Device for preparing large-size polycrystalline zinc selenide and growth method

Abstract

The invention discloses a device for preparing large-size polycrystalline zinc selenide and a growth method, and belongs to the technical field of infrared materials.The device comprises a chemical vapor deposition furnace assembly, a graphite tower assembly and a dust collection assembly.The large-size polycrystalline zinc selenide is prepared by optimizing deposition process parameters and combining a multi-crucible continuous feeding mechanism; high-quality zinc selenide crystals with the diameter and the thickness reaching the standard are successfully prepared, the strict requirements of downstream high-end devices for the size and the thickness of materials are met, efficient collection and cleaning of by-product zinc selenide dust are achieved by adopting a three-parallel-connection dust collector structure and a pulse electromagnetic valve purging technology, the pressure rise rate of a system is remarkably reduced, and the service life of the system is prolonged. And blockage and pressure fluctuation caused by dust accumulation are avoided, and a continuous and stable low-pressure environment is provided for crystal growth.

Description

Technical Field

[0001] This invention relates to the field of infrared materials technology, specifically to an apparatus and growth method for preparing large-size polycrystalline zinc selenide. Background Technology

[0002] Infrared zinc selenide crystals are approximately 65 μm in size and exhibit excellent light transmittance in the 0.6-16 μm range. Due to its superior physicochemical properties, it exhibits virtually no impurity absorption and extremely low scattering loss. Its minimal absorption at a wavelength of 10.6 μm makes it the preferred material for optical devices in CO2 laser systems, and it holds significant application potential in blue light semiconductor light-emitting devices, nonlinear optoelectronic devices, nuclear radiation detectors, and near-ultraviolet-visible light detectors. With technological advancements, downstream applications demand increasingly larger sizes of high-quality zinc selenide, with diameters exceeding 200 mm and thicknesses exceeding 50 mm. The primary equipment for preparing high-quality zinc selenide is a chemical vapor deposition (CVD) furnace. CVD uses high-purity zinc and high-purity hydrogen selenide gas as raw materials, high-purity inert argon gas as the carrier gas, and a graphite substrate as the matrix. A chemical reaction occurs within the CVD furnace to obtain zinc selenide blanks.

[0003] Currently, chemical vapor deposition furnaces typically employ a single crucible, single deposition chamber, and graphite tower. Because the zinc charge in a single crucible is limited, growth ends once the zinc evaporates, resulting in the inability to obtain large-sized, thick-grained zinc selenide. Furthermore, even with sufficient zinc feedstock, the furnace outlet and dust collection system become clogged due to the large accumulation of zinc selenide dust, a byproduct of the reaction process, causing a rapid increase in furnace pressure. High-quality zinc selenide growth requires a continuous and stable environment; increased furnace pressure and pressure buildup in the graphite tower signify failed zinc selenide crystal growth and furnace shutdown. To address these issues, this invention patents a device and growth method for producing large-sized, thick-grained polycrystalline zinc selenide. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the problems existing in the above and / or the existing apparatus and growth method for preparing large-size polycrystalline zinc selenide, the present invention is proposed.

[0006] Therefore, the purpose of this invention is to provide an apparatus and growth method for preparing large-size polycrystalline zinc selenide. By optimizing deposition process parameters and combining a multi-crucible continuous feeding mechanism, high-quality zinc selenide crystals with both diameter and thickness meeting the requirements can be successfully prepared, satisfying the stringent requirements of downstream high-end devices for material size and thickness. Furthermore, by adopting a three-parallel dust collector structure and pulse solenoid valve purging technology, the byproduct zinc selenide dust is efficiently collected and cleaned, significantly reducing the system pressure rise rate and avoiding blockage and pressure fluctuations caused by dust accumulation, thus providing a continuous and stable low-pressure environment for crystal growth.

[0007] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution: An apparatus for preparing large-size polycrystalline zinc selenide, comprising: A chemical vapor deposition furnace assembly includes a water-cooled furnace body, a lower furnace cover installed at the bottom of the water-cooled furnace body, and an upper furnace cover installed at the top of the water-cooled furnace body. An inlet pipe extends through the bottom of the lower furnace cover. A graphite deposition chamber is installed inside the water-cooled furnace body. The top end of the inlet pipe extends into the water-cooled furnace body and connects to the graphite deposition chamber. A guide pipe is installed at the top of the graphite deposition chamber. The other end of the guide pipe extends out of the side wall of the chemical vapor deposition furnace assembly and is equipped with an outlet. The graphite tower assembly includes a graphite cover plate located inside the water-cooled furnace body and below the graphite deposition chamber, two graphite crucibles symmetrically installed at the bottom of the graphite cover plate, and a graphite deposition chamber base installed at the top of the graphite cover plate, wherein the bottom of the graphite deposition chamber is connected to the top of the graphite deposition chamber base. The dust collection system includes a main dust collector connected to the air outlet, a parallel dust collection system connected to the tail end of the main dust collector, and an exhaust system connected to the tail end of the parallel dust collection system.

