Growth method for improving crystal forming rate of indium phosphide single crystal

Abstract

The invention discloses a growth method for improving the crystal forming rate of indium phosphide single crystals, and belongs to the technical field of crystal growth. The multiple temperature zones are sequentially arranged in the heating furnace from top to bottom in the vertical direction in advance, the temperature of each temperature zone is decreased in a stepped mode, and in the growth process of crystals, the position of the boron nitride crucible is slowly decreased through the lifting system while each temperature zone is controlled to be decreased, so that the growth of the crystals is completed. Therefore, the purposes of effectively adjusting the uniformity of the temperature field and slowly lowering the position of the boron nitride crucible are achieved, slow growth of indium phosphide single crystals is achieved, dislocation can be greatly reduced, and the doping uniformity and the crystallization rate are improved. The technical problems that the indium phosphide single crystal is low in crystallization rate, high in crystal dislocation and uneven in carrier concentration and electron mobility distribution are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal growth, and more particularly to a growth method for improving the crystallization rate of indium phosphide single crystal. Background Art

[0002] Indium phosphide is widely used in the production of RF devices, optical modules, LEDs (Mini LED and Micro LED), lasers, detectors, sensors, space solar cells and other devices. It has broad application space in 5G communications, data centers, new generation displays, artificial intelligence, unmanned driving, wearable devices, aerospace and other fields. Indium phosphide semiconductor materials have a wide bandgap structure, and electrons pass through InP materials at a high speed. Therefore, satellite signal receivers and amplifiers made of indium phosphide chips can operate at extremely high frequencies above 100GHz, and have a wide bandwidth, are less affected by the outside world, and have high stability. Therefore, indium phosphide is a more advanced semiconductor material than gallium arsenide, and it is possible to promote the satellite communication industry to develop to higher frequency bands.

[0003] The technical barriers to the preparation of InP single crystals are high, and the technologies that can enable the mass growth of single crystals mainly include the high-pressure liquid-sealed Czochralski method (LEC) and the vertical temperature gradient solidification method (VGF). The traditional InP single crystals grown by the vertical temperature gradient solidification method (VGF) have a low pass rate, and the diameter is mainly 2" and a small amount of 3", which is difficult to meet the needs of the application market. Although the InP single crystals grown by the high-pressure liquid-sealed Czochralski method (LEC) have a high crystallization rate, they are affected by high dislocations, uneven distribution of carrier concentration and electron mobility, which indirectly affects the application life and cost of high-power microwave devices.

[0004] Therefore, there is an urgent need for a technical solution that can solve the problems of low crystallization rate of indium phosphide single crystals, high crystal dislocations, and uneven distribution of carrier concentration and electron mobility. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a growth method for improving the crystallization rate of indium phosphide single crystals.

[0006] The present invention provides a growth method for improving the crystallization rate of indium phosphide single crystal, comprising: adding indium phosphide polycrystalline material, seed crystal and liquid sealing agent into a boron nitride crucible, then loading the boron nitride crucible into a quartz tube, and then sealing the quartz tube and placing it on a support assembly in a heating furnace; wherein the heating furnace is placed in a pressure vessel in advance, the lower part of the support assembly is fixed on one end of a lifting rod, and the other end of the lifting rod passes through a lower cover of the pressure vessel and is connected to a lifting system; the quartz tube is adjusted to a preset position by the lifting system; wherein a plurality of temperature zones are arranged in sequence from top to bottom in a vertical direction in the heating furnace in advance, and when the quartz tube is in the preset position, the seed crystal in the quartz tube is in the lower half of the plurality of temperature zones, and the shoulder of the quartz tube, the indium phosphide polycrystalline material and the liquid sealing agent are in the lower half of the plurality of temperature zones, and the shoulder of the quartz tube, the indium phosphide polycrystalline material and the liquid sealing agent are in the lower half of the plurality of temperature zones. The method comprises the following steps: the first step is to adjust the temperature of the corresponding temperature zone to completely melt the indium phosphide polycrystalline material, and the second step is to set the initial temperature of each temperature zone and the descending speed of the lifting system; wherein the initial temperatures of the multiple temperature zones decrease from top to bottom, and the temperature of the upper half of the multiple temperature zones is higher than the melting point of the indium phosphide crystal, and the temperature of the lower half of the multiple temperature zones is lower than the melting point of the indium phosphide crystal; the indium phosphide single crystal is started to grow and during the growth process, the temperature of each temperature zone is lowered according to a preset cooling speed, and the lifting system is controlled to lower the quartz tube according to the descending speed until the indium phosphide polycrystalline material completely descends from the upper half of the multiple temperature zones to the lower half and then stops descending, and the crystal growth is terminated after the temperature of all temperature zones is lowered to the preset temperature.

