium polycrystalline material synthesized above into a boron nitride crucible, put the boron nitride crucible into a quartz tube, vacuumize to 2×10 ^-4 Pa, and seal the quartz tube with a hydrogen-oxygen flame. Put the quartz tube containing phosphorus, silicon and cadmium polycrystalline material into the crucible descending furnace, place the crucible in the high temperature zone, raise the temperature of the crucible descending furnace, keep the temperature in the high temperature zone at 1150 ° C, and the temperature gradient in the gradient zone at 5 ° C / cm, the temperature in the low-temperature zone is kept at 1100°C; after 19 hours of heat preservation in the high-temperature zone, the crucible starts to descend at a rate of 1-3mm/h; while descending, the crucible rotates in a trapezoidal wave manner, and within one rotation cycle, the acceleration time The constant speed is 30s, the constant speed time is 30s, the maximum constant speed is 30rad/min, the deceleration time is 30s, after reducing to 0rad/min, the same reverse acceleration, constant speed and deceleration are performed, and then enter the next rotation cycle; the crucible is lowered After reaching the low temperature zone, stop the descent and rotation, then drop to 1000°C at 4°C/h, and then drop to room temperature at 20°C/h.

The photo of the obtained phosphorous silicon cadmium single crystal is shown in Figure 3, and the single crystal rocking curve of the (112) plane after directional cutting to it is shown in Figure 4. good.

Embodiment 2, single-temperature-zone synthesis of cadmium-phosphorus-silicon polycrystalline material and growth of cadmium-phosphorus-silicon single crystal, the steps are as follows:

1, the synthesis of phosphorus-silicon-cadmium polycrystalline material, as described in embodiment 1 step 1, the difference is: in the synthesis of phosphorus-silicon-cadmium polycrystalline material, three kinds of elemental elements are by silicon: cadmium: phosphorus=1: 1: The ratio of 2.02 is packed in the graphite crucible, and other steps and parameters are all the same as in Example 1.

2. Phosphorous silicon cadmium single crystal growth

Put the cadmium phosphorus silicon seed crystal into the seed bag of the boron nitride growth crucible, then put the cadmium phosphorus silicon polycrystalline material synthesized in step 1 into the boron nitride growth crucible, and put the boron nitride growth crucible into In the quartz tube, after vacuuming to 2×10 ^-4 Pa, seal the quartz tube with an oxyhydrogen flame; put the quartz tube with the seed crystal and phosphorus, silicon, cadmium polycrystalline material into the crucible descending furnace; heat up the crucible and descend the furnace, Control the temperature of the crucible to lower the temperature of the high-temperature zone of the furnace to 1150°C, the temperature gradient in the gradient zone to be 5°C/cm, and the temperature in the low-temperature zone to remain at 1100°C; slowly raise the crucible so that the temperature at the contact point between the seed crystal and the polycrystal is not high. It is lower than the melting point of cadmium phosphorus silicon 1130℃, so that the temperature at the bottom of the seed crystal is not higher than 1130℃. After 18 hours of heat preservation, the crucible is lowered at a rate of 1 to 3mm/h; while falling, the crucible rotates in a trapezoidal wave. In one rotation cycle, the acceleration time is 30s, the constant speed time is 30s, the maximum constant speed is 30rad/min, the deceleration time is 30s, after reducing to 0rad/min, reverse acceleration, constant speed and deceleration, and then enter the next cycle ; Lower the crucible to the low temperature zone and then stop falling, then drop to 1000°C at 5°C/h, then drop to 700°C at 20°C/h, and drop to 30°C at 10°C/h.

Embodiment 3, as described in Example 1, the difference is: in step 2, the temperature in the high temperature zone is kept at 1160°C, the temperature gradient in the gradient zone is at 8°C/cm, and the temperature in the low temperature zone is kept at 1090°C; After 30 hours of heat preservation in the high temperature zone, the crucible was lowered.

Embodiment 4, as described in Example 1, the difference is: in step 2, the temperature in the high temperature zone is kept at 1160°C, the temperature gradient in the gradient zone is at 12°C/cm, and the temperature in the low temperature zone is kept at 1070°C; After 30 hours of heat preservation in the high temperature zone, the crucible was lowered.