[0008] As a preferred embodiment of the apparatus for preparing large-size polycrystalline zinc selenide according to the present invention, the inner wall of the water-cooled furnace body is provided with a furnace body insulation cylinder, the top of the lower furnace cover is provided with a lower furnace cover insulation layer, the bottom of the upper furnace cover is provided with an upper furnace cover insulation layer, the furnace body insulation cylinder, the lower furnace cover insulation layer and the upper furnace cover insulation layer are connected as a whole, and the position of the guide pipe extending out of the side wall of the water-cooled furnace body is wrapped with a gas outlet insulation layer.

[0009] In a preferred embodiment of the apparatus for preparing large-size polycrystalline zinc selenide according to the present invention, a furnace insulation cylinder is provided inside the water-cooled furnace body, a lower heater is provided on the top of the lower furnace cover, an upper thermocouple is provided on the side wall of the water-cooled furnace body corresponding to the position of the graphite deposition chamber, a lower thermocouple is installed on the side wall of the water-cooled furnace body corresponding to the position of the graphite tower assembly, and a first vacuum gauge is installed on the top of the upper furnace cover.

[0010] In a preferred embodiment of the apparatus for preparing large-size polycrystalline zinc selenide according to the present invention, two inlet pipe through holes are symmetrically opened on the top of the graphite cover plate, the inlet pipe through holes are connected to the inlet pipes, and two sets of first zinc vapor outlets are symmetrically opened on the top of the graphite cover plate with the inlet pipe through holes as the center. Each set of first zinc vapor outlets has three outlets and is connected to the graphite crucible below.

[0011] In a preferred embodiment of the apparatus for preparing large-size polycrystalline zinc selenide according to the present invention, a confluence channel is provided at the bottom of the graphite deposition chamber base. Two grooves are symmetrically formed at the bottom of the graphite deposition chamber base with the confluence channel as the center. Each groove is located above the corresponding first zinc vapor outlet and communicates with the first zinc vapor outlet. Three zinc vapor channels are formed on the side wall of the groove and communicate with the confluence channel. A second zinc vapor outlet is formed at the top of the confluence channel. A sealing gasket is installed inside the confluence channel. An air inlet outlet is formed at the bottom of the sealing gasket and communicates with the air inlet through hole.

[0012] In a preferred embodiment of the apparatus for preparing large-size polycrystalline zinc selenide according to the present invention, a first dust collection bin is installed at the bottom of the main dust collector, and the exhaust system includes a dust collection main pipe, a pressure regulating valve installed on the main dust collection main pipe, and a vacuum pump installed on the main dust collection main pipe and located at the tail of the pressure regulating valve.

[0013] In a preferred embodiment of the apparatus for preparing large-size polycrystalline zinc selenide according to the present invention, the parallel dust collection system includes three parallel dust collectors and dust collection branch pipes respectively connected to both ends of each parallel dust collector. The front ends of the three dust collection branch pipes are all connected to the main dust collector, and the rear ends of the three dust collection branch pipes are all connected to the main dust collection pipe. A second dust collection bin is installed at the bottom of each parallel dust collector, and a pulse solenoid valve is installed at the top of each parallel dust collector. A first pneumatic valve and a second vacuum gauge are installed on the body of the dust collection branch pipe located at the front end of the parallel dust collector, and a second pneumatic valve and a third vacuum gauge are installed on the body of the dust collection branch pipe located at the rear end of the parallel dust collector.

[0014] In a preferred embodiment of the apparatus for preparing large-size polycrystalline zinc selenide according to the present invention, a pressure regulating main pipe is installed at the front end of the pressure regulating valve, and three pressure regulating branch pipes extend from the other end of the pressure regulating main pipe. The three pressure regulating branch pipes are respectively connected to three parallel dust collectors, and a third pneumatic valve is installed on the body of each pressure regulating branch pipe.

