One-step synthesis process of indium antimonide single crystals

Abstract

The present invention discloses a one-step process for synthesizing indium antimonide single crystals, belonging to the field of indium antimonide single crystal preparation. The process comprises the following steps: adding indium and antimony particles to a reactor, and arranging the reactor horizontally; introducing an inert protective gas, and controlling the reactor to rotate and heat the reactor to generate indium antimonide polycrystals; then flipping the reactor from horizontal to vertical, first heating the conical portion of the reactor so that the indium antimonide crystals at the conical portion are converted back into a low-viscosity polycrystalline melt and enter a capillary tube, where they form single crystals; then heating the cylindrical portion of the reactor, and controlling the heating area of ​​the cylindrical portion to gradually move upward, so that the heated lower polycrystalline melt recrystallizes and, under induction, forms indium antimonide single crystals with the same crystal orientation as the single crystal in the capillary tube. The present invention not only improves the synthesis efficiency of indium antimonide single crystals, but also uses only one reactor, greatly reducing environmental pollution and ensuring the purity and performance of the indium antimonide single crystals.

Description

Technical Field

[0001] The present invention relates to the field of preparation of indium antimonide single crystals, and in particular to a one-step process for synthesizing indium antimonide single crystals. Background Art

[0002] Indium antimonide single crystal is an important III-V compound semiconductor with the chemical formula InSb. The band gap of indium antimonide is only 0.17eV, corresponding to an excitation light wavelength of 5.3 microns, which is in the mid-to-far infrared region. It is an ultra-narrow bandgap direct bandgap semiconductor with an electron mobility of up to 78,000 cm 2 / V·s, almost 60 times that of silicon. In general, indium antimonide offers advantages such as an ultra-narrow bandgap, ultra-high electron mobility, high quantum efficiency, and fast response speed. These properties give indium antimonide unique advantages in the mid- and far-infrared, high-speed, and high-frequency fields. Indium antimonide substrates can be widely used in products such as infrared detectors, photomagnetic detectors, Hall devices, and magnetoresistive devices. Despite its distinct characteristics, indium antimonide crystals do not exist naturally in nature and must be synthesized artificially under specific conditions.

[0003] Conventional indium antimonide production processes typically begin with the synthesis of polycrystalline materials, which are then further grown into single crystals using the CZ method. However, this method has high equipment costs, high crystal stress, high dislocation density, and complex crystal growth processes, making it difficult to grow large, low-dislocation single crystals.

[0004] Chinese invention patent application number 202211446453.8 discloses an indium antimonide crystal and its preparation method. This method involves charging indium and antimony into a single crystal furnace at a molar ratio of In:Sb = 1.5-1.4:1. Maintaining a hydrogen atmosphere in the single crystal furnace, the indium and antimony are heated to 800-1000°C to melt for 12-36 hours. The temperature is then lowered to the crystal growth temperature and held until the crystal is fully grown, yielding an indium antimonide crystal. Chinese invention patent application number 202010540297.6 discloses a method and apparatus for preparing an indium antimonide single crystal. This method involves adding indium antimonide seed crystals, indium antimonide polycrystals, and boron trioxide to a sealed container with a separately temperature-controlled heating zone above. The crystal is then grown using the VB (Vertical Bridgman) method to produce the indium antimonide single crystal.

[0005] The above method has the following disadvantages: first, the charge has a large excess of indium, which will inevitably lead to excess indium after the reaction is completed. Finally, the indium needs to be removed separately, and the performance of the formed indium antimonide crystals will also be reduced due to the presence of a large amount of indium inclusions; second, it is necessary to first synthesize indium antimonide polycrystals and then further pull out indium antimonide single crystals, or use indium antimonide polycrystals as raw materials to further prepare indium antimonide single crystals, which has a long process flow and high equipment cost; third, due to the transfer or addition of substances during the preparation process, or the need to use multiple reactors, the possibility of crystal contamination increases, resulting in insufficient crystal purity. Summary of the Invention

[0006] Based on the above technical problems, the present invention proposes a one-step process for synthesizing indium antimonide single crystals.