[0007] Optionally, the multiple temperature zones include temperature zone one, temperature zone two, temperature zone three and temperature zone four, temperature zone one and temperature zone two are located in the upper half of the multiple temperature zones, and temperature zone three and temperature zone four are located in the lower half of the multiple temperature zones.

[0008] Optionally, the preset cooling speeds of temperature zone one and temperature zone two are the same, the preset cooling speeds of temperature zone three and temperature zone four are the same, and the preset cooling speeds corresponding to temperature zone one and temperature zone two are smaller than the preset cooling speeds of temperature zone three and temperature zone four.

[0009] Optionally, the preset cooling rate of temperature zone 1 and temperature zone 2 is 0.5°C / h, and the preset cooling rate of temperature zone 3 and temperature zone 4 is 1°C / h.

[0010] Optionally, the descending speed of the lifting system is 1 cm / h.

[0011] Optionally, the initial temperature of temperature zone one is 1088°C~1092°C, the initial temperature of temperature zone two is 1083°C~1087°C, the initial temperature of temperature zone three is 1020°C~1030°C, and the initial temperature of temperature zone four is 1000°C~1010°C.

[0012] Optionally, the operation of adjusting the temperature of the corresponding temperature zone to completely melt the indium phosphide polycrystalline material includes: controlling the temperature of the upper half of the multiple temperature zones to be higher than the melting point of the indium phosphide crystal through a heating device, and controlling the temperature of the lower half of the multiple temperature zones to be lower than or equal to 1040° C., and maintaining it for more than 20 hours until the indium phosphide polycrystalline material is completely melted.

[0013] Optionally, the support assembly includes a support tube and a support tray; wherein the support tube is arranged on the support tray for placing the quartz tube; and the support tray is fixed on the lifting rod.

[0014] Optionally, adding indium phosphide polycrystalline material, seed crystal and liquid sealing agent into a boron nitride crucible, then loading the boron nitride crucible into a quartz tube, and then sealing the quartz tube and placing it on a support assembly in a heating furnace, the operation includes: cleaning the indium phosphide polycrystalline material, placing it in a clean oven for drying, the oven temperature is 100-120°C, and the drying time is 12 hours; cleaning the quartz tube, quartz cap, and boron nitride crucible, and placing them on a clean workbench in a Class 100 clean room to dry; loading the dried indium phosphide polycrystalline material and liquid sealing agent into the boron nitride crucible; loading the loaded boron nitride crucible into the quartz tube, and then installing the quartz tube and the quartz cap on a vacuum tube sealing furnace to seal the quartz tube mouth; placing the loaded quartz tube on the support assembly in the heating furnace; after the quartz tube is placed, using the heating furnace to plug the furnace mouth of the heating furnace.

[0015] Optionally, before adjusting the quartz tube to a preset position by the lifting system, the method further includes: filling the heating furnace with inert gas, and the filling pressure reaches 2.7 MPa.