[0015] The present invention also provides a method for growing large-size polycrystalline zinc selenide, wherein the method uses the apparatus described above for preparing large-size polycrystalline zinc selenide, and includes the following steps: S1. First, complete the dust collection system program settings. When hydrogen selenide gas is introduced into the inlet pipe of the dust collection system, the corresponding flat pressure branch pipe in the uppermost parallel dust collector, the corresponding first pneumatic valve, second pneumatic valve, and flat pressure branch pipe in the middle parallel dust collector, and the corresponding first pneumatic valve, second pneumatic valve, and flat pressure branch pipe in the lower parallel dust collector are simultaneously closed. The upper parallel dust collector is in use, while the middle and lower parallel dust collectors are in standby mode. When the following conditions are met, the parallel dust collectors are switched to use sequentially according to the following conditions: when the pressure difference between the first pneumatic valve and the second pneumatic valve in the middle is greater than 100-1000 Pa, the middle parallel dust collector... The second pneumatic valve opens automatically. After waiting 10-60 seconds, the first pneumatic valve in the middle opens automatically. After waiting 10-60 seconds, the first pneumatic valve at the top closes automatically. After waiting 10-60 seconds, the second pneumatic valve at the top closes automatically. This completes the switching of the upper parallel dust collector to the middle parallel dust collector. Similarly, when the pressure difference of the middle parallel dust collector is greater than 100-1000 Pa, the middle parallel dust collector switches to the lower parallel dust collector. When the pressure difference of the lower parallel dust collector is greater than 100-1000 Pa, the lower parallel dust collector switches to the upper parallel dust collector. The three parallel dust collectors are used in a cyclical manner from top to bottom. S2. After the parallel dust collector is used, zinc selenide powder adheres to the surface of the filter bags inside the parallel dust collector. It is necessary to blow the powder on the filter bags into the second dust collection bucket. Select the parallel dust collector to be blown, click the corresponding pulse solenoid valve to open, and blow according to the following program settings: click the pulse solenoid valve to open, and automatically close it after 10 to 60 seconds of blowing time. After waiting for the zinc selenide powder to stand for 5 to 30 minutes, the corresponding second pneumatic valve will automatically open. When the pressure of the corresponding second vacuum gauge is equal to the pressure of the furnace body, the corresponding second pneumatic valve will automatically close, and the blowing is completed. S3. Install high-purity zinc ingots in the two graphite crucibles, install the graphite tower, gas inlet pipe, and furnace. Connect the furnace body to the gas supply system. Evacuate the chemical vapor deposition furnace to its ultimate vacuum. While evacuating the furnace body to its ultimate vacuum, introduce high-purity argon gas at a rate of 20–80 L / min into the furnace through the gas supply pipe for 30–300 min to clean the gas supply system and furnace body. At room temperature, introduce high-purity argon gas carrying zinc vapor into the crucibles, and introduce argon gas mixed with high-purity hydrogen selenide into the graphite deposition chamber. Maintain a vacuum of 5000–12000 Pa in the furnace body to complete the ventilation. The upper heater and the lower heater heat up simultaneously. The lower heater heats up at a rate of 0.25–2 °C / min until it reaches the zinc evaporation temperature of 660–780 °C. The upper heater heats up at a rate of 0.2–1.5 °C / min until it reaches 720–810 °C. Once the lower heater and the upper heater reach the zinc evaporation temperature and deposition temperature, wait for the zinc material to vaporize and evaporate, thus completing the furnace body heating process. S4. After the upper heater and the lower heater reach the target temperature and remain constant, the zinc evaporation rate in the graphite crucible stabilizes. High-purity hydrogen selenide gas is introduced through the gas inlet pipe. The flow rates of high-purity argon gas carrying zinc vapor, argon gas mixed with high-purity hydrogen selenide, and high-purity hydrogen selenide are adjusted to control the reaction ratio of hydrogen selenide and zinc vapor, and chemical vapor deposition is performed to grow crystals. After the zinc material in one of the graphite crucibles has evaporated completely, the hydrogen selenide gas is stopped. The upper heater and the lower heater are cooled simultaneously. The cooling rate of the lower heater is 0.15-3℃ / min, and the cooling rate of the upper heater is 0.1-2℃ / min. High-quality zinc selenide crystals with a thickness of 50-120mm and a diameter of 100-300mm are obtained after exiting the furnace.