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

[0008] A one-step process for synthesizing an indium antimonide single crystal employs a reactor comprising a cylindrical portion, an end cap disposed at one end of the cylindrical portion, and a tapered portion disposed at the other end of the cylindrical portion. The cylindrical portion and the tapered portion are both hollow and interconnected, and a capillary is connected at the end of the tapered portion. The process comprises the following steps:

[0009] S1. Add indium particles and antimony particles into a reactor, and arrange the reactor horizontally; introduce inert protective gas into the reactor, control the rotation of the reactor, and heat the reactor;

[0010] S2, first heating to 700-750°C to completely melt the indium and antimony particles into liquid form, and then keeping the temperature; then continuing to heat to 900-950°C, keeping the temperature to react and form indium antimonide polycrystals;

[0011] S3, stopping the rotation of the reactor and cooling it until there is no liquid in the reactor;

[0012] S4, turning the reactor 90 degrees from horizontal to vertical, with the capillary at the bottom; then heating the tapered portion of the reactor so that the indium antimonide crystals at the tapered portion are converted back into a low-viscosity polycrystalline melt;

[0013] S5. The low-viscosity polycrystalline melt enters the capillary tube under the action of gravity and capillary action, gradually lowering the temperature of the capillary tube and forming a single crystal in the capillary tube;

[0014] S6. The columnar portion of the reactor near the conical portion is heated so that the indium antimonide crystal at this position is transformed into a low-viscosity polycrystalline melt again. Then, the heating area of ​​the columnar portion is controlled to gradually move upward. During the gradual upward movement of the heating area, the lower polycrystalline melt is recrystallized and induced to form an indium antimonide single crystal with the same crystal orientation as the single crystal in the capillary.

[0015] Preferably, the center line of the cylindrical portion and the center line of the conical portion coincide with each other, and the capillary tubes are arranged along the extending direction of the center lines; the diameter of the capillary tubes is 1-1.5 mm and the length is 120-150 mm.

[0016] Preferably, in step S1 , the molar ratio of indium particles to antimony particles is 1:1.

[0017] Preferably, in step S1: the inert protective gas is argon; the rotation rate of the reactor is controlled to be 8-10 r / min; and the heating temperature rise rate is controlled to be 5-10° C. / min.

[0018] Preferably, in step S2: the temperature is controlled to be kept at 700-750°C for 4-5 hours; then the temperature is increased to 900-950°C at a rate of 25-30°C / min, and the reaction is carried out at this temperature for 4-5 hours; during the process of increasing the temperature to 900-950°C and keeping the temperature for reaction, the rotation rate of the reactor is increased to 15-20r / min.

[0019] Preferably, in step S3: the temperature is lowered to 450-500° C. and maintained for 0.5-1 hour.

[0020] Preferably, in step S4: the reactor is heated by an electromagnetic induction heating coil, which can move up and down along the center line of the reactor; the power of the electromagnetic induction heating coil is controlled to be 1200-1500W; the tapered portion of the reactor is heated to 700-750°C, and the heating rate is controlled to be 20-30°C / min.

[0021] Preferably, step S5 further includes a step of evacuating the capillary tube.

[0022] Preferably, in step S5: the temperature of the capillary is gradually reduced to 500±0.5°C at a rate of 0.5°C / min; while cooling, an external magnetic field with a strength of 0.2-0.5 Tesla is applied to the outside of the capillary; after 30-45 minutes, the temperature of the capillary is gradually reduced to 400±0.5°C at a rate of 0.5°C / min.

[0023] Preferably, in step S6: the electromagnetic induction heating coil is gradually moved upward at a speed of 1-1.2 cm / h; during the upward movement of the electromagnetic induction heating coil, the polycrystalline melt below the electromagnetic induction heating coil is controlled to condense at a speed of 3-5°C / min and recrystallize.

