A growth apparatus and a growth method for growing a bulk crystal by a dielectric waveguide method

Abstract

This invention provides a growth apparatus and method for growing large-volume crystals using a guided-mold method. The apparatus includes a furnace body, a crucible, a growth mold, and a lifting system. By designing a low-height growth mold and raising the crucible, continuous and full utilization of the molten raw material is achieved during crystal growth. Increasing the crucible height increases the raw material capacity, reducing the amount of temperature field structure material used and power consumption. During the loading process, the crucible is lowered to the bottom of the mold, reducing the space occupied by the mold and enabling one-time loading, saving crystal growth time and molten energy consumption. The growth method includes temperature field installation and loading, growth mold and seed crystal installation, and crystal growth. This invention overcomes the problems of high cost and high growth process risk associated with existing guided-mold methods for growing large-volume crystals, enabling low-cost, low-risk guided-mold growth of large-volume crystals.

Description

Technical Field

[0001] This invention relates to a growth apparatus and method for growing large-volume crystals using a guided-mode method, which enables low-cost, low-risk growth process growth of large-volume crystals using a guided-mode method, and belongs to the field of crystal growth technology. Background Technology

[0002] The guided-mold method, an advanced near-size crystal growth technique, determines the cross-sectional shape and size of the crystal by the shape and size of the top edge of the crystal growth mold. It allows for the direct drawing of filaments, tubes, rods, sheets, plates, and various other special shapes from the melt. Therefore, crystals prepared using this method eliminate the need for arduous cutting and shaping processes in subsequent manufacturing, significantly reducing material waste, saving processing time, and lowering product costs. It has been widely used in the industrial production of silicon, germanium, and sapphire crystals.

[0003] In recent years, the guided-mold method has developed rapidly, giving rise to technologies such as multi-crystal synchronous growth, large-size plate-shaped crystal growth, and thick-walled tubular crystal growth. These technologies are characterized by high single-furnace crystal yield and large crystal volume, thus requiring crucibles with large volumes to hold more growth material. In guided-mold crystal growth, the transport of molten material utilizes the principle of liquid level rise in a capillary tube. The melt in the crucible rises along the feed slit of the growth mold, and its rising height depends on the melt surface tension, melt density, and slit radius. In general guided-mold growth technologies, the growth mold is usually fixed inside the crucible, with its height, width, or outer diameter being comparable to the crucible size. During growth, the distance between the end face of the growth mold and the upper surface of the melt gradually increases, which can cause insufficient feed, inability to continue crystal growth, and incomplete utilization of raw materials, making it difficult to achieve the growth of multi-crystal, large-size, or thick-walled tubular crystals.

[0004] To address the aforementioned issues, crucibles with a larger diameter and lower height relative to the growth mold (typically a diameter-to-height ratio greater than 2:1) are often used. This increases the crucible's cross-sectional area, thereby increasing its volume to meet the raw material requirements for large-volume crystal growth and ensure continuous material supply during the growth process. Large-diameter crucible crystal growth processes require large-scale structural temperature fields, which not only increases the amount of materials consumed in the temperature field but also significantly increases the power consumption and process risks associated with crystal growth. Furthermore, the growth mold occupies a large amount of crucible space, affecting the volume of raw materials held within the crucible and increasing the difficulty of raw material placement. This often necessitates secondary loading and melting of the raw materials, increasing both time and economic costs. Therefore, existing growth apparatus and methods for growing large-volume crystals using the guide mold method suffer from high growth costs and significant process risks. Summary of the Invention

[0005] To address the problems of high cost and high process risk associated with existing mold-guided methods for growing large-volume crystals, this invention provides a mold-guided crystal growth device and method with a low-height growth mold and a liftable crucible with a small diameter / height ratio (less than 1:1). By designing a low-height growth mold and raising the crucible, the growth mold remains in constant contact with the melt during crystal growth, ensuring continuous and full utilization of the melt raw material. With a fixed crucible diameter, increasing the crucible height increases the raw material capacity, reducing the amount of temperature field structure material and power consumption. During the loading process, the crucible is lowered to the bottom of the mold, reducing the space occupied by the mold and enabling one-time loading, saving crystal growth time and melt energy consumption. This invention overcomes the problems of high cost and high process risk associated with existing mold-guided methods for growing large-volume crystals, enabling low-cost, low-process-risk mold-guided crystal growth.