[0016] The present invention achieves slow growth of indium phosphide single crystal by effectively adjusting the uniformity of the temperature field and slowly lowering the position of the boron nitride crucible, which can greatly reduce dislocations and improve the uniformity of doping and the crystallization rate. The technical problems of low crystallization rate, high crystal dislocation, and uneven distribution of carrier concentration and electron mobility of indium phosphide single crystal are effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings: Figure 1 It is a schematic flow chart of a growth method for improving the crystallization rate of indium phosphide single crystal according to an embodiment of the present invention; Figure 2 It is a front cross-sectional view of an apparatus for growing an indium phosphide single crystal according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0019] Combination Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a growth method for improving the crystallization rate of indium phosphide single crystal, comprising the following steps: Step S1: adding indium phosphide polycrystalline material, seed crystal and liquid sealing agent into a boron nitride crucible, then placing the boron nitride crucible into a quartz tube, and then sealing the quartz tube and placing it on a support assembly in a heating furnace; wherein the heating furnace is placed in a pressure vessel in advance, the lower side of the support assembly is fixed on one end of a lifting rod, and the other end of the lifting rod passes through a lower cover of the pressure vessel and is connected to a lifting system; Step S2: adjusting the quartz tube to a preset position by a lifting system; wherein a plurality of temperature zones are pre-set in sequence from top to bottom in the vertical direction of the heating furnace, and when the quartz tube is at the preset position, the seed crystal in the quartz tube is in the lower half of the plurality of temperature zones, and the shoulder of the quartz tube, the indium phosphide polycrystalline material and the liquid sealing agent are in the upper half of the plurality of temperature zones; Step S3: adjusting the temperature of the corresponding temperature zone to completely melt the indium phosphide polycrystalline material, and then setting the initial temperature of each temperature zone and the descending speed of the lifting system; wherein the initial temperatures of the plurality of temperature zones decrease from top to bottom, and the temperature of the upper half of the plurality of temperature zones is higher than the melting point of the indium phosphide crystal, and the temperature of the lower half of the plurality of temperature zones is lower than the melting point of the indium phosphide crystal; Step S4: Start growing an indium phosphide single crystal and during the growth process, lower the temperature of each temperature zone according to a preset cooling rate, and at the same time control the lifting system to lower the quartz tube at a descending rate until the indium phosphide polycrystalline material completely descends from the upper half of the multiple temperature zones to the lower half and then stops descending. After the temperature of all temperature zones drops to the preset temperature, the crystal growth is terminated.

[0020] Specifically, combined Figure 2As shown, in this embodiment, the indium phosphide polycrystalline material 1, the seed crystal and the liquid sealant are first added to the boron nitride crucible (not shown in the figure), and then the boron nitride crucible is placed in the quartz tube 2, and then the quartz tube 2 is sealed and placed on the support assembly in the heating furnace. The support assembly is, for example, Figure 2 The heating furnace is placed in the pressure vessel 3 in advance, and the lower part of the support assembly is fixed on one end of the lifting rod 10, and the other end of the lifting rod 10 passes through the lower cover of the pressure vessel 3 and is connected to the lifting system 9.

[0021] Then, the quartz tube 2 is adjusted to a preset position by the lifting system 9; wherein, a plurality of temperature zones are pre-set in the vertical direction from top to bottom in the heating furnace. In a specific embodiment, the plurality of temperature zones include, for example but not limited to, temperature zone 1 4, temperature zone 2 5, temperature zone 3 6 and temperature zone 4 7. When the quartz tube 2 is in the preset position, the seed crystal in the quartz tube 2 is in the lower half of the plurality of temperature zones, and the shoulder of the quartz tube 2, the indium phosphide polycrystalline material and the liquid sealant are in the upper half of the plurality of temperature zones. wherein, Figure 2 It is not a schematic diagram of the device when the quartz tube 2 is in the preset position, but a schematic diagram of the device after the quartz tube 2 has been lowered from the preset position to a certain height during the crystal growth process. In addition, the multiple temperature zones are not limited to 4 temperature zones, and can be 6 temperature zones, or 8 temperature zones, or other number of temperature zones.

[0022] Secondly, the temperature of the corresponding temperature zone can be adjusted by the heating device to completely melt the indium phosphide polycrystalline material 1, and then the initial temperature of each temperature zone and the descending speed of the lifting system 9 are set. The initial temperatures of the multiple temperature zones decrease from top to bottom, and the temperature of the upper half of the multiple temperature zones is higher than the melting point of the indium phosphide crystal, and the temperature of the lower half of the multiple temperature zones is lower than the melting point of the indium phosphide crystal.

[0023] Finally, the growth of indium phosphide single crystal begins and during the growth process, the temperature of each temperature zone is lowered according to the preset cooling rate, and the lifting system 9 is controlled to lower the quartz tube 2 according to the descending speed until the indium phosphide polycrystalline material 1 completely descends from the upper half of the multiple temperature zones to the lower half and then stops descending. After the temperature of all temperature zones is reduced to the preset temperature, the crystal growth is terminated.

[0024] Optionally, the preset cooling speeds of temperature zone one and temperature zone two are the same, the preset cooling speeds of temperature zone three and temperature zone four are the same, and the preset cooling speeds corresponding to temperature zone one and temperature zone two are smaller than the preset cooling speeds of temperature zone three and temperature zone four.

