A system and method for synthesizing indium phosphide polycrystals

Abstract

A system and method for synthesizing indium phosphide polycrystals, relating to the technical field of polycrystal synthesis, including a high-pressure cavity, a heating body and a quartz tube, wherein the quartz tube and the heating body are both located in the high-pressure cavity, the heating body is located outside the quartz tube, the heating body has a high-temperature zone and a low-temperature zone, a quartz boat for holding red phosphorus is placed at one end of the quartz tube, a quartz boat for holding indium is placed at the other end of the quartz tube, the internal volume of the high-pressure cavity except the heating body and the quartz tube is equal to the internal volume of the quartz tube, red phosphorus is placed in the high-pressure cavity, the amount of red phosphorus in the high-pressure cavity is the same as the amount of red phosphorus in the quartz tube, and the red phosphorus in the high-pressure cavity and the red phosphorus in the quartz tube are both located in the low-temperature zone of the heating body. The present invention greatly ensures that the conversion of the two forms of phosphorus, P2 and P4, inside and outside the quartz tube is highly consistent, thereby ensuring that the pressure difference inside and outside the quartz tube is maintained within a reasonable range, and ensuring that the quartz tube will not explode.

Description

Technical Field

[0001] The invention belongs to the technical field of polycrystal synthesis, and in particular relates to a system and method for synthesizing indium phosphide polycrystals. Background Art

[0002] Indium phosphide single crystal material belongs to the second generation of semiconductor materials, has a zinc blende crystal structure, and its melting point is 1070 degrees Celsius. Because of its many electrochemical properties, it is currently widely used in optical communications, millimeter wave devices, integrated circuits, space exploration, solar cells, etc. It has an objective market prospect.

[0003] The growth of InP single crystals is inseparable from the synthesis of polycrystals. Qualified polycrystalline materials are the basis for growing high-quality single crystal materials. Therefore, the preparation of polycrystalline materials is particularly important.

[0004] At present, there are many methods for synthesizing InP polycrystals, including solute diffusion synthesis technology (SSD), horizontal Bridgman method (HB), horizontal gradient solidification method (HGF) and in-situ direct synthesis method (including phosphorus injection method and phosphorus liquid sealing method, etc.). The main mechanism of SSD synthesis technology is diffusion. Because the diffusion coefficient of P in In melt is very small, the synthesis speed is too slow to meet the needs of industrial production, and it is basically no longer used. The horizontal Bridgman method (HB) and horizontal gradient solidification method (HGF) are widely used in industry. Both methods synthesize indium phosphide polycrystals in a sealed quartz tube. Since the decomposition pressure of indium phosphide at the melting point is 2.75MPa, in order to prevent the quartz tube from exploding, the pressure difference between the inside and outside of the quartz tube needs to be maintained at less than 1~2atm. The pressure inside the quartz tube is mainly caused by phosphorus sublimation. Therefore, during the synthesis process, it is particularly important to accurately control the pressure difference between the inside and outside of the quartz tube.

[0005] Chinese patent application CN106757360A realizes the control of the pressure inside and outside the quartz tube according to the corresponding relationship between the phosphorus vapor pressure P and the temperature T in the phosphorus saturated vapor pressure equation lgP=aT-1+blgT+CT+d. However, the actual operation is very difficult. The saturated vapor pressure equation of the substance, namely the Antoine equation, not only has a certain scope of use, but also in the actual process, the pressure inside the quartz tube is not only affected by the temperature but also depends on the volume of the quartz tube and the form of phosphorus. Gaseous phosphorus has two forms, P2 and P4. When the temperature is between 1173 and 1473K, 1 mol of P4 vapor dissociates to produce 2 mol of P2 vapor, which increases the pressure inside the quartz tube. The reaction of the mutual conversion of the two forms of P2 and P4 cannot be calculated and predicted by the saturated vapor pressure equation. There are still certain risks and limitations in balancing the pressure difference inside and outside the quartz tube according to the relationship between pressure and temperature in the phosphorus saturated vapor pressure equation. Summary of the invention