[0006] The technical solution of the present invention is as follows:

[0007] A growth apparatus for growing large-volume crystals using a guided mold method includes a furnace body, a crucible, a growth mold, and a lifting system.

[0008] A heat insulation plate is installed at the bottom of the furnace cavity, with a circular hole in the center for the transmission rod of the lifting system to pass through. A vertical through hole is provided at the top of the furnace body for the seed crystal rod to pass through the furnace body and connect to the lifting system and the weighing system. An air inlet is provided at the bottom of the furnace body, and an air outlet is provided at the top. The crucible is used to heat and hold the crystal growth raw materials, and an induction coil and a heat preservation screen are provided around the crucible. The growth mold is fixed to the top of the furnace chamber, and a crucible cover plate of the same material as the mold is fixed to the side of the mold. The lifting system consists of a transmission rod and a lifting drive motor. A heat-insulated support base plate is fixed to the upper part of the transmission rod, and the crucible is placed on the heat-insulated support base plate.

[0009] According to the present invention, preferably, the growth mold is less than 20mm in height, and can be designed as a plate or tube according to the shape of the crystal to be grown, and is fixed to the top of the furnace body by a connecting rod. The upper surface of the growth mold is horizontal and flush with the upper surface of the induction coil. The growth mold is made of iridium, platinum, tungsten or molybdenum.

[0010] According to the present invention, preferably, the transmission rod is a cylindrical corundum rod with a diameter of 20-50mm (e.g., a diameter of 20mm, 21mm, 30mm, 40mm, 49mm or 50mm); the lifting motor is a servo motor with a positioning accuracy better than 0.01mm, so as to realize the stable lifting of the crucible;

[0011] According to the present invention, preferably, the crucible is made of iridium, platinum, tungsten, or molybdenum, and the crucible is cylindrical with an internal height greater than its internal diameter; the heat insulation plate and the heat preservation screen are made of zirconium oxide, tungsten, molybdenum, or graphite.

[0012] According to the present invention, preferably, the crystal growth apparatus of the guided mold method also has an automatic equal diameter control system for weighing, model JGD80.

[0013] This invention also discloses a method for growing crystals using a growth apparatus employing the guided-mode method to grow large-volume crystals, comprising the following steps:

[0014] (1) Temperature field installation and loading

[0015] According to the temperature field structure design, the crucible and each temperature field component are installed in sequence. The temperature field structure and the crucible are horizontal after installation and are concentric with each other. The prepared crystal growth raw material is placed in the crucible. The temperature field structure includes a bottom heat preservation screen, a side heat preservation screen and an upper heat preservation cover.

[0016] (2) Growth mold and seed crystal installation

[0017] Based on the crystal to be grown, select an oriented seed crystal, cut it into shape according to the design, and fix it on the seed crystal rod; fix the growth mold on the top of the furnace body, adjust the position of the seed crystal and the growth mold to ensure that the seed crystal is vertical and perpendicular to the top end face of the growth mold, and that both, the crucible, and the temperature field are symmetrical about the same center.

[0018] (3) Crystal growth

[0019] Vacuum up to 10 -3 Pa, fill with high-purity inert nitrogen or argon to 1 atmosphere, use medium-frequency induction heating crucible, automatically increase power at a rate of 100-1000W / h to melt the raw material, after the raw material is completely melted, continue to increase the power by 20-500W, maintain constant power for 1-10h, then reduce to the power at the time of raw material melting, continue to maintain constant power for 1-3h, automatically control crystal growth using the mold method, the crucible rises at a rate calculated by the program during the automatic growth process;

[0020] According to the present invention, preferably, the raw material in step (1) is polycrystalline powder, which is pressed into a cake shape, column shape, etc., and placed in a crucible; when the raw material is placed in, the position of the crucible is adjusted in real time according to the temperature field structure and the height of the raw material, and the growth mold and the cover plate are positioned above the crucible opening;

[0021] According to the present invention, preferably, the lower end of the seed crystal in step (2) is designed and cut into shapes such as square strips, vertical sheets, and horizontal plates;