[0024] The beneficial technical effects of the present invention are:

[0025] The present invention utilizes a specially designed pressure-resistant reactor. The reactor is first placed horizontally, and indium and antimony are introduced in a 1:1 ratio. Under an inert atmosphere, the reactor is rotated to stir the reactants, ensuring thorough mixing of the indium and antimony before a chemical reaction occurs, producing uniform indium antimonide polycrystals. After the indium antimonide polycrystals have reacted completely, the reactor is converted from horizontal to vertical. At this point, an electromagnetic induction heating coil is energized to locally heat the reactor, allowing a portion of the melt to flow into a vacuum capillary tube, forming elongated single crystals of a specific crystal form. Subsequently, the growth rate is adjusted appropriately, and the indium antimonide polycrystals are converted into single crystals of the specific crystal form through gradient solidification using the electromagnetic induction heating coil. This method not only improves the efficiency of indium antimonide single crystal synthesis but also utilizes only a single reactor, significantly reducing environmental pollution and ensuring the purity and performance of the indium antimonide single crystals. The present invention also offers advantages such as a simple process flow, convenient operation, low device cost, and ease of implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a process flow chart for synthesizing indium antimonide single crystals using a one-step method according to the present invention;

[0027] Figure 2 This is a simplified structural diagram of the reactor used in the present invention;

[0028] Figure 3 This is a schematic diagram of the structural principle of an embodiment of the present invention in which the reactor is arranged horizontally to prepare indium antimonide polycrystals;

[0029] Figure 4 A schematic diagram of the structural principle of an embodiment of the present invention in which the reactor is converted into a vertical arrangement for preparing indium antimonide single crystals;

[0030] Figure 5 This is the EDS analysis spectrum of the indium antimonide single crystal prepared in Example 1 of the present invention;

[0031] Figure 6 This is the XRD scan pattern of the indium antimonide single crystal prepared in Example 1 of the present invention.

[0032] In the figure: 1- cylindrical part, 2- end cover, 3- conical part, 4- capillary, 5- heating furnace, 6- mechanical gripper, 7- magnetic induction heating coil. DETAILED DESCRIPTION

[0033] Existing technology simply uses a heating and melting method to first synthesize indium and antimony into polycrystalline indium antimonide, which is then pulled into single crystals via the Czochralski method. This method has a long reaction time and a slow reaction rate. Furthermore, due to the excessive addition of indium, an excess of indium can form. The resulting indium antimonide crystals suffer from poor performance due to the presence of a high amount of indium inclusions. Furthermore, traditional methods typically synthesize polycrystalline materials first, followed by further pulling into single crystals. This results in a lengthy process, requires multiple reaction equipment, and is prone to elemental contamination.

[0034] Taking into full consideration the existing technical problems, the present invention places a certain amount of high-purity antimony particles and high-purity indium particles in proportion into a pressure-resistant reactor. The bottom of the reactor is designed to be conical or funnel-shaped, and the bottom funnel gradually transitions to a closed needle-shaped capillary. Initially, the reactor is arranged horizontally, the raw materials are placed into the reactor, and high-purity argon gas is introduced into the reactor. After the argon gas completely replaces the air in the reactor, the mixture is slowly heated, and the reactor is controlled to rotate to ensure uniform mixing of the raw materials. As the temperature gradually increases, the indium and antimony particles gradually melt and react. After they are completely converted into polycrystalline indium antimonide, the rotation is stopped. The reactor is then slowly rotated to a vertical position, and an electromagnetic induction heating coil is used to first heat the conical portion, so that the needle-shaped capillary is filled with polycrystalline liquid. Then, the needle-shaped capillary region is strictly controlled to form a single crystal material with a certain crystal orientation in the capillary. Then, under the induction of the single crystal product in the capillary, a temperature gradient is controlled to form a large-scale single crystal material with the same crystal orientation as the capillary single crystal in the reactor.