[0025] Optionally, the preset cooling rate of temperature zone 1 and temperature zone 2 is 0.5°C / h, and the preset cooling rate of temperature zone 3 and temperature zone 4 is 1°C / h.

[0026] Optionally, the descending speed of the lifting system is 1 cm / h.

[0027] Optionally, the initial temperature of temperature zone one is 1088°C~1092°C, the initial temperature of temperature zone two is 1083°C~1087°C, the initial temperature of temperature zone three is 1020°C~1030°C, and the initial temperature of temperature zone four is 1000°C~1010°C.

[0028] In a specific embodiment, the initial temperature of temperature zone 1 4 is 1090°C, the initial temperature of temperature zone 2 5 is 1085°C, the initial temperature of temperature zone 3 is 1020°C, and the initial temperature of temperature zone 4 is 1000°C.

[0029] In a specific embodiment, the operation of adjusting the temperature of the corresponding temperature zone to completely melt the indium phosphide polycrystalline material includes: controlling the temperature of the upper half of the multiple temperature zones to be higher than the melting point of the indium phosphide crystal through a heating device, and controlling the temperature of the lower half of the multiple temperature zones to be lower than or equal to 1040° C., and maintaining it for more than 20 hours until the indium phosphide polycrystalline material is completely melted.

[0030] In a specific embodiment, Figure 2 As shown, an indium phosphide polycrystalline material 1, a seed crystal and a liquid sealing agent are added to a boron nitride crucible, and then the boron nitride crucible is loaded into a quartz tube 2, and then the quartz tube 2 is sealed and placed on a support assembly in a heating furnace, including: cleaning the indium phosphide polycrystalline material 1, and drying it in a clean oven, the oven temperature is 100-120°C, and the drying time is 12h; cleaning the quartz tube 2, the quartz cap, and the boron nitride crucible, and placing them on a clean workbench in a Class 100 clean room to dry; loading the dried indium phosphide polycrystalline material 1 and the liquid sealing agent into the boron nitride crucible; loading the loaded boron nitride crucible into the quartz tube 2, and then installing the quartz tube 2 and the quartz cap on a vacuum tube sealing furnace to seal the quartz tube mouth; placing the loaded quartz tube 2 on the support assembly in the heating furnace; after the quartz tube is placed, using the heating furnace to plug the furnace mouth of the heating furnace.

[0031] Optionally, before adjusting the quartz tube to a preset position by the lifting system, the method further includes: filling the heating furnace with inert gas, and the filling pressure reaches 2.7 MPa.

[0032] Therefore, by effectively adjusting the uniformity of the temperature field and slowly lowering the position of the boron nitride crucible, the slow growth of the indium phosphide single crystal can be achieved, which can greatly reduce dislocations and improve the uniformity of doping and the crystallization rate. The technical problems of low crystallization rate, high crystal dislocation, and uneven distribution of carrier concentration and electron mobility of indium phosphide single crystal are effectively solved.