Example 5, as described in Example 1, the difference is: in step 2, the temperature in the high temperature zone is kept at 1160°C, the temperature gradient in the gradient zone is at 15°C/cm, and the temperature in the low temperature zone is kept at 1060°C; After 25 hours of heat preservation in the high temperature zone, the crucible was lowered.

Embodiment 6. As described in Embodiment 1, the difference is that in step 2, the growth crucible used is a graphite crucible.

Embodiment 7. As described in Embodiment 1, the difference is that in step 2, the growth crucible used is a carbon-coated quartz crucible.

Example 8, as described in Example 1, the difference is: in step 2, the crucible stops falling after descending to the low temperature zone, then drops to 1000°C at 3°C/h, and then drops to room temperature at 15°C/h.

Example 9, as described in Example 2, the difference is: in step 2, the temperature in the high temperature zone is kept at 1160°C, the temperature gradient in the gradient zone is at 8°C/cm, and the temperature in the low temperature zone is kept at 1080°C; After 24 hours of heat preservation in the high temperature zone, the crucible was lowered.

Example 10, as described in Example 2, the difference is: in step 2, the temperature in the high temperature zone is kept at 1160°C, the temperature gradient in the gradient zone is at 12°C/cm, and the temperature in the low temperature zone is kept at 1060°C; After 20 hours of heat preservation in the high temperature zone, the crucible was lowered.

Embodiment 11. As described in Embodiment 1, the difference is that in step 2, the growth crucible used is a graphite crucible.

Example 13, as described in Example 1, the difference is: in step 2, the crucible stops falling after descending to the low temperature zone, then drops to 1000°C at 2°C/h, and then drops to room temperature at 15°C/h.

Claims (1)

1. A growth method of phosphorus-silicon-cadmium single crystal comprises the following steps of using simple substance raw material silicon: cadmium: phosphorus is added according to the weight ratio of 1: 1: synthesizing a phosphorus-silicon-cadmium polycrystal material according to the molar ratio of 2-2.05, and preparing a phosphorus-silicon-cadmium monocrystal by adopting a crucible descending furnace through a spontaneous nucleation growth method or a seed crystal growth method;

the spontaneous nucleation growth method comprises the following steps: loading the polycrystal material of phosphorus, silicon and cadmium into a growth crucible, loading the growth crucible into a quartz tube, and vacuumizing to 2 x 10^-4Sealing the quartz tube after Pa; putting the quartz tube filled with the phosphorus-silicon-cadmium polycrystal material into a crucible descending furnace, and enabling a crucible to be positioned at a high-temperature area; raising the temperature of the crucible lowering furnaceThe temperature of the high-temperature region is kept at 1145-1165 ℃, the temperature gradient of the gradient region is 3-20 ℃/cm, and the temperature of the low-temperature region is kept at 1050-; after the heat preservation is carried out in the high-temperature area for 10-20 hours, the crucible is started to descend at the descending speed of 0.1-4 mm/h, and the crucible is stopped to descend after descending to the low-temperature area; cooling the crucible to 950-1030 ℃ at a speed of 1-10 ℃/h, and then cooling to 25-35 ℃ at a speed of 10-20 ℃/h;

the seed crystal growth method comprises the following steps: loading the P-Si-Cd seed crystal into the seed crystal bag of growth crucible, loading P-Si-Cd polycrystal material into the growth crucible, loading the growth crucible into quartz tube, and vacuumizing to 2 × 10^-4Sealing the quartz tube after Pa; putting a quartz tube filled with seed crystals and a phosphorus-silicon-cadmium polycrystal material into a crucible descending furnace, and enabling a crucible to be positioned in a low-temperature region; raising the temperature of the crucible descending furnace, controlling the temperature of the crucible descending furnace, keeping the temperature of a high-temperature region at 1150-1160 ℃, the temperature gradient of a gradient region at 3-20 ℃/cm, keeping the temperature of a low-temperature region at 1050-; cooling the crucible to 950-1030 ℃ at a speed of 1-10 ℃/h, and then cooling to 25-35 ℃ at a speed of 10-20 ℃/h;