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] A one-step process for synthesizing an indium antimonide single crystal employing a reactor such as Figure 2 As shown, the reactor includes a cylindrical portion 1, an end cap 2 is provided at one end of the cylindrical portion 1, and a conical portion 3 is provided at the other end of the cylindrical portion 1. The cylindrical portion 1 and the conical portion 3 are both hollow inside and connected to each other, and a capillary 4 is connected at the end of the conical portion 3.

[0038] like Figure 1 As shown, the process includes the following steps:

[0039] S1. Indium and antimony particles are added to a reactor in a molar ratio of 1:1 (corresponding to a mass ratio of 114.818:121.76). The reactor is arranged horizontally. High-purity argon (purity 5N or higher) is introduced into the reactor as an inert protective gas, and the system pressure is maintained at 1 atm. The reactor is rotated at a rate of 10 rpm. The reactor is heated at a heating rate of 10°C / min to ensure that the indium and antimony reactants are fully mixed and in contact with each other.

[0040] S2. First, heat the reactor to 750°C to completely melt the indium and antimony particles into a liquid state, and maintain this temperature for 4 hours. Increase the reactor's rotation rate to 20 rpm to ensure more thorough and uniform mixing of the indium and antimony reactants in the liquid state, and maintain this rotation rate for 0.5 hours. Then, increase the temperature to 900°C at a rate of 30°C / min and maintain the reaction for 5 hours to allow the indium and antimony to completely react and form indium antimonide polycrystals.

[0041] S3. Stop the rotation of the reactor and cool it down to 500° C., and maintain the temperature for more than 0.5 h until no liquid exists in the reaction system, which proves that indium and antimony have completely reacted to form indium antimonide polycrystals.

[0042] S4. Flip the reactor 90° from horizontal to vertical, with the capillary at the bottom. First, heat the conical portion of the reactor at a controlled heating rate of 30°C / min to 700°C, so that the indium antimonide crystals in the conical portion are converted back into a low-viscosity polycrystalline melt.

[0043] S5. Connect the end of the capillary to the negative pressure system and evacuate the interior. The low-viscosity polycrystalline melt enters the capillary under the action of pressure difference and capillary action. Gradually reduce the temperature of the capillary to 500±0.5℃ at a rate of 0.5℃ / min; while cooling, apply an external magnetic field with a strength of 0.5 Tesla to the outside of the capillary to ensure that the crystal orientation of the crystal is consistent. After 30 minutes, gradually reduce the temperature of the capillary to 400±0.5℃ at a rate of 0.5℃ / min to form a single crystal in the capillary. The cooling of the capillary can be achieved by using a temperature controller to control the system. The N and S poles of the above-mentioned external magnetic field are respectively applied to both sides of the capillary.

[0044] S6. The columnar portion of the reactor near the tapered portion is heated so that the indium antimonide crystals at this location are converted back into a low-viscosity polycrystalline melt. The heating area of ​​the columnar portion is then controlled to gradually move upward at a speed of 1 cm / h. During the gradual upward movement of the heating area, the lower polycrystalline melt is controlled to condense and recrystallize at a rate of 5°C / min, inducing the polycrystalline melt to form a high-purity indium antimonide single crystal with the same crystal orientation as the single crystal in the capillary. This condensation cooling method can also be achieved by using a temperature controller to control the temperature, or other conventional methods can also be used.

[0045] The indium antimonide single crystal obtained in this embodiment was subjected to EDS analysis, and the EDS analysis spectrum is as follows: Figure 5 As shown. Figure 5 It can be seen that the crystallization ratio of InSb crystals is almost 1:1, which is very reasonable. Figure 6 The XRD scan of the InSb single crystal obtained in the embodiment of the present invention is as follows: Figure 6 It can be seen that the (111) crystal orientation peak of the synthetic crystal is very obvious.

[0046] Example 2

[0047] The reactor is similar to Example 1, except that the reactor is designed more specifically as follows. The reactor is made of quartz, and the inner diameter of the cylindrical portion 1 of the reactor is 3.5 inches. The centerline of the cylindrical portion coincides with the centerline of the tapered portion, and the capillaries are arranged along the centerline. The capillaries have a diameter of 1-1.5 mm and a length of 120-150 mm. Specifically, the capillaries can be configured to have a diameter of 1 mm and a length of 120 mm.