[0022] According to the present invention, preferably, when growing crystals using the guided mold method in step (3), the crucible is first raised at a rate of 5-100 mm / h until the bottom of the growth mold contacts the melt interface, and then raised at a rate of 5-50 mm / h. After each 1-2 mm increase, the crucible is paused for 10-30 minutes until the upper surface of the growth mold is filled with melt. The crucible is then raised to allow seeding. The seed crystal is lowered slowly at a rate of 10-300 mm / h until it contacts the melt. The power is adjusted until the weight signal of the weighing system stabilizes, and then the growth is automatically controlled. The automatic growth is controlled by the upper weighing automatic equal diameter control system. The crucible rising rate u is determined by dividing the crystal growth weight rate g by the product of the crystal density ρ and the cross-sectional area s inside the crucible, i.e., u = g / (ρ*s), so as to achieve continuous material supply.

[0023] According to the present invention, preferably, in step (3), after the crystal grows to the required size, the automatic control growth is stopped, and the power is increased by 100-500W at a rate of 50-200W / h, and the power is kept constant for 1-2 hours. Then, the crystal is removed from the melt at a rate of 50-600mm / h. After the crystal is removed, the power is reduced to 0W at a rate of 20-1000W / h, and a single crystal is obtained.

[0024] For any content not described in detail in this invention, please refer to the existing general techniques in this field.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention improves and designs a low-height growth mold and a liftable small-diameter / high-ratio crucible for crystal growth using the guided mold method, based on the general mold and growth technology of guided mold method. By designing a low-height growth mold and raising the crucible, the growth mold remains in constant contact with the melt during crystal growth, ensuring continuous and full utilization of the melt raw material. Increasing the crucible height increases the raw material capacity, reducing the amount of temperature field structure material and power consumption. During the loading process, the crucible is lowered to the bottom of the mold, reducing the space occupied by the mold and enabling one-time loading, saving crystal growth time and melt energy consumption. This invention enables low-cost, low-risk guided mold method growth of large-volume crystals. Attached Figure Description

[0027] To illustrate the present invention more clearly, the accompanying drawings used in the description of the prior art will be briefly introduced below.

[0028] Figure 1 This is a schematic diagram of the crystal growth apparatus of the present invention.

[0029] In the diagram: 1. Drive rod; 2. Air inlet; 3. Furnace body; 4. Bottom insulation screen; 5. Side insulation screen; 6. Insulated load-bearing base plate; 7. Induction coil; 8. Crucible; 9. Crystal growth raw material; 10. Growth mold; 11. Crucible cover; 12. Seed crystal; 13. Seed crystal rod; 14. Upper insulation cover; 15. Air outlet. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, but are not limited thereto.

[0031] Example 1

[0032] like Figure 1 As shown, the present invention discloses a crystal growth device using a low-height growth mold and a liftable crucible with a small diameter / height ratio (diameter / height ratio less than 1:1), comprising a furnace body 3, a crucible 8, a growth mold 10 and a transmission system, which can realize the growth of large-volume crystals using the mold method with low cost and low growth process risk.

[0033] A bottom insulation screen 4 is installed at the bottom of the furnace body cavity. The bottom insulation screen has a central hole for the transmission rod 1 of the transmission system to pass through. The transmission system consists of the transmission rod 1 and a lifting drive motor (not shown in the figure). A heat-insulating load-bearing base plate 6 is fixed to the upper part of the transmission rod 1, and a crucible 8 is placed on the heat-insulating load-bearing base plate 6. The crucible 8 is used for heating and holding the crystal growth raw material 9. An induction coil 7 and a side insulation screen 5 are arranged around the crucible. The growth mold 10 is fixed to the top of the furnace body 3, and the crucible cover 11 is fixed to the side of the growth mold 10. The seed crystal rod 13 passes through the top of the furnace body 3 and connects to the lifting system and weighing system (not shown in the figure) outside the furnace body 3. An air inlet 2 is provided at the bottom of the furnace body 3, and an air outlet 15 is provided at the top. A seed crystal 12 is installed at the bottom of the seed crystal rod 13. A vertical through hole is provided at the top of the furnace body for the seed crystal rod to pass through the furnace body and connect to the lifting system and weighing system. The seed crystal rod 13 passes through a vertical through hole at the top of the furnace body 3 and extends into the growth mold 10. The crucible cover plate 11 is made of the same material as the growth mold.