[0016] Compared with existing technologies, by optimizing deposition process parameters and combining a multi-crucible continuous feeding mechanism, high-quality zinc selenide crystals with both diameter and thickness meeting the requirements were successfully prepared, satisfying the stringent requirements of downstream high-end devices for material size and thickness. Furthermore, by adopting a three-parallel dust collector structure and pulse solenoid valve purging technology, the efficient collection and cleaning of by-product zinc selenide dust was achieved, significantly reducing the system pressure rise rate and avoiding blockage and pressure fluctuations caused by dust accumulation, thus providing a continuous and stable low-pressure environment for crystal growth. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is an overall structural diagram of the apparatus for preparing large-size polycrystalline zinc selenide according to the present invention; Figure 2 This is a structural diagram of a chemical vapor deposition furnace component of an apparatus for preparing large-size polycrystalline zinc selenide according to the present invention. Figure 3 This is a structural diagram of the dust collection component of an apparatus for preparing large-size polycrystalline zinc selenide according to the present invention; Figure 4 This invention relates to an apparatus for preparing large-size polycrystalline zinc selenide. Figure 3 Structural diagram at point A; Figure 5 This is a structural diagram of a graphite tower component of an apparatus for preparing large-size polycrystalline zinc selenide according to the present invention. Figure 6 This is a structural diagram of a graphite crucible lid for an apparatus for preparing large-size polycrystalline zinc selenide according to the present invention. Figure 7 This is a structural diagram of a deposition base for an apparatus for preparing large-size polycrystalline zinc selenide according to the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0021] This invention provides an apparatus and growth method for preparing large-size polycrystalline zinc selenide. By optimizing deposition process parameters and combining a multi-crucible continuous feeding mechanism, high-quality zinc selenide crystals with both diameter and thickness meeting the requirements are successfully prepared, satisfying the stringent requirements of downstream high-end devices for material size and thickness. Furthermore, by adopting a three-parallel dust collector structure and pulse solenoid valve purging technology, efficient collection and cleaning of byproduct zinc selenide dust are achieved, significantly reducing the system pressure rise rate and avoiding blockage and pressure fluctuations caused by dust accumulation, thus providing a continuous and stable low-pressure environment for crystal growth.

[0022] Figure 1-7 The diagram shown is a structural schematic of one embodiment of the apparatus for preparing large-size polycrystalline zinc selenide according to the present invention. Please refer to [link / reference]. Figures 1-7 An apparatus for preparing large-size polycrystalline zinc selenide according to this embodiment includes a chemical vapor deposition furnace assembly 100, a graphite tower assembly 200, and a dust collection system 300.