[0048] When the reactor is arranged horizontally and used to prepare indium antimonide polycrystals, the reactor can be placed in a heating furnace 5 for heating. Figure 3 As shown, the reactor can be further clamped by a mechanical clamp 6, which is in transmission connection with a driving device, so that the driving device drives the reactor to rotate circumferentially through the mechanical clamp.

[0049] The reactor can be flipped 90 degrees from horizontal to vertical, which can be achieved by using conventional clamping devices.

[0050] When the reactor is converted to a vertical position and fixed, a magnetic induction heating coil 7 can be installed on the outside of the reactor, and the magnetic induction heating coil can be moved up and down along the center line of the reactor under the drive of an external device to heat a local position of the reactor as needed. The movement of the magnetic induction heating coil up and down along the reactor can be achieved in a variety of ways, such as connecting the magnetic induction heating coil to one end of a hanging rope, and winding the other end of the hanging rope on a wire drum. By controlling the winding and release of the hanging rope, the movement of the magnetic induction heating coil along the reactor can be achieved. Of course, several other methods can also be used to achieve this.

[0051] The power of the magnetic induction heating coil is set to 1200-1500W.

[0052] Example 3

[0053] The one-step process for synthesizing an indium antimonide single crystal comprises the following steps:

[0054] S1. Indium and antimony particles are added to a reactor in a molar ratio of 1:1 (corresponding to a mass ratio of 114.818:121.76). The reactor is arranged horizontally. High-purity argon (purity 5N or higher) is introduced into the reactor as an inert protective gas, and the system pressure is maintained at 1 atm. The reactor is rotated at a rate of 8 rpm. The reactor is heated at a heating rate of 5°C / min to ensure that the indium and antimony reactants are fully mixed and in contact with each other.

[0055] S2. First, heat the reactor to 700°C to completely melt the indium and antimony particles into a liquid state, and maintain this temperature for 5 hours. Then, increase the reactor's rotation speed to 15 rpm to ensure more thorough and uniform mixing of the indium and antimony reactants in the liquid state, and maintain this speed for 0.5 hours. Then, increase the temperature to 950°C at a rate of 25°C / min and maintain the reaction at this temperature for 4 hours to allow the indium and antimony to completely react and form indium antimonide polycrystals.

[0056] S3. Stop the rotation of the reactor and cool it down to 450°C, and maintain the temperature for more than 1 hour until no liquid exists in the reaction system, which proves that indium and antimony have completely reacted to form indium antimonide polycrystals.

[0057] S4. Flip the reactor 90° from horizontal to vertical, with the capillary at the bottom. Use a 1200W magnetic induction heating coil to heat the conical portion of the reactor at a controlled heating rate of 20°C / min to 750°C, causing the indium antimonide crystals in the conical portion to return to a low-viscosity polycrystalline melt.

[0058] S5. The low-viscosity polycrystalline melt enters a capillary tube under the influence of gravity and capillary action. The capillary temperature is gradually lowered at a rate of 0.5°C / min to 500±0.5°C. Simultaneously, a 0.2 Tesla external magnetic field is applied to the outside of the capillary tube to ensure uniform crystallization orientation. After 45 minutes, the capillary temperature is gradually lowered at a rate of 0.5°C / min to 400±0.5°C, forming a single crystal in the capillary tube.

[0059] S6. The columnar portion of the reactor near the tapered portion is heated to convert the indium antimonide crystals at that location back into a low-viscosity polycrystalline melt. The heated area of ​​the columnar portion is then gradually moved upward at a speed of 1.2 cm / h. During the upward movement of the heated area, the lower polycrystalline melt is condensed and recrystallized at a rate of 3°C / min, thereby inducing the polycrystalline melt to form a high-purity indium antimonide single crystal having the same crystal orientation as the single crystal in the capillary.