[0033] Example 1 The method proposed in this embodiment is used to grow multiple furnaces of indium phosphide single crystals: 1. Clean 5kg of indium phosphide polycrystalline material and dry it in a clean oven at a temperature of 100-120 degrees Celsius for 12 hours; 2. Clean the quartz tube, quartz cap and boron nitride crucible and place them on a clean workbench in a Class 100 clean room to dry; 3. Load the dried indium phosphide polycrystalline material and boron oxide into the boron nitride crucible. Load as much indium phosphide polycrystalline as possible without dropping it. Then load the loaded boron nitride crucible into the quartz tube, and then install the quartz tube and quartz cap on the vacuum tube sealing furnace to seal the quartz tube mouth to ensure that there is no leakage and cracks; 4. Load the loaded quartz tube into the heating furnace. The quartz tube should be securely placed on the high temperature resistant support tube. The support tube is installed on the support tray. The support tray is fixed on the lifting rod. One end of the lifting rod is connected to the lifting and rotating system. At the same time, the support rod passes through the lower cover of the pressure chamber, and a sealing ring is used to seal the lifting rod and the lower cover. 5. After the quartz tube is installed, plug the furnace mouth of the heating furnace with the heating furnace plug to ensure that the temperature will not leak from the upper cover. The heating furnace plug is made of a kind of high-temperature resistant cotton with good heat preservation to ensure the stability of the temperature in the heating furnace; 6. After the installation is complete, fill the furnace with inert gas to 2.7MPa. The gas filled into the furnace is inert gas nitrogen or argon; 7. Adjust the quartz tube to a suitable position through the lifting system, and then turn on the heating control of the four heating zones of the heating furnace to make the temperature of temperature zone 1 and temperature zone 2 reach above 1070 degrees Celsius to melt the indium phosphide polycrystal. The temperature of temperature zones 3 and 4 cannot exceed 1040 degrees Celsius to ensure that the seed crystal cannot be completely melted. Maintain for more than 20 hours. After the indium phosphide polycrystal material is completely melted, set temperature zone 1 at about 1090 degrees Celsius, temperature zone 2 at about 1085 degrees Celsius, temperature zone 3 at 1020 degrees Celsius, and temperature zone 4 at 1000 degrees Celsius. Set the descending speed of the lifting system at a descending speed of 1 cm / h, and prepare to start the growth of indium phosphide single crystals; 8. Slowly lower the temperature of the four temperature zones to above 1070 degrees Celsius in temperature zone 1 and temperature zone 2, with a cooling rate of 10 degrees Celsius in 20 hours, and the temperature of temperature zone 3 and temperature zone 4 to below 1000 degrees Celsius, with a cooling rate of 20 degrees Celsius in 20 hours. At the same time, start the quartz tube descent program, and slowly lower the quartz tube from temperature zones 1 and 2 to temperature zones 3 and 4 at a set descent rate of 1 cm / h; 9. After the polycrystalline material of the quartz tube has completely dropped from temperature zones 1 and 2 to temperature zones 3 and 4, close the descending program, and use more than 20 hours to reduce the temperature from temperature zones 1 to 4 to below 100 degrees Celsius, then stop heating, completely exhaust the gas in the furnace, open the upper cover, and take the furnace out; the cooling speed of reducing the temperature from temperature zones 1 to 4 to 100 degrees Celsius cannot be too fast to prevent crystal stress, which will cause cracks in the crystal. 10. After taking out the crystal, cut the head and tail into slices, observe the growth, and take samples to test whether various indicators are qualified.

[0034] Example 2 The method proposed in this embodiment is used to grow multiple furnaces of indium phosphide single crystals: 1. Clean 6kg of indium phosphide polycrystalline material and dry it in a clean oven at a temperature of 100-120 degrees Celsius for 12 hours; 2. Clean the quartz tube, quartz cap and boron nitride crucible and place them on a clean workbench in a Class 100 clean room to dry; 3. Load the dried indium phosphide polycrystalline material and boron oxide into the boron nitride crucible. Load as much indium phosphide polycrystalline as possible without dropping it. Then load the loaded boron nitride crucible into the quartz tube, and then install the quartz tube and quartz cap on the vacuum tube sealing furnace to seal the quartz tube mouth to ensure that there is no leakage and cracks; 4. Load the loaded quartz tube into the heating furnace. The quartz tube should be securely placed on the high temperature resistant support tube. The support tube is installed on the support tray. The support tray is fixed on the lifting rod. One end of the lifting rod is connected to the lifting and rotating system. At the same time, the support rod passes through the lower cover of the pressure chamber, and a sealing ring is used to seal the lifting rod and the lower cover. 5. After the quartz tube is installed, plug the furnace mouth of the heating furnace with the heating furnace plug to ensure that the temperature will not leak from the upper cover. The heating furnace plug is made of a kind of high-temperature resistant cotton with good heat preservation to ensure the stability of the temperature in the heating furnace; 6. After the installation is complete, fill the furnace with inert gas to 2.7MPa. The gas filled into the furnace is inert gas nitrogen or argon; 7. Adjust the quartz tube to a suitable position through the lifting system, and then turn on the heating control of the four heating zones of the heating furnace to make the temperature of temperature zone 1 and temperature zone 2 reach above 1070 degrees Celsius to melt the indium phosphide polycrystal. The temperature of temperature zones 3 and 4 cannot exceed 1040 degrees Celsius to ensure that the seed crystal cannot be completely melted. Maintain for more than 20 hours. After the indium phosphide polycrystal material is completely melted, set temperature zone 1 at about 1092 degrees Celsius, temperature zone 2 at about 1083 degrees Celsius, temperature zone 3 at 1015 degrees Celsius, and temperature zone 4 at 1050 degrees Celsius. Set the descending speed of the lifting system at a descending speed of 1 cm / h, and prepare to start the growth of indium phosphide single crystals; 8. Slowly lower the temperature of the four temperature zones to above 1070 degrees Celsius in temperature zone 1 and temperature zone 2, with a cooling rate of 10 degrees Celsius in 20 hours, and the temperature of temperature zone 3 and temperature zone 4 to below 1000 degrees Celsius, with a cooling rate of 20 degrees Celsius in 20 hours. At the same time, start the quartz tube descent program, and slowly lower the quartz tube from temperature zones 1 and 2 to temperature zones 3 and 4 at a set descent rate of 1 cm / h; 9. After the polycrystalline material of the quartz tube has completely dropped from temperature zones 1 and 2 to temperature zones 3 and 4, close the descending program, and use more than 20 hours to reduce the temperature from temperature zones 1 to 4 to below 100 degrees Celsius, then stop heating, completely exhaust the gas in the furnace, open the upper cover, and take the furnace out; the cooling speed of reducing the temperature from temperature zones 1 to 4 to 100 degrees Celsius cannot be too fast to prevent crystal stress, which will cause cracks in the crystal. 10. After taking out the crystal, cut the head and tail into slices, observe the growth, and take samples to test whether various indicators are qualified.