[0006] Since the internal pressure of the quartz tube is mainly caused by the sublimation of phosphorus, in order to effectively control the pressure difference between the inside and outside of the quartz tube, the present invention provides a system and method for synthesizing indium phosphide polycrystals. The present invention generates sublimation of phosphorus both inside and outside the quartz tube, and the temperature inside and outside the quartz tube is the same, that is, the reaction conditions of the two forms of P2 and P4 sublimated inside and outside the quartz tube are basically the same, so the changes in the internal and external pressures of the quartz tube are basically the same, and the risk of the quartz tube exploding is greatly reduced.

[0007] The technical solution provided by the present invention is:

[0008] A method for synthesizing indium phosphide polycrystals comprises an indium phosphide polycrystal synthesis system, wherein the indium phosphide polycrystal synthesis system comprises a high-pressure cavity, a heating body and a quartz tube, wherein the quartz tube and the heating body are both located in the high-pressure cavity, the heating body is located outside the quartz tube, the heating body has a high-temperature zone and a low-temperature zone, a quartz boat for containing red phosphorus is placed at one end of the quartz tube, a quartz boat for containing indium is placed at the other end of the quartz tube, the inner volume of the high-pressure cavity excluding the heating body and the quartz tube is equal to the inner volume of the quartz tube, red phosphorus is placed in the high-pressure cavity, the amount of red phosphorus in the high-pressure cavity is the same as that in the quartz tube, the red phosphorus in the high-pressure cavity and the red phosphorus in the quartz tube are both located in the low-temperature zone of the heating body, the high-pressure cavity is connected to an air outlet pipeline, and a valve for adjusting the air outlet volume is arranged on the air outlet pipeline; the quartz tube is open at one end and closed at the other end, and the open end of the quartz tube is provided with a quartz cap, After the quartz tube is evacuated, the quartz cap is welded to the quartz tube wall; a cavity cap is provided at the end of the high-pressure cavity, and the cavity cap and the high-pressure cavity are detachably connected, which is convenient for taking and placing the quartz tube; an air guide device is provided in the middle of the inner side of the quartz tube, and the air guide device includes a quartz spacer cap and an air guide tube fixedly connected to the spacer cap, the spacer cap is tightly matched with the inner wall of the quartz tube, and one end of the air guide tube extends into the quartz boat containing indium; thereby increasing the contact between phosphorus and indium and accelerating the reaction speed; a cooling device is provided on the outer side of the high-pressure cavity, and after the reaction is completed, the cooling device is used to slowly cool the high-pressure cavity and the quartz tube; a support ring is provided in the middle of the quartz tube, the support ring is tightly matched with the inner wall of the quartz tube, and a vent hole is provided in the center of the support ring, and the support ring plays a role in supporting the middle of the quartz tube to prevent the quartz tube from being too long and breaking during the vacuuming process.

[0009] The method for synthesizing indium phosphide polycrystal comprises the following steps:

[0010] The first step is to load high-purity indium and high-purity red phosphorus into their own quartz boats, and place the two quartz boats at the two ends of the same quartz tube, and place them in an open position with quartz caps. Then, the inside of the quartz tube is vacuum treated in a vacuum furnace. When the vacuum degree requirement is reached, the quartz tube and the quartz cap are welded together with a hydrogen-oxygen flame. In this way, the inside of the entire quartz tube, that is, the synthesis space, is in a vacuum state, avoiding the volatilization of red phosphorus and the invasion of other impurities, so that the synthesized polycrystalline material has a higher purity. The second step is to put the treated vacuum quartz tube into the heating body, the heating body into the high-pressure cavity, adjust the position of the heating body in the high-pressure cavity, adjust the position of the quartz tube in the heating body, so that the quartz tube, the heating body and the high-pressure cavity are coaxially placed. After completion, close the high-pressure cavity and evacuate the high-pressure cavity.