the temperature rising speed of the crucible descending furnace is controlled to be 50-100 ℃/h;

the phosphorus-silicon-cadmium polycrystal material is synthesized by the following steps: (1) three elementary substance raw materials of phosphorus, silicon and cadmium with the purity of 99.999 percent are as follows: cadmium: phosphorus = 1: 1: 2-2.05 mol ratio and placing into a synthesis crucible; (2) placing the synthetic crucible into a quartz tube, and vacuumizing to 2 × 10^-4Sealing the quartz tube after Pa is lower than Pa; (3) putting the quartz tube into a single-temperature-zone synthesis furnace, heating the single-temperature-zone synthesis furnace from room temperature to 350-750 ℃ at a heating rate of less than 50 ℃/h, then preserving heat at the temperature for 20-25 h, heating to 1140-1160 ℃ at a heating rate of less than 20 ℃/h, preserving heat for 20-35 h, cooling to room temperature, and opening a synthesis crucible to obtain the phosphorus-silicon-cadmium polycrystal material; or,

the phosphorus-silicon-cadmium polycrystal material is synthesized by the following stepsThe following steps: 1) three elementary substance raw materials of phosphorus, silicon and cadmium with the purity of 99.999 percent are as follows: cadmium: phosphorus = 1: 1: 2-2.02 mol ratio, loading phosphorus into one end of a quartz tube, loading silicon and cadmium into the other end of the quartz tube in a synthesis boat, and vacuumizing the quartz tube to 2 x 10^-4Sealing after Pa; 2) one end of the quartz tube filled with phosphorus is arranged in a low-temperature area of the double-temperature-area synthesis furnace, and one end of the synthesis boat filled with silicon and cadmium is arranged in a high-temperature area of the double-temperature-area synthesis furnace; 3) heating the low-temperature region of the dual-temperature-region furnace from room temperature to 450-750 ℃ at a heating rate of less than 50 ℃/h, preserving heat for 10-15 h, then heating to 1160 ℃ at a heating rate of less than 20 ℃/h, and preserving heat for 10-15 h at 1160 ℃; meanwhile, heating the high-temperature area of the double-temperature-area synthesis furnace from room temperature to 600-1000 ℃ at a heating rate of less than 50 ℃/h, preserving heat for 10-15 h, then heating to 1150 ℃ at a heating rate of less than 200 ℃/h, and preserving heat for 10-15 h; 4) simultaneously, cooling the two temperature areas of the double-temperature-area furnace to room temperature, and opening the quartz tube to obtain the phosphorus-silicon-cadmium polycrystal material.

2. The method of claim 1, wherein the growth crucible is made of graphite boat, boron nitride boat, carbon-coated quartz boat or pyrolytic boron nitride coated quartz boat.

3. A method for growing single crystal of cadmium silicon phosphate as claimed in claim 1, wherein the material of the growth crucible is graphite boat coated with pyrolytic boron nitride.

4. A method for growing P-Si-Cd monocrystal as claimed in claim 1, wherein the temperature gradient of the gradient region is controlled to be 5-15 ℃/cm during the growth of P-Si-Cd monocrystal.

5. A method for growing a cadmium silicon phosphate single crystal according to claim 1, wherein the lowering rate of the crucible is controlled to be 0.5 to 3 mm/h.

6. A method for growing a cadmium silicon phosphate single crystal according to claim 1, wherein the crucible is rotated about its axis while being lowered in a trapezoidal wave, triangular wave or rectangular wave manner.

7. A method for growing P-Si-Cd as claimed in claim 6, wherein the crucible is rotated in a trapezoidal wave manner, and in one rotation cycle, the acceleration time is 30s, the constant speed time is 30s, the maximum constant rotation speed is 30rad/min, the deceleration time is 30s, and after reducing to 0rad/min, the same reverse acceleration, constant speed and deceleration are performed, and then the next rotation cycle is proceeded.

8. The method as claimed in claim 1, wherein the temperature of the crucible is lowered by 6-10 ℃/h to 1000-1030 ℃, then by 5 ℃/h to 950 ℃, then by 20 ℃/h to 650-800 ℃, and then by 10 ℃/h to 30 ℃.

Images