[0035] Comparative Example 1 Growing multiple furnaces of InP single crystals using existing methods: 1. Place the indium phosphide polycrystalline raw material into a crucible and assemble a single crystal growth furnace for high temperature annealing; 2. Heating the melt, setting the heating target value in the heating control program for heating and pressurizing; Melt seed growth, setting the growth temperature, and starting crystal growth until the raw materials are consumed; 3. Cooling annealing: After the growth is completed, the furnace automatically enters the cooling annealing process. After the temperature drops to 350°C, the air pressure in the furnace is vented. After the temperature in the furnace drops to about 150°C, the furnace door is opened to obtain the single crystal.

[0036] 4. After taking out the crystal, cut the head and tail into slices, observe the growth, and take samples to test whether various indicators are qualified.

[0037] Afterwards, the indium phosphide single crystals grown using the methods described in Example 1, Example 2 and Comparative Example 1 were tested to obtain the data comparison table shown in Table 1.

[0038] Table 1 Example 1 Example 2 Comparative Example 1 Single crystal size 4 inches 4 inches 4 inches Crystal dislocation 8 7 15 Crystallization rate ＞60% ＞60% ＜30% The results in Table 1 show that the product quality of the indium phosphide single crystal produced by the crystal growth method proposed in the present application is good, the dislocation defect is less than 10, and the crystallization rate is greater than 60%.

[0039] In summary, the present invention achieves slow growth of indium phosphide single crystals by effectively adjusting the uniformity of the temperature field and slowly lowering the position of the boron nitride crucible, which can greatly reduce dislocations and improve the uniformity of doping and the crystallization rate. In addition, the equipment of this method has a high crystallization rate, easy temperature control, simple operation, and high single crystal quality, which can greatly improve efficiency and reduce costs. It effectively solves the technical problems of low crystallization rate of indium phosphide single crystals, high crystal dislocations, and uneven distribution of carrier concentration and electron mobility.