[0011] Step 3: The heating body heats the quartz tube, so that the phosphorus vapor enters the indium melt to react and generate indium phosphide; at the same time, the phosphorus in the high-pressure cavity is gasified, so that the high-pressure cavity outside the quartz tube also has a certain gas pressure. Since the heating temperature of the phosphorus inside and outside the quartz tube is the same, the volume inside and outside the quartz tube is also the same, so the conversion of the two forms of phosphorus P2 and P4 is highly consistent, so that the pressure difference inside and outside the quartz tube is small; as the phosphorus in the quartz tube reacts with indium, the amount of phosphorus decreases; accordingly, the phosphorus vapor in the high-pressure cavity is released through the gas outlet pipeline, so as to ensure that the amount of gaseous phosphorus inside and outside the quartz tube is always maintained in a relatively balanced state, and to ensure that the pressure difference inside and outside the quartz tube is maintained within a reasonable range.

[0012] Step 4: After the reaction between phosphorus and indium is completed, turn off the heating element, and after the temperature of the high-pressure chamber and the quartz tube drops to room temperature, open the high-pressure chamber and take out the quartz tube.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] 1. In the present invention, the content volume of the high-pressure cavity except the heating body and the quartz tube is equal to the content volume of the quartz tube, red phosphorus is placed in the high-pressure cavity, the amount of red phosphorus in the high-pressure cavity is the same as the amount of red phosphorus in the quartz tube, the red phosphorus in the high-pressure cavity and the red phosphorus in the quartz tube are both located in the low-temperature zone of the heating body, and the high-pressure cavity is connected with an air outlet pipeline, and a valve for adjusting the air outlet volume is provided on the air outlet pipeline. Since the internal pressure of the quartz tube mainly comes from the sublimation of red phosphorus, the present invention has achieved the three characteristics of the same amount of red phosphorus inside and outside the quartz tube, the same volume inside and outside the quartz tube, and the same temperature of red phosphorus inside and outside the quartz tube, thereby greatly ensuring that the conversion of the two forms of P2 and P4 of phosphorus inside and outside the quartz tube is highly consistent, thereby ensuring that the pressure difference inside and outside the quartz tube is maintained within a reasonable range, and ensuring that the quartz tube will not explode. The present invention releases the red phosphorus in the high-pressure cavity through the air outlet pipeline, and the release rate is basically consistent with the reaction speed of phosphorus in the quartz tube, thereby still ensuring that the pressure difference inside and outside the quartz tube is controlled within a reasonable range.

[0015] 2. In the present invention, the support ring plays a role in supporting the middle of the quartz tube, thereby preventing the quartz tube from being too long and breaking during the vacuuming process.

[0016] 3. In the present invention, the spacer cap plays the same role as the support ring on the one hand, and on the other hand allows all the generated phosphorus vapor to pass through the indium solution, thereby increasing the reaction rate of the two and reducing the Si pollution caused by the long reaction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention.

[0018] Figure 2 It is a structural schematic diagram of the present invention when a support ring is arranged in the middle of the quartz tube.

[0019] Figure 3 It is a structural schematic diagram of the present invention when a gas guide device is arranged in the middle of the quartz tube.

[0020] In the figure: 1. high-pressure cavity; 2. heating body; 3. quartz cap; 4. cavity cap; 5. quartz tube; 6. air outlet pipeline; 7. control valve 1; 8. control valve 2; 9. support ring; 10. spacer cap; 11. air guide tube. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example

[0022] like Figure 1 As shown, this embodiment is a system for synthesizing indium phosphide polycrystals, including a high-pressure chamber 1, a heating body 2 and a quartz tube 5. The quartz tube 5 and the heating body 2 are both located in the high-pressure chamber 1, and the heating body 2 is located on the outside of the quartz tube 5. The heating body 2 has a high-temperature zone and a low-temperature zone. A quartz boat for holding red phosphorus is placed at one end of the quartz tube 5, and a quartz boat for holding indium is placed at the other end of the quartz tube 5. The above is a technology that already exists in the prior art and will not be repeated here.

