阅读说明：本技术 一种锑化铟单晶的制备方法及其装置 (Preparation method and device of indium antimonide single crystal ) 是由 黄幸慰 朱刘 狄聚青 易明辉 刘运连 何志达 尹士平 熊威 于 2020-06-12 设计创作，主要内容包括：本发明提供了一种锑化铟单晶的制备方法及其装置,涉及晶体的制备领域。本发明将锑化铟籽晶、锑化铟多晶以及三氧化二硼加入密闭容器中,再采用垂直布里奇曼法(VB法)进行晶体生长,制得锑化铟单晶,这样,晶体从熔体的底部开始生长,不会受到浮渣的干扰,且通过控制加热程序可实现晶体生长的自动化,相比Cz法,对拉晶工人工艺经验要求低,成品成功率高、位错密度低、质量稳定可控；通过在密闭容器的上方设置单独控温的加热区,能产生保温的效果,使物料能更准确地达到设定的温度,使所得晶体整体质量分布更均匀。(The invention provides a preparation method and a device of an indium antimonide single crystal, and relates to the field of crystal preparation. The indium antimonide seed crystal, the indium antimonide polycrystal and the boron trioxide are added into the closed container, and then the vertical Bridgman method (VB method) is adopted for crystal growth to prepare the indium antimonide single crystal, so that the crystal grows from the bottom of the melt without being interfered by scum, the automation of crystal growth can be realized by controlling a heating program, compared with the Cz method, the method has the advantages of low requirements on the process experience of crystal pulling workers, high success rate of finished products, low dislocation density and stable and controllable quality; the heating zone with independent temperature control is arranged above the closed container, so that the heat preservation effect can be generated, the material can reach the set temperature more accurately, and the overall mass distribution of the obtained crystals is more uniform.)

1. A preparation method of an indium antimonide single crystal is characterized by comprising the following steps: adding the raw materials into a closed container, and then adopting a vertical Bridgman method to carry out crystal growth to obtain the indium antimonide single crystal; and during crystal growth, a heating zone for controlling temperature independently is arranged above the closed container, and the raw materials comprise indium antimonide seed crystals, indium antimonide polycrystal and boron trioxide.

2. The production method according to claim 1, wherein the indium antimonide polycrystal comprises a first indium antimonide polycrystal and a second indium antimonide polycrystal, and the indium antimonide seed crystal, the first indium antimonide polycrystal, the diboron trioxide and the second indium antimonide polycrystal are added to the closed container in this order.

3. The method according to claim 2, wherein the first indium antimonide polycrystal forms a first indium antimonide polycrystal layer after being added into the closed container, the first indium antimonide polycrystal layer has holes inside, and the diboron trioxide is added into the holes.

4. The production method according to any one of claims 1 to 3, wherein the raw materials are completely melted to obtain an indium antimonide seed crystal melt, an indium antimonide polycrystalline melt and a diboron trioxide melt, and the indium antimonide seed crystal melt, the indium antimonide polycrystalline melt and the diboron trioxide melt are sequentially solidified during the crystal growth.

5. The method as claimed in claim 4, wherein during the crystal growth, the raw material is first melted at a constant temperature of 480-600 ℃ and a total vertical temperature difference of 80-120 ℃, and then cooled to solidify or cooled to completely melt the raw material and solidify.

6. The method for preparing the crystal seed according to claim 5, wherein the closed container comprises a seed crystal cavity, a shoulder and a body with a constant diameter; and during the crystal growth, heating by adopting a heater surrounding the closed container, cooling to 460-525 ℃ at the speed of 0.2-2.0 ℃/h by the heater during the cooling, moving the heater upwards relative to the closed container at the same time of cooling, wherein the moving speed per hour is 0.0021-0.0066 time of the sum of the heights of the main body, the shoulder and the seed crystal cavity, stopping the relative movement after the cooling is finished, and keeping the temperature for 150-240h to obtain the indium antimonide single crystal.