[0040] The foregoing examples are merely illustrative and are used to explain some features of the method of the present invention. The appended claims are intended to claim the widest possible range that can be conceived, and the embodiments presented herein are only illustrations of selected implementations according to the combination of all possible embodiments. Therefore, it is the applicant's intention that the appended claims are not limited by the selection of examples that illustrate the features of the present invention. Some numerical ranges used in the claims also include sub-ranges within them, and changes in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A method for increasing the crystallization rate of indium phosphide single crystals, characterized in that: include: Adding indium phosphide polycrystalline material, seed crystal and liquid sealing agent into a boron nitride crucible, then placing the boron nitride crucible into a quartz tube, and then sealing the quartz tube and placing it on a support assembly in a heating furnace; wherein the heating furnace is pre-placed in a pressure vessel, the lower side of the support assembly is fixed on one end of a lifting rod, and the other end of the lifting rod passes through the lower cover of the pressure vessel and is connected to a lifting system; The quartz tube is adjusted to a preset position by the lifting system; wherein a plurality of temperature zones are pre-set in sequence from top to bottom in the vertical direction of the heating furnace, and when the quartz tube is at the preset position, the seed crystal in the quartz tube is at the lower half of the plurality of temperature zones, and the shoulder of the quartz tube, the indium phosphide polycrystalline material and the liquid sealant are at the upper half of the plurality of temperature zones; Adjusting the temperature of the corresponding temperature zone to completely melt the indium phosphide polycrystalline material, and then setting the initial temperature of each temperature zone and the descending speed of the lifting system; wherein the initial temperatures of the plurality of temperature zones decrease in sequence from top to bottom, and the temperature of the upper half of the plurality of temperature zones is higher than the melting point of the indium phosphide crystal, and the temperature of the lower half of the plurality of temperature zones is lower than the melting point of the indium phosphide crystal; The growth of an indium phosphide single crystal begins, and during the growth process, the temperature of each temperature zone is lowered according to a preset cooling rate, and at the same time, the lifting system is controlled to lower the quartz tube according to the descending rate until the indium phosphide polycrystalline material completely descends from the upper half of the multiple temperature zones to the lower half and then stops descending. After the temperatures of all temperature zones are lowered to the preset temperature, the crystal growth is terminated.

2. The method according to claim 1, characterized in that The multiple temperature zones include temperature zone one, temperature zone two, temperature zone three and temperature zone four. The temperature zone one and the temperature zone two are located in the upper half of the multiple temperature zones, and the temperature zone three and the temperature zone four are located in the lower half of the multiple temperature zones.

3. The method according to claim 2, characterized in that The preset cooling speeds of the temperature zone 1 and the temperature zone 2 are the same, the preset cooling speeds of the temperature zone 3 and the temperature zone 4 are the same, and the preset cooling speeds corresponding to the temperature zone 1 and the temperature zone 2 are smaller than the preset cooling speeds of the temperature zone 3 and the temperature zone 4.

4. The method according to claim 3, characterized in that The preset cooling speed of the temperature zone 1 and the temperature zone 2 is 0.5°C / h, and the preset cooling speed of the temperature zone 3 and the temperature zone 4 is 1°C / h.

5. The method according to claim 1, characterized in that The descending speed of the lifting system is 1 cm / h.

6. The method according to claim 2, characterized in that The initial temperature of the temperature zone one is 1088°C to 1092°C, the initial temperature of the temperature zone two is 1083°C to 1087°C, the initial temperature of the temperature zone three is 1020°C to 1030°C, and the initial temperature of the temperature zone four is 1000°C to 1010°C.

7. The method according to claim 1, characterized in that The operation of adjusting the temperature of the corresponding temperature zone to completely melt the indium phosphide polycrystalline material includes: The temperature of the upper half of the multiple temperature zones is controlled by a heating device to be higher than the melting point of the indium phosphide crystal, and the temperature of the lower half of the multiple temperature zones is controlled to be lower than or equal to 1040° C., and maintained for more than 20 hours until the indium phosphide polycrystalline material is completely melted.

8. The method according to claim 1, characterized in that The support assembly includes a support tube and a support tray; wherein the support tube is arranged on the support tray for being placed on the quartz tube; and the support tray is fixed on the lifting rod.

9. The method according to claim 1, characterized in that: The operation of adding the indium phosphide polycrystalline material, the seed crystal and the liquid sealing agent into the boron nitride crucible, then placing the boron nitride crucible into a quartz tube, and then sealing the quartz tube and placing it on a support assembly in a heating furnace includes: Clean the indium phosphide polycrystalline material and dry it in a clean oven at a temperature of 100-120°C for 12 hours; Clean the quartz tube, quartz cap, and boron nitride crucible and place them on a clean workbench in a Class 100 clean room to dry; Putting the dried indium phosphide polycrystalline material and the liquid sealing agent into the boron nitride crucible; Put the loaded boron nitride crucible into the quartz tube, and then install the quartz tube and the quartz cap on the vacuum tube sealing furnace to seal the quartz tube opening; Place the loaded quartz tube on the support assembly in the heating furnace; After the quartz tube is placed, the furnace port of the heating furnace is tightly plugged using a heating furnace plug.

10. The method according to claim 1, characterized in that Before adjusting the quartz tube to the preset position by the lifting system, the method further includes: filling the heating furnace with inert gas, and the filling pressure reaches 2.7 MPa.

Images