[0034] The growth mold is less than 20mm in height. Depending on the shape of the crystal, it can be designed as a plate or a tube and fixed to the top of the furnace body by a connecting rod. The upper surface of the growth mold is horizontal and flush with the upper surface of the induction coil 7. The growth mold is made of iridium, platinum, tungsten or molybdenum.

[0035] For example, the crystal growth mold 10 is a plate-shaped crystal growth mold or a tubular crystal growth mold. The crucible has an internal diameter of 100 mm and an internal height of 200 mm; the plate-shaped crystal growth mold has a height of 15 mm, a length of 60 mm, a width of 10 mm, and a through-hole length of 56 mm and a width of 0.5 mm; the tubular crystal growth mold has a height of 18 mm, an outer diameter of 60 mm, an inner diameter of 54 mm, and a through-hole width of 0.5 mm; the crucible cover has an outer diameter of 98 mm.

[0036] The transmission rod 1 is a cylindrical corundum rod with a diameter of 20-50mm; the lifting drive motor is a servo motor with a positioning accuracy better than 0.01mm, realizing the stable lifting of the crucible;

[0037] The crucible 8 is made of iridium, platinum, tungsten, or molybdenum, and is cylindrical with an internal height greater than its internal diameter; the bottom insulation screen 4, the heat-insulating load-bearing base plate 6, and the side insulation screen 5 are made of zirconium oxide, tungsten, molybdenum, or graphite.

[0038] The crystal growth apparatus for the guided mold method also has an automatic equal diameter control system for weighing, model JGD80, which includes a crucible lifting control module.

[0039] Example 2

[0040] The method for growing a plate-shaped Nd:YLF crystal with a constant diameter width of 52 mm, a thickness of 8 mm, and a length of 150 mm using the guided crystal growth apparatus provided in Example 1 includes the following steps:

[0041] (1) Temperature field installation and loading

[0042] According to the temperature field structure design, install the graphite crucible and the bottom insulation screen, side insulation screen, top insulation cover and other temperature field structure graphite components in sequence. After installation, the temperature field structure components and crucible are horizontal and concentric with each other. Place the prepared columnar Nd:YLF polycrystalline growth raw material into the crucible.

[0043] (2) Growth mold and seed crystal installation

[0044] Nd:LYF crystals with the

[100] crystal orientation were selected and cut into 5mm×5mm square strips as seed crystals and fixed on the seed crystal rod; the plate-shaped platinum crystal growth mold was fixed on the top of the furnace body, and the positions of the seed crystal and the growth mold were adjusted to ensure that both were perpendicular to the horizontal plane and that both, the crucible, and the temperature field were symmetrical about the same center.

[0045] (3) Crystal growth

[0046] Vacuum up to 10 -3The pressure was increased to 1 atmosphere by filling the crucible with high-purity inert argon gas. A medium-frequency induction heating crucible was used, with the power automatically increased at a rate of 500 W / h to melt the raw material. After the raw material was completely melted, the power was increased by 200 W and maintained at this constant power for 2 hours. Then, the power was reduced to the level at which the raw material melted, and this constant power was maintained for another 2 hours. The crucible was then slowly raised at a rate of 80 mm / h until the bottom of the growth mold contacted the melt interface. The crucible was then slowly raised at a rate of 10 mm / h, pausing for 10 minutes after every 2 mm increase, until the upper surface of the growth mold was completely immersed in the melt. The raising of the crucible was then stopped. The seed crystal was then slowly lowered at a rate of 100 mm / h until it contacted the melt, and the heating power was adjusted until the seed crystal made contact with the melt. After a stabilization time of 1 hour, the seed crystal is pulled at a rate of 3 mm / h, and automatic growth is started under the control of the weighing and equal diameter control system. The crucible rising rate u is determined by dividing the crystal growth weight rate g by the product of the crystal density ρ and the cross-sectional area s inside the crucible, i.e., u = g / (ρ*s). After the crystal grows to the required size, the automatic growth control is stopped, and the power is increased to 100W at a rate of 50W / h and kept constant for 2 hours. Then, the crystal is rapidly removed from the melt at a rate of 50 mm / h. After the crystal is removed, the power is reduced to 0W at a rate of 100W / h, resulting in a plate-shaped Nd:YLF crystal with a width of 52 mm, a thickness of 8 mm, and a length of 150 mm.