[0060] Parts not described in the above methods can be achieved by adopting or drawing on existing technologies.

[0061] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A one-step process for synthesizing indium antimonide single crystals, characterized in that: A reactor is used, which includes a cylindrical portion, an end cap is provided at one end of the cylindrical portion, and a tapered portion is provided at the other end of the cylindrical portion. The cylindrical portion and the tapered portion are both hollow and interconnected, and the end of the tapered portion is connected to a capillary. The process includes the following steps: S1. Add indium particles and antimony particles into a reactor, and arrange the reactor horizontally; introduce inert protective gas into the reactor, control the rotation of the reactor, and heat the reactor; S2, first heating to 700-750°C to completely melt the indium and antimony particles into liquid form, and then keeping the temperature; then continuing to heat to 900-950°C, keeping the temperature to react and form indium antimonide polycrystals; S3, stopping the rotation of the reactor and cooling it until there is no liquid in the reactor; S4, turning the reactor 90 degrees from horizontal to vertical, with the capillary at the bottom; then heating the tapered portion of the reactor so that the indium antimonide crystals at the tapered portion are converted back into a low-viscosity polycrystalline melt; S5, low viscosity polycrystalline melt enters the capillary, gradually lowering the temperature of the capillary to form single crystals in the capillary; S6. Heating the columnar portion of the reactor near the tapered portion so that the indium antimonide crystals at that location are converted back into a low-viscosity polycrystalline melt; then controlling the heating region of the columnar portion to gradually move upward. During the upward movement of the heating region, the lower polycrystalline melt is recrystallized and induced to form an indium antimonide single crystal having the same crystal orientation as the single crystal in the capillary; In step S1: the molar ratio of indium particles to antimony particles is 1:1; In step S4, the reactor is heated using an electromagnetic induction heating coil, which is movable up and down along the centerline of the reactor; the power of the electromagnetic induction heating coil is controlled to be 1200-1500W; the tapered portion of the reactor is heated to 700-750°C, and the heating rate is controlled to be 20-30°C / min; In step S5, the temperature of the capillary is gradually reduced to 500±0.5°C at a rate of 0.5°C / min; while the temperature is being reduced, an external magnetic field with a strength of 0.2-0.5 Tesla is applied to the outside of the capillary; after 30-45 minutes, the temperature of the capillary is gradually reduced to 400±0.5°C at a rate of 0.5°C / min; In step S6: the electromagnetic induction heating coil is gradually moved upward at a speed of 1-1.2 cm / h; during the upward movement of the electromagnetic induction heating coil, the polycrystalline melt below the electromagnetic induction heating coil is controlled to condense at a speed of 3-5°C / min and recrystallize.

2. The process for synthesizing indium antimonide single crystals in one step according to claim 1, wherein: The center line of the cylindrical portion coincides with the center line of the tapered portion, and the capillary is arranged along the extending direction of the center line; the diameter of the capillary is 1-1.5 mm and the length is 120-150 mm.

3. The process for synthesizing indium antimonide single crystals in one step according to claim 1, characterized in that: In step S1, the inert protective gas is argon; the rotation rate of the reactor is controlled to be 8-10 r / min; and the heating temperature rise rate is controlled to be 5-10° C. / min.

4. The process for synthesizing indium antimonide single crystals in one step according to claim 1, characterized in that: In step S2: the temperature is controlled to be 700-750°C and kept at this temperature for 4-5 hours; then the temperature is increased to 900-950°C at a rate of 25-30°C / min, and the reaction is carried out at this temperature for 4-5 hours; during the process of increasing the temperature to 900-950°C and keeping the temperature, the rotation rate of the reactor is increased to 15-20 r / min.

5. The process for synthesizing indium antimonide single crystals in one step according to claim 1, characterized in that: In step S3: the temperature is lowered to 450-500° C. and maintained for 0.5-1 hour.

6. The process for synthesizing indium antimonide single crystals in one step according to claim 1, characterized in that: Step S5 also includes a step of evacuating the capillary tube.

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