7. The method as claimed in claim 5, wherein the heater comprises a first temperature zone, a second temperature zone, a third temperature zone, a fourth temperature zone and a fifth temperature zone which are sequentially distributed from top to bottom and independently controlled in temperature, wherein the first temperature zone is located above the sealed container, and the height ratio of the first temperature zone, the second temperature zone, the third temperature zone, the fourth temperature zone, the fifth temperature zone, the main body, the shoulder and the seed crystal chamber is 140-.

8. The manufacturing method according to claim 7, wherein a boundary line between the third temperature zone and the fourth temperature zone is at the same level as a boundary line between the body and the shoulder when performing the constant temperature melting.

9. The method as claimed in claim 8, wherein during the crystal growth, the temperatures of the first and second temperature regions are controlled to 560-.

10. An apparatus for carrying out the process according to any one of claims 1 to 9, wherein the apparatus comprises a sealing means and a heater, wherein the heater surrounds the closed vessel, and a portion of the heater higher than the closed vessel has a separate temperature control element.

Technical Field

The invention relates to the field of preparation of crystals, in particular to a method and a device for preparing indium antimonide single crystals.

Background

Indium antimonide (InSb) is a material with the narrowest forbidden band width and the largest mobility in a III-V group compound semiconductor, has very high quantum efficiency in a wave band of 3-5 mu m, and is widely applied to the aspects of infrared detectors, Hall devices and the like. In order to adapt to the trend of large-scale development of indium antimonide infrared focal plane array devices, large-size and low-dislocation indium antimonide single crystals attract more and more attention.

The current major growth method for indium antimonide single crystals is the Czochralski (Cz-claus-based) method, also known as the Cz method. The growth process of the Cz method is that under the protection of high-purity gas, raw materials are put in a crucible to be heated and melted, and after a seed crystal is inserted into a melt through a lifting rod, the seed crystal is slowly lifted, and a new crystal is obtained at the lower end of the seed crystal. However, the method has the disadvantages of high equipment cost, large crystal stress, high dislocation density and complex crystal growth process, and is not beneficial to growing large-size and low-dislocation single crystals. In the method for growing the indium antimonide single crystal disclosed in the patent (CN 109280978A), flowing high-purity hydrogen needs to be adopted for protection in the crystal growth process, so that the hidden danger of hydrogen leakage exists, an explosion-proof single crystal furnace needs to be designed, and the equipment cost is high; and the single crystal is grown through the processes of seeding, necking, shouldering, constant diameter, ending and the like, and twin crystal is easy to form; in addition, the method has strict requirements on the shouldering angle and has extremely high requirements on the process experience of crystal pulling workers.

Disclosure of Invention

In order to overcome the above disadvantages and shortcomings of the prior art, the present invention provides a method for preparing an indium antimonide single crystal and an apparatus thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

in a first aspect, the present invention provides a method for preparing an indium antimonide single crystal, comprising the steps of: adding the raw materials into a closed container, and performing crystal growth by adopting a VB (vertical Bridgman) method to obtain the indium antimonide single crystal; and during crystal growth, a heating zone for controlling temperature independently is arranged above the closed container, and the raw materials comprise indium antimonide seed crystals, indium antimonide polycrystal and boron trioxide.

Compared with the CZ method, the method has the advantages that the requirements for the experience of crystal pulling workers are low, the success rate of finished products is high, the dislocation density is low, and the quality is stable and controllable; according to the preparation method, the heating zone with independent temperature control is arranged above the closed container, so that the heat preservation effect can be generated, the materials can reach the set temperature more accurately, particularly the materials close to the heating zone, the overall mass distribution of the obtained crystal is more uniform, the average dislocation density is lower, and the difference between the carrier concentration and the electron mobility of the head part and the tail part is smaller. In addition, the preparation method adopts a seed crystal method to grow the indium antimonide single crystal, compared with a crystal grown without seed crystal (optional crystal), the dislocation density of the prepared indium antimonide single crystal can be reduced by several orders of magnitude, and the single crystal crystallization rate is obviously improved.