[0023] The chemical vapor deposition furnace assembly 100 includes a water-cooled furnace body 110, a lower furnace cover 120 installed at the bottom of the water-cooled furnace body 110, and an upper furnace cover 130 installed at the top of the water-cooled furnace body 110. An inlet pipe 140 extends through the bottom of the lower furnace cover 120. A graphite deposition chamber 150 is installed inside the water-cooled furnace body 110. The top end of the inlet pipe 140 extends into the water-cooled furnace body 110 and connects to the graphite deposition chamber 150. A guide pipe 150b is installed at the top of the graphite deposition chamber 150. The other end of 0b extends out of the side wall of the chemical vapor deposition furnace assembly 100 and is equipped with a gas outlet 150b-1. The water-cooled furnace body 110, lower furnace cover 120, and upper furnace cover 130 provide an environment for zinc selenide crystal growth. The inner wall of the water-cooled furnace body 110 is provided with a furnace body insulation cylinder 110a. The top of the lower furnace cover 120 is provided with a lower furnace cover insulation layer 120a, and the bottom of the upper furnace cover 130 is provided with an upper furnace cover insulation layer 130a. The furnace body insulation cylinder 110a, the lower furnace cover insulation layer 120a, and the upper furnace cover insulation layer... The heat exchange layer 130a is connected as a whole. The guide pipe 150b extends out of the side wall of the water-cooled furnace body 110 and is wrapped with an outlet insulation layer 150b-2 for furnace body insulation. The water-cooled furnace body 110 is equipped with a furnace body insulation cylinder 110a. The lower heater 120b is installed on the top of the lower furnace cover 120. The upper thermocouple 110c is installed on the side wall of the water-cooled furnace body 110 at the corresponding position of the graphite deposition chamber 150. The lower thermocouple is installed on the side wall of the water-cooled furnace body 110 at the corresponding position of the graphite tower assembly 200. 120c, a first vacuum gauge 130b is installed on the top of the upper furnace cover 130. The upper heater 110b provides the temperature required for zinc selenide crystal growth, and the lower heater 120b provides the temperature required for the melting, vaporization, and evaporation of zinc. The inlet pipe 140 serves as the inlet channel for hydrogen selenide and argon gas to the graphite deposition chamber. The first vacuum gauge 130b is used to display the furnace pressure. The upper thermocouple 110c is used to control the temperature of the upper heater 110b, and the lower thermocouple 120c is used to control the temperature of the lower thermocouple 120c. The graphite tower assembly 200 includes a graphite cover plate 210 located inside the water-cooled furnace body 110 and below the graphite deposition chamber 150, two graphite crucibles 220 symmetrically installed at the bottom of the graphite cover plate 210, and a graphite deposition chamber base 230 installed on top of the graphite cover plate 210. The bottom of the graphite deposition chamber 150 is connected to the top of the graphite deposition chamber base 230. Two inlet pipe through holes 210b are symmetrically opened on the top of the graphite cover plate 210, communicating with an inlet pipe 140. Two sets of first zinc vapor outlets 210a are symmetrically opened on the top of the graphite cover plate 210 with the inlet pipe through holes 210b as the center. Each set of first zinc vapor outlets 210a has three outlets and communicates with the graphite crucibles 220 below. The graphite deposition chamber base 230... The bottom of the graphite deposition chamber 230 has a confluence channel 230a. Two grooves 230b are symmetrically formed at the bottom of the graphite deposition chamber 230, centered on the confluence channel 230a. Each groove 230b is located above and connected to the first zinc vapor outlet 210a of each group. Three zinc vapor channels 230b-1 are formed on the sidewalls of the grooves 230b, and these channels are connected to the confluence channel 230a. A second zinc vapor outlet 230a-1 is formed at the top of the confluence channel 230a. A sealing gasket is installed inside the confluence channel 230a, and an inlet pipe outlet 230a-2 is formed at the bottom of the sealing gasket. The inlet pipe outlet 230a-2 is connected to the inlet pipe through hole 210b. The graphite crucible 220 is used to hold the zinc material. The container, with a circular graphite cover plate 210, allows zinc vapor from the graphite crucible 220 to reach the interior of the groove 230b through the first zinc vapor outlet 210a. The graphite deposition chamber base 230 serves as a ventilation channel for the zinc raw material. A groove 230b is located on each of the left and right sides of the back of the graphite deposition chamber base 230, with a confluence channel 230a in the middle. Each of the two side grooves 230b is connected to the confluence channel 230a through three built-in zinc vapor channels 230b-1, and these six channels are symmetrically distributed. The graphite deposition chamber base 230 contains three second zinc vapor outlets 230a-1 and two inlet pipe outlets 230a-2. The three second zinc vapor outlets 230a-1 and the two inlet pipe outlets 230a-2 are aligned in a straight line. The three zinc vapor channels 230b-1, three second zinc vapor outlets 230a-1, and two inlet pipe outlets 230a-2 on both sides are distributed parallel in the longitudinal direction and perpendicular in the transverse direction. Zinc vapor from the graphite crucible 220 first passes through the three first zinc vapor outlets 210a on the top of the graphite cover plate 210 to reach the groove 230b on one side of the back of the graphite deposition chamber base 230. Then, it reaches the inside of the confluence channel 230b-1 through the zinc vapor channel 230b-1. After the zinc vapor from the two graphite crucibles 220 converges inside the confluence channel 230a, it finally reaches the inside of the graphite deposition chamber 150 through the second zinc vapor outlet 230a-1. The graphite deposition chamber 150 is the chamber for the reaction of zinc vapor and hydrogen selenide gas to synthesize zinc selenide crystals.It consists of four identical graphite plates fixed together with graphite bolts, serving as the substrate for zinc selenide crystal growth. The internal dimensions of the graphite deposition chamber 150 are: length 500-1000mm, width 500-1000mm, and height 2000mm. Inside the graphite deposition chamber 150, there is a graphite guide pipe 150a for gas diversion, and a guide pipe 150b for gas guidance. The gas outlet 150b-1 is funnel-shaped to guide gas flow and prevent blockage.

[0024] The dust collection system 300 includes a main dust collector 310 connected to an outlet 150b-1, a parallel dust collection system 320 connected to the tail end of the main dust collector 310, and an exhaust system 330 connected to the tail end of the parallel dust collection system 320. A first dust collection bin 310a is installed at the bottom of the main dust collector 310. The exhaust system 330 includes a main dust collection pipe 330a, a pressure regulating valve 330b installed on the main dust collection pipe 330a, and a vacuum pump 330c installed on the main dust collection pipe 330a and located at the tail end of the pressure regulating valve 330b. The parallel dust collection system 320 includes three parallel dust collectors 320a and is connected to each of the main dust collectors 310 and the exhaust system 320. The parallel dust collector 320a has three dust collection branch pipes 320b at both ends. The front ends of each of the three dust collection branch pipes 320b are connected to the main dust collector 310, and the rear ends of each of the three dust collection branch pipes 320b are connected to the main dust collection pipe 330a. A second dust collection bin 320a-1 is installed at the bottom of the parallel dust collector 320a, and a pulse solenoid valve 320a-2 is installed at the top of the parallel dust collector 320a. A first pneumatic valve 320b-1 and a second vacuum gauge 320b-3 are installed on the body of the dust collection branch pipe 320b located at the front end of the parallel dust collector 320a. A second vacuum gauge 320b-3 is installed on the body of the dust collection branch pipe 320b located at the rear end of the parallel dust collector 320a. Two pneumatic valves 320b-2 and a third vacuum gauge 320b-4 are installed. The main dust collection pipe 330a is located at the front end of the pressure regulating valve 330b, and a leveling main pipe 330d is installed thereon. Three leveling branch pipes 330d-1 extend from the other end of the leveling main pipe 330d, and each of the three leveling branch pipes 330d-1 is connected to one of the three parallel dust collectors 320a. A third pneumatic valve 330d-2 is installed on the body of each leveling branch pipe 330d-1. The main dust collector 310 consists of a conical horn and a cylindrical body, with the first dust collection bin 310a below, collecting zinc selenide powder falling from the main body. [The following describes the working principle of the dust collection system.] The main filter primarily collects large-particle zinc selenide powder from the exhaust gas of the graphite tower. Small-particle zinc selenide powder is collected by three parallel dust collectors. The three parallel dust collectors operate in a one-in-two-out-of-service mode, meaning that when one is in use, the other two are in standby mode. The three parallel filters are used alternately according to a set program. The ratio of the dust collection main pipe diameter to the pressure regulating main pipe diameter is 20 to 80 mm. The pulse solenoid valve purging pressure of the parallel dust collectors is 1 to 10 kg / cm². The pressure rise rate of the dust collection system is less than 20 to 500 Pa / h, and the pressure rise rate of the furnace body is less than 20 to 300 Pa / h.