[0047] Example 3

[0048] The method for growing a tubular Nd:YAG crystal with an outer diameter of 59 mm, an inner diameter of 55 mm, and a length of 150 mm using the guided-mold method crystal growth apparatus provided in Example 1 includes the following steps:

[0049] (1) Temperature field installation and loading

[0050] According to the temperature field structure design, install the iridium crucible and the bottom insulation screen, side insulation screen, top insulation cover and other temperature field zirconia structural components in sequence. After installation, the temperature field structural components and crucible are horizontal and concentric with each other. Place the prepared columnar Nd:YAG polycrystalline growth raw material into the crucible.

[0051] (2) Growth mold and seed crystal installation

[0052] Nd:YAG crystal with

[111] crystal orientation is selected, and the lower end is cut into a vertical sheet with a width of 59mm, a height of 10mm and a thickness of 5mm as a seed crystal, and fixed on the seed crystal rod; the tubular crystal iridium growth mold is fixed on the top of the furnace body, and the positions of the seed crystal and the growth mold are adjusted to ensure that both are perpendicular to the horizontal plane, and both are symmetrical with the crucible and the temperature field at the same center.

[0053] (3) Crystal growth

[0054] Vacuum up to 10 -3The pressure was increased to 1 atmosphere by filling the crucible with high-purity inert nitrogen. A medium-frequency induction heating crucible was used, with the power automatically increased at a rate of 500 W / h to melt the raw material. After the raw material was completely melted, the power was increased by 200 W and maintained at this constant power for 5 hours. Then, the power was reduced to the level at which the raw material melted, and maintained at this constant power for another 2 hours. The crucible was then slowly raised at a rate of 50 mm / h until the growth mold contacted the melt interface. The crucible was then slowly raised at a rate of 20 mm / h until the upper surface of the growth mold was completely immersed in the melt. The raising of the crucible was then stopped. The seed crystal was then slowly lowered at a rate of 150 mm / h to contact the melt. The heating power was adjusted until the contact time between the seed crystal and the melt was stable for 2 hours. The seed crystal is pulled at a rate of 5 mm / h, and the automatic growth is started by the weighing and equal diameter control system. The crucible rising rate u is determined by dividing the crystal growth weight rate g by the product of the crystal density ρ and the cross-sectional area s inside the crucible, i.e., u = g / (ρ*s). After the crystal grows to the required size, the automatic growth control is stopped, and the power is increased to 200W at a rate of 100W / h and kept constant for 2h. Then, the crystal is rapidly removed from the melt at a rate of 300 mm / h. After the crystal is removed, the power is reduced to 0W at a rate of 200W / h, which yields a tubular Nd:YAG crystal with an outer diameter of 59mm, an inner diameter of 55mm, and a length of 150mm.

[0055] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A growth apparatus for growing large-volume crystals using a guided-mode method, characterized in that: Includes furnace body, crucible, growth mold and lifting system; A heat insulation plate is installed at the bottom of the furnace body, and the heat insulation plate has a round hole in the center for the transmission rod of the lifting system to pass through; a vertical through hole is provided at the top of the furnace body for the seed crystal rod to pass through the furnace body and connect to the lifting system and the weighing system; an air inlet is provided at the bottom of the furnace body and an air outlet is provided at the top. The crucible is cylindrical with an internal height greater than its internal diameter. It is used for heating and holding crystal growth raw materials. An induction coil and a heat preservation screen are arranged around the crucible. The growth mold is less than 20mm in height and is fixed to the top of the furnace. A crucible cover plate of the same material as the mold is fixed to the side of the mold. The lifting system comprises a transmission rod and a lifting drive motor. A heat-insulating support base plate is fixed to the upper part of the transmission rod, and a crucible is placed on the heat-insulating support base plate. The growth apparatus, through its low-height growth mold design and crucible elevation, ensures that the growth mold remains in constant contact with the melt during crystal growth, achieving continuous and full utilization of the melt raw material. With a fixed crucible diameter, increasing the crucible height increases the raw material capacity, reducing the amount of temperature field structure material and power consumption. During the loading process, lowering the crucible to the bottom of the growth mold reduces the space occupied by the growth mold, enabling one-time loading and saving crystal growth time and melt energy consumption.