[0023] The innovation of this embodiment is that: the internal volume of the high-pressure cavity 1 except the heating body 2 and the quartz tube 5 is equal to the internal volume of the quartz tube 5, red phosphorus is placed in the high-pressure cavity 1, the amount of red phosphorus in the high-pressure cavity 1 is the same as the amount of red phosphorus in the quartz tube 5, the red phosphorus in the high-pressure cavity 1 and the red phosphorus in the quartz tube 5 are both located in the low-temperature area of ​​the heating body 2, and the high-pressure cavity 1 is connected to the gas outlet pipeline 6, and the gas outlet pipeline 6 is provided with a valve for adjusting the gas outlet volume. Since the internal pressure of the quartz tube 5 mainly comes from the sublimation of red phosphorus, this embodiment has achieved the three characteristics of the same amount of red phosphorus inside and outside the quartz tube 5, the same volume inside and outside the quartz tube 5, and the same temperature of red phosphorus inside and outside the quartz tube 5, thereby greatly ensuring that the conversion of the two forms of phosphorus P2 and P4 inside and outside the quartz tube 5 is highly consistent, thereby ensuring that the pressure difference inside and outside the quartz tube 5 is maintained within a reasonable range, and ensuring that the quartz tube 5 will not explode.

[0024] The present invention releases the red phosphorus in the high-pressure cavity 1 through the gas outlet pipeline 6, and the release rate is basically consistent with the reaction rate of phosphorus in the quartz tube 5 (the release rate of red phosphorus needs to be obtained through repeated tests based on the specific size of the quartz tube and the amount of material released. After obtaining specific data, the conclusion obtained from the test can be used each time the indium phosphide polycrystalline material is synthesized), thereby still ensuring that the pressure difference between the inside and outside of the quartz tube 5 is controlled within a reasonable range. A control valve 7 is set on the gas outlet pipeline 6 to control the release rate of phosphorus.

[0025] The quartz tube 5 is open at one end and closed at the other end. The open end of the quartz tube 5 is provided with a quartz cap 3. After the quartz tube 5 is evacuated, the quartz cap 3 is welded to the wall of the quartz tube 5 to prevent the volatilization of red phosphorus and other impurities from invading the quartz tube 5, thereby making the synthesized polycrystalline material higher in purity.

[0026] A cavity cap 4 is disposed at the end of the high-pressure cavity 1 , and the cavity cap 4 and the high-pressure cavity 1 are detachably connected, so that the quartz tube 5 can be easily taken in and out.

[0027] A cooling device is provided outside the high-pressure cavity 1 . After the reaction is completed, the cooling device is used to slowly cool the high-pressure cavity 1 and the quartz tube 5 .

[0028] The synthesis method using the system for synthesizing indium phosphide polycrystals comprises the following steps:

[0029] The first step is to load high-purity indium and high-purity red phosphorus into their own quartz boats, and place the two quartz boats at the two ends of the same quartz tube 5, and place the quartz cap 3 in an open position, and then put the quartz tube 5 in a vacuum oven for vacuum treatment. When the vacuum requirement is reached, the quartz tube 5 and the quartz cap 3 are welded together with a hydrogen-oxygen flame, so that the entire quartz tube 5, that is, the synthesis space is in a vacuum state, to avoid the volatilization of red phosphorus and the invasion of other impurities, so that the synthesized polycrystalline material has a higher purity. The second step is to put the treated vacuum quartz tube 5 into the heating body 2, and the heating body 2 into the high-pressure cavity 1, and adjust the position of the heating body 2 in the high-pressure cavity 1, and adjust the position of the quartz tube 5 in the heating body 2, so that the quartz tube 5, the heating body 2 and the high-pressure cavity 1 are coaxially placed, and after completion, the high-pressure cavity 1 is closed and the high-pressure cavity 1 is evacuated. The specific steps of vacuuming are: connecting control valve 28 to the air outlet pipeline 6, connecting the other end of control valve 28 to the vacuum pump, turning on the vacuum pump and control valve 28 at the same time, vacuuming the high-pressure chamber 1, and after the vacuuming is completed, closing the vacuum pump and control valve 28 at the same time.