[0025] Using high-purity hydrogen selenide, high-purity zinc, and high-purity argon as carrier gases, the deposition process was carried out under the following conditions: vacuum P = 5000–12000 Pa, crucible temperature 660–780 °C, heating rate 0.25–2 °C / min, deposition temperature 720–810 °C, heating rate 0.2–1.5 °C / min, argon flow rate carrying zinc vapor in the crucible to zinc evaporation rate ratio 10–25 (Ar:Zn = 10–25), argon flow rate mixed with hydrogen selenide to hydrogen selenide flow rate ratio 10–30 (Ar:H₂Se = 10–50), and the molar ratio of hydrogen selenide to zinc during zinc selenide deposition 0.75–1.6 (H₂Se:Zn = 0.75–1.6). The zinc selenide growth rate was 70–210 μm / h. The furnace pressure rise rate is less than 100 Pa / h. Deposition ends when the zinc material in one crucible has evaporated completely, and the hydrogen selenide gas supply is stopped. The crucible cooling rate is 0.15–3 °C / min, and the deposition chamber cooling rate is 0.1–2 °C / min. This method can yield high-quality zinc selenide crystals with a thickness of 50–120 mm and a diameter of 100–300 mm.

[0026] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An apparatus for preparing large-size polycrystalline zinc selenide, characterized in that, include: A chemical vapor deposition furnace assembly (100) includes a water-cooled furnace body (110), a lower furnace cover (120) installed at the bottom of the water-cooled furnace body (110), and an upper furnace cover (130) installed at the top of the water-cooled furnace body (110). An air inlet pipe (140) extends through the bottom of the lower furnace cover (120). A graphite deposition chamber (150) is installed inside the water-cooled furnace body (110). The top end of the air inlet pipe (140) extends into the water-cooled furnace body (110) and is connected to the graphite deposition chamber (150). A guide pipe (150b) is installed at the top of the graphite deposition chamber (150). The other end of the guide pipe (150b) extends out of the side wall of the chemical vapor deposition furnace assembly (100) and is equipped with an air outlet (150b-1). The graphite tower assembly (200) includes a graphite cover plate (210) located inside the water-cooled furnace body (110) and below the graphite deposition chamber (150), two graphite crucibles (220) symmetrically installed at the bottom of the graphite cover plate (210), and a graphite deposition chamber base (230) installed on the top of the graphite cover plate (210), with the bottom of the graphite deposition chamber (150) connected to the top of the graphite deposition chamber base (230); The dust collection system (300) includes a main dust collector (310) connected to the outlet (150b-1), a parallel dust collection system (320) connected to the tail end of the main dust collector (310), and an exhaust system (330) connected to the tail end of the parallel dust collection system (320).

2. The apparatus for preparing large-size polycrystalline zinc selenide according to claim 1, characterized in that, The inner wall of the water-cooled furnace body (110) is provided with a furnace body insulation cylinder (110a), the top of the lower furnace cover (120) is provided with a lower furnace cover insulation layer (120a), the bottom of the upper furnace cover (130) is provided with an upper furnace cover insulation layer (130a), the furnace body insulation cylinder (110a), the lower furnace cover insulation layer (120a) and the upper furnace cover insulation layer (130a) are connected as a whole, and the guide pipe (150b) extends out of the side wall of the water-cooled furnace body (110) and is wrapped with an outlet insulation layer (150b-2).