2. The apparatus according to claim 1, characterized in that, Depending on the shape of the crystal being grown, the growth mold is designed as a plate or tube and is fixed to the top of the furnace body by a connecting rod. The upper surface of the growth mold is horizontal and flush with the upper surface of the induction coil. The growth mold is made of iridium, platinum, tungsten or molybdenum.

3. The apparatus according to claim 1, characterized in that, The transmission rod is a cylindrical corundum rod with a diameter of 20-50mm; the lifting motor is a servo motor with a positioning accuracy of less than 0.01mm, enabling stable lifting and lowering of the crucible.

4. The apparatus according to claim 1, characterized in that, The crucible is made of iridium, platinum, tungsten, or molybdenum; the heat insulation plate and the heat preservation screen are each independently selected from zirconium oxide, tungsten, molybdenum, or graphite.

5. The apparatus according to claim 1, characterized in that, The crystal growth apparatus for the guided model method also includes an automatic equal-diameter control system for weighing.

6. A method for growing large-volume crystals using the growth apparatus of claim 1, comprising the following steps: (1) Temperature field installation and loading According to the temperature field structure design, install the crucible and the bottom insulation screen, side insulation screen, and top insulation cover in sequence. After installation, the temperature field structure components and the crucible are horizontal and concentric with each other. Place the prepared crystal growth raw material into the crucible. (2) Installation of growth mold and seed crystal Based on the crystal to be grown, select an oriented seed crystal, cut it into shape according to the design, and fix it on the seed crystal rod; fix the growth mold on the top of the furnace body, adjust the position of the seed crystal and the growth mold to ensure that the seed crystal is vertical and perpendicular to the top end face of the growth mold, and that the seed crystal, the growth mold, the crucible, and the temperature field are symmetrical about the same center. (3) Crystal growth Vacuum up to 10 -3 Pa, fill with high-purity inert nitrogen or argon to 1 atmosphere, use medium-frequency induction heating crucible, automatically increase power at a rate of 100-1000W / h to melt the raw material. After the raw material is completely melted, continue to increase the power by 20-500W, maintain constant power for 1-10h, then reduce to the power at which the raw material melted, and continue to maintain constant power for 1-3h. The crystal growth is automatically controlled by the mold method, and the crucible rises at a rate calculated by the program during the automatic growth process.

7. The method according to claim 6, characterized in that, The raw material mentioned in step (1) is polycrystalline powder, which is pressed into a cake or column shape and placed in a crucible. When the raw material is placed in, the position of the crucible is adjusted in real time according to the temperature field structure and the height of the raw material, and the growth mold and cover plate are positioned above the crucible opening.

8. The method according to claim 6, characterized in that, The seed crystal in step (2) is designed and cut into square strips, vertical sheets or horizontal plates.

9. The method according to claim 6, characterized in that, In step (3), when growing crystals using the guided mold method, first raise the crucible at a rate of 5-100 mm / h until the bottom of the growth mold contacts the melt interface, then continue raising it at a rate of 5-50 mm / h, pausing for 10-30 minutes after each 1-2 mm increase, until the upper surface of the growth mold is completely immersed in the melt, then stop raising the crucible; proceed with seeding, slowly lowering the seed crystal at a rate of 10-300 mm / h until it contacts the melt, adjusting the power until the weight signal of the weighing system stabilizes, then begin automatic growth control; automatic growth control is performed by the upper weighing automatic equal diameter control system, and the crucible rising rate u is determined by dividing the crystal growth weight rate g by the product of the crystal density ρ and the cross-sectional area s inside the crucible, i.e., u = g / (ρ s), to achieve continuous material supply.

10. The method according to claim 6, characterized in that, In step (3), after the crystal grows to the required size, the automatic growth control is stopped, and the power is increased by 100-500W at a rate of 50-200W / h, and the power is kept constant for 1-2 hours. Then the crystal is removed from the melt at a rate of 50-600mm / h. After the crystal is removed, the power is reduced to 0W at a rate of 20-1000W / h, and a single crystal is obtained.

Images