[0030] Step 3: The heating body 2 heats the quartz tube 5, so that the phosphorus vapor enters the indium melt to react and generate indium phosphide; at the same time, the phosphorus in the high-pressure cavity 1 is gasified, so that the high-pressure cavity 1 outside the quartz tube 5 also has a certain gas pressure. Since the heating temperature of the phosphorus inside and outside the quartz tube 5 is the same, the volume inside and outside the quartz tube 5 is also the same, so the conversion of the two forms of phosphorus P2 and P4 is highly consistent, so that the pressure difference inside and outside the quartz tube 5 is small; as the phosphorus in the quartz tube 5 reacts with indium, the amount of phosphorus decreases; correspondingly, the phosphorus vapor in the high-pressure cavity 1 is released through the gas outlet pipeline 6, so as to ensure that the amount of gaseous phosphorus inside and outside the quartz tube 5 is always maintained in a relatively balanced state, and to ensure that the pressure difference inside and outside the quartz tube 5 is maintained within a reasonable range.

[0031] Step 4: After the reaction between phosphorus and indium is completed, the heating body 2 is turned off, and after the temperature of the high-pressure chamber 1 and the quartz tube 5 drops to room temperature, the high-pressure chamber 1 is opened and the quartz tube 5 is taken out. Example

[0032] like Figure 2 As shown, this embodiment is designed on the basis of the first embodiment, and a support ring 9 is provided in the middle of the quartz tube 5, the support ring 9 is tightly matched with the inner wall of the quartz tube 5, and a vent hole is provided in the center of the support ring 9, and the support ring 9 plays a role in supporting the middle of the quartz tube 5 to prevent the quartz tube 5 from being too long and breaking during the vacuuming process. Example

[0033] like Figure 3As shown, this embodiment adds an air guide device on the basis of the first embodiment. The air guide device is arranged in the middle of the inner side of the quartz tube 5. The air guide device includes a quartz spacer cap 10 and an air guide tube 11 fixedly connected to the spacer cap 10. The spacer cap 10 is tightly matched with the inner wall of the quartz tube 5. One end of the air guide tube 11 extends into the quartz boat containing indium. Thereby increasing the contact between phosphorus and indium and accelerating the reaction speed. The spacer cap 10 also plays a role in supporting the middle of the quartz tube 5 to prevent the quartz tube 5 from being too long and breaking during the vacuuming process.