3. The apparatus for preparing large-size polycrystalline zinc selenide according to claim 1, characterized in that, The water-cooled furnace body (110) is equipped with a furnace body insulation cylinder (110a) inside. The lower furnace cover (120) is equipped with a lower heater (120b) on the top. The water-cooled furnace body (110) is equipped with an upper thermocouple (110c) at a position corresponding to the graphite deposition chamber (150) on the side wall. The water-cooled furnace body (110) is equipped with a lower thermocouple (120c) at a position corresponding to the graphite tower assembly (200) on the side wall. The upper furnace cover (130) is equipped with a first vacuum gauge (130b) on the top.

4. The apparatus for preparing large-size polycrystalline zinc selenide according to claim 1, characterized in that, The graphite cover plate (210) has two symmetrically arranged air inlet pipe through holes (210b) on its top. The air inlet pipe through holes (210b) are connected to the air inlet pipe (140). The graphite cover plate (210) has two sets of first zinc vapor outlets (210a) symmetrically arranged on its top with the air inlet pipe through holes (210b) as the center. Each set of first zinc vapor outlets (210a) has three outlets and is connected to the graphite crucible (220) below.

5. The apparatus for preparing large-size polycrystalline zinc selenide according to claim 4, characterized in that, The bottom of the graphite deposition chamber base (230) is provided with a confluence groove (230a). The bottom of the graphite deposition chamber base (230) is symmetrically provided with two grooves (230b) with the confluence groove (230a) as the center. Each groove (230b) is located above the corresponding first zinc vapor outlet (210a) and communicates with the first zinc vapor outlet (210a). The side wall of the groove (230b) is provided with three zinc vapor channels (230b-1). The zinc vapor channels (230b-1) are communicated with the confluence groove (230a). The top of the confluence groove (230a) is provided with a second zinc vapor outlet (230a-1). A sealing gasket is installed inside the confluence groove (230a). The bottom end of the sealing gasket is provided with an air inlet pipe outlet (230a-2). The air inlet pipe outlet (230a-2) is communicated with the air inlet pipe through hole (210b).

6. The apparatus for preparing large-size polycrystalline zinc selenide according to claim 1, characterized in that, The main dust collector (310) is equipped with a first dust collection bin (310a) at the bottom. The exhaust system (330) includes a dust collection main pipe (330a), a pressure regulating valve (330b) installed on the body of the dust collection main pipe (330a), and a vacuum pump (330c) installed on the body of the dust collection main pipe (330a) and located at the tail of the pressure regulating valve (330b).

7. The apparatus for preparing large-size polycrystalline zinc selenide according to claim 1, characterized in that, The parallel dust collection system (320) includes three parallel dust collectors (320a) and dust collection branch pipes (320b) connected to both ends of each parallel dust collector (320a). The front ends of the three dust collection branch pipes (320b) are all connected to the main dust collector (310), and the rear ends of the three dust collection branch pipes (320b) are all connected to the main dust collection pipe (330a). A second dust collection bin (320a-1) is installed at the bottom of each parallel dust collector (320a). The parallel dust collector (320a) is equipped with a pulse solenoid valve (320a-2) on top. The dust collection branch pipe (320b) located at the front end of the parallel dust collector (320a) is equipped with a first pneumatic valve (320b-1) and a second vacuum gauge (320b-3). The dust collection branch pipe (320b) located at the rear end of the parallel dust collector (320a) is equipped with a second pneumatic valve (320b-2) and a third vacuum gauge (320b-4).

8. The apparatus for preparing large-size polycrystalline zinc selenide according to claim 1, characterized in that, The main dust collection pipe (330a) is equipped with a pressure equalization main pipe (330d) at the front end of the pressure regulating valve (330b). Three pressure equalization branch pipes (330d-1) extend from the other end of the main pressure equalization main pipe (330d). The three pressure equalization branch pipes (330d-1) are respectively connected to the three parallel dust collectors (320a). A third pneumatic valve (330d-2) is installed on the body of each pressure equalization branch pipe (330d-1).