Claims

1. A method for synthesizing indium phosphide polycrystal, characterized in that: The invention comprises an indium phosphide polycrystal synthesis system, wherein the indium phosphide polycrystal synthesis system comprises a high-pressure chamber (1), a heating body (2) and a quartz tube (5), wherein the quartz tube (5) and the heating body (2) are both located in the high-pressure chamber (1), the heating body (2) is located outside the quartz tube (5), the heating body (2) has a high-temperature zone and a low-temperature zone, a quartz boat for containing red phosphorus is placed at one end of the quartz tube (5), and a quartz boat for containing indium is placed at the other end of the quartz tube (5), The internal volume of the high-pressure cavity (1) outside the heating body (2) and the quartz tube (5) is equal to the internal volume of the quartz tube (5); red phosphorus is placed in the high-pressure cavity (1); the amount of red phosphorus in the high-pressure cavity (1) is the same as the amount of red phosphorus in the quartz tube (5); the red phosphorus in the high-pressure cavity (1) and the red phosphorus in the quartz tube (5) are both located in the low-temperature area of ​​the heating body (2); the high-pressure cavity (1) is connected to an air outlet pipeline (6); and a valve for adjusting the air outlet volume is provided on the air outlet pipeline (6); The synthesis method of indium phosphide polycrystal comprises the following steps: The first step is to load high-purity indium and high-purity red phosphorus into respective quartz boats, and place the two quartz boats at the two ends of the same quartz tube (5), respectively, and place the quartz caps (3) at the open positions, and then place the quartz tube (5) in a vacuum oven for vacuum treatment. When the vacuum degree requirement is reached, the quartz tube (5) and the quartz caps (3) are welded together with a hydrogen-oxygen flame, so that the interior of the entire quartz tube (5), that is, the synthesis space, is in a vacuum state, thereby preventing the volatilization of red phosphorus and the intrusion of other impurities, and making the synthesized polycrystalline material higher in purity; In the second step, the processed vacuum quartz tube (5) is placed in the heating body (2), the heating body (2) is placed in the high-pressure chamber (1), the position of the heating body (2) in the high-pressure chamber (1) is adjusted, and the position of the quartz tube (5) in the heating body (2) is adjusted so that the quartz tube (5), the heating body (2) and the high-pressure chamber (1) are coaxially placed. After completion, the high-pressure chamber (1) is closed and the high-pressure chamber (1) is evacuated; Step 3: The heating body (2) heats the quartz tube (5) so that phosphorus vapor enters the indium melt to react and generate indium phosphide; at the same time, the phosphorus in the high-pressure chamber (1) is gasified, so that the high-pressure chamber (1) outside the quartz tube (5) also has a certain gas pressure. Since the phosphorus inside and outside the quartz tube (5) is heated at the same temperature, the volume inside and outside the quartz tube (5) is also the same, so the conversion of the two forms of phosphorus, P2 and P4, is highly consistent, so that the pressure difference inside and outside the quartz tube (5) is small; as the phosphorus in the quartz tube (5) reacts with indium, the amount of phosphorus decreases; accordingly, the phosphorus vapor in the high-pressure chamber (1) is released through the gas outlet pipeline (6), so as to ensure that the amount of gaseous phosphorus inside and outside the quartz tube (5) is always maintained in a relatively balanced state, and ensure that the pressure difference inside and outside the quartz tube (5) is maintained within a reasonable range; Step 4: After the reaction between phosphorus and indium is completed, the heating body (2) is turned off, and after the temperature of the high-pressure chamber (1) and the quartz tube (5) drops to room temperature, the high-pressure chamber (1) is opened and the quartz tube (5) is taken out.

2. The method for synthesizing indium phosphide polycrystal according to claim 1, characterized in that: The quartz tube (5) is open at one end and closed at the other end. The open end of the quartz tube (5) is provided with a quartz cap (3), and the quartz cap (3) is welded to the wall of the quartz tube (5).

3. The method for synthesizing indium phosphide polycrystal according to claim 1, characterized in that: A cavity cap (4) is provided at the end of the high-pressure cavity (1), and the cavity cap (4) and the high-pressure cavity (1) are detachably connected.

4. The method for synthesizing indium phosphide polycrystal according to claim 1, characterized in that: An air guide device is provided in the middle of the inner side of the quartz tube (5), the air guide device comprising a quartz spacer cap (10) and an air guide tube (11) fixedly connected to the spacer cap (10), the spacer cap (10) is tightly matched with the inner wall of the quartz tube (5), and one end of the air guide tube (11) extends into the quartz boat containing indium.

5. The method for synthesizing indium phosphide polycrystal according to claim 1, characterized in that: A cooling device is provided outside the high-pressure cavity (1). After the reaction is completed, the cooling device is used to slowly cool the high-pressure cavity (1) and the quartz tube (5).

6. The method for synthesizing indium phosphide polycrystal according to claim 1, characterized in that: A support ring (9) is provided in the middle of the quartz tube (5). The support ring (9) is tightly matched with the inner wall of the quartz tube (5), and a vent hole is provided in the center of the support ring (9).

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