9. A method for growing large-size polycrystalline zinc selenide, implemented by the apparatus for preparing large-size polycrystalline zinc selenide according to claims 1-8, characterized in that, The steps are as follows: S1. First, complete the program setting of the dust collection system (300). When the inlet pipe (140) of the dust collection system (300) starts to introduce hydrogen selenide gas, the flat pressure branch pipe (330d-1) corresponding to the uppermost parallel dust collector (320a), the first pneumatic valve (320b-1), the second pneumatic valve (320b-2), and the flat pressure branch pipe (330d-1) corresponding to the middle parallel dust collector (320a), and the first pneumatic valve (320b-2) corresponding to the lower parallel dust collector (320a) are all set up. When the first pneumatic valve (320b-1), the second pneumatic valve (320b-2), and the flat pressure branch pipe (330d-1) are simultaneously closed, the parallel dust collector (320a) located at the top is in use, while the parallel dust collectors (320a) located in the middle and bottom are in standby mode. The parallel dust collectors are switched in sequence according to the following conditions: when the pressure difference between the first pneumatic valve (320b-1) and the second pneumatic valve (320b-2) located in the middle is greater than 0 Pa for the chemical vapor deposition furnace assembly (100) ~ chemical vapor deposition furnace assembly (100), the parallel dust collectors located at the top are in use. The second pneumatic valve (320b-2) in the middle automatically opens. After waiting 10-60 seconds, the first pneumatic valve (320b-1) in the middle automatically opens. After waiting 10-60 seconds, the first pneumatic valve (320b-1) at the top automatically closes. After waiting 10-60 seconds, the second pneumatic valve (320b-2) at the top automatically closes, completing the switch from the upper parallel dust collector (320a) to the middle parallel dust collector (320a). Similarly, when the pressure difference of the middle parallel dust collector (320a) is greater than the chemical... When the pressure difference between the chemical vapor deposition furnace assembly (100) and the chemical vapor deposition furnace assembly (100) is 0 Pa, the parallel dust collector (320a) in the middle is switched to the parallel dust collector (320a) below. When the pressure difference between the parallel dust collector (320a) below is greater than 0 Pa, the parallel dust collector (320a) below is switched to the parallel dust collector (320a) above. The three parallel dust collectors (320a) are used in a cyclical manner in a top-to-bottom order. S2. After the parallel dust collector (320a) is used, zinc selenide powder adheres to the surface of the filter bag inside the parallel dust collector (320a). It is necessary to blow the powder on the filter bag into the second dust collection bucket (320a-1). Select the parallel dust collector (320a) to be blown, click the corresponding pulse solenoid valve (320a-2) to open, and blow according to the following program settings: click the pulse solenoid valve (320a-2) to open, and automatically close after 10 to 60 seconds of blowing time. After waiting for the zinc selenide powder to stand for 5 to 30 minutes, the corresponding second pneumatic valve (320b-2) will automatically open. When the pressure of the corresponding second vacuum gauge (320b-3) is equal to the pressure of the furnace body, the corresponding second pneumatic valve (320b-2) will automatically close, and the blowing is completed. S3. Install high-purity zinc ingots in two graphite crucibles (220), install graphite towers, gas inlet pipes, and furnaces, connect the furnace body to the gas path system, and evacuate the chemical vapor deposition furnace to the ultimate vacuum. When evacuating the furnace body to the ultimate vacuum, introduce 20-80 L / min of high-purity argon gas into the furnace through the gas path pipe for 30-300 min to complete the cleaning of the gas path and furnace body. At room temperature, introduce high-purity argon gas carrying zinc vapor into the crucibles, and introduce argon gas mixed with high-purity hydrogen selenide into the graphite deposition chamber (150) to maintain the furnace body vacuum degree of 5000-5000. The furnace cover (120) is 00Pa, and the furnace body is ventilated. The upper heater (110b) and the lower heater (120b) heat up simultaneously. The heating rate of the lower heater (120b) is 0.25~2℃ / min, and the temperature is raised to the zinc evaporation temperature of 660~780℃. The heating rate of the upper heater (110b) is 0.2~1.5℃ / min, and the temperature is raised to 720~810℃. The lower heater (120b) and the upper heater (110b) reach the zinc evaporation temperature and the deposition temperature, and wait for the zinc material to vaporize and evaporate, thus completing the furnace body heating. S4. After the upper heater (110b) and the lower heater (120b) are heated to the target temperature and kept constant, the zinc evaporation rate of the graphite crucible (220) stabilizes. The gas inlet pipe (140) uses high-purity hydrogen selenide gas to regulate the flow rate of high-purity argon gas carrying zinc vapor, the flow rate of argon gas mixed with high-purity hydrogen selenide, and the flow rate of high-purity hydrogen selenide, thereby controlling the ratio of hydrogen selenide to zinc vapor reaction and performing chemical vapor deposition crystal growth. When one of the graphite crucibles (220b) reaches the target temperature, the evaporation rate of zinc vapor in the graphite crucible (220b) stabilizes. 0) After the zinc material inside has evaporated, the hydrogen selenide gas is stopped. The upper heater (110b) and the lower heater (120b) are cooled down at the same time. The cooling rate of the lower heater (120b) is 0.15~3℃ / min, and the cooling rate of the upper heater (110b) is 0.1~2℃ / min. The furnace is opened to obtain high-quality zinc selenide crystals with a thickness of 50~lower furnace cover (120) mm and a diameter of chemical vapor deposition furnace assembly (100)~dust collection system (300) mm.

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