As a preferred embodiment of the preparation method, the indium antimonide seed crystal is added into the closed container, and then the indium antimonide polycrystal and the boron trioxide are added into the closed container.

As a preferred embodiment of the preparation method of the present invention, the indium antimonide polycrystal comprises a first indium antimonide polycrystal and a second indium antimonide polycrystal, and the indium antimonide seed crystal, the first indium antimonide polycrystal, the diboron trioxide and the second indium antimonide polycrystal are sequentially added to the closed container. According to the preparation method, when crystals grow, the indium antimonide polycrystal is covered by the diboron trioxide to prevent the polycrystalline material from being oxidized, the protection of hydrogen atmosphere is not needed, the hydrogen explosion risk is avoided, the equipment cost is reduced, meanwhile, the diboron trioxide is easy to absorb water, the closed container is sealed by adopting oxyhydrogen flame welding, water is generated in the process, and compared with the feeding sequence of the indium antimonide seed crystal, the indium antimonide polycrystal and the diboron trioxide, the feeding sequence of the indium antimonide seed crystal, the indium antimonide polycrystal, the diboron trioxide and the second indium antimonide polycrystal is adopted, the phenomenon that the diboron trioxide absorbs water to influence the effect of the sealed container when the sealed container is sealed can be prevented.

As a preferred embodiment of the preparation method of the present invention, the first indium antimonide polycrystal is added into the closed container to form a first indium antimonide polycrystal layer, the first indium antimonide polycrystal layer has holes inside, and the diboron trioxide is added into the holes. Thus, the indium antimonide polycrystal creates a relatively closed environment for the boron trioxide, and the contact area between the boron trioxide and the surrounding environment is reduced, so that the water absorption of the boron trioxide from the surrounding environment is reduced.

As a preferred embodiment of the preparation method of the present invention, during the crystal growth, the raw materials are completely melted to obtain an indium antimonide seed crystal melt, an indium antimonide polycrystalline melt and a boron trioxide melt, and then the indium antimonide seed crystal melt, the indium antimonide polycrystalline melt and the boron trioxide melt are sequentially solidified. The indium antimonide crystal starts to grow after all raw materials are melted, so that the disturbance of heat absorption of melting of the raw materials on a crystal growth interface is avoided, and the defect of the crystal is favorably reduced; the boron trioxide melt is solidified at last, so that the indium antimonide is prevented from being oxidized in the crystal growth process.

As a preferred embodiment of the preparation method, during the crystal growth, the raw materials are firstly controlled to be melted at constant temperature of 480-600 ℃ and the total vertical temperature difference of 80-120 ℃, and then the raw materials are cooled and solidified or cooled to be completely melted and then solidified. The melting temperature of the general VB method is slightly higher than the melting point (such as 540 ℃) of the material, the preparation method adopts higher melting temperature (up to 560-.

In a preferred embodiment of the production method of the present invention, the closed vessel is in a vacuum state during the crystal growth. The crystal grows in a vacuum environment, and the water absorption of boron trioxide and the oxidation of indium antimonide are avoided.

As a preferred embodiment of the preparation method, the constant-temperature melting time is 1-12 h.

As a preferred embodiment of the preparation method, the closed container comprises a seed crystal cavity, a shoulder and a body with the same diameter; and during the crystal growth, heating by adopting a heater surrounding the closed container, cooling to 460-525 ℃ at the speed of 0.2-2.0 ℃/h by the heater during the cooling, moving the heater upwards relative to the closed container at the same time of cooling, wherein the moving speed per hour is 0.0021-0.0066 time of the sum of the heights of the main body, the shoulder and the seed crystal cavity, stopping the relative movement after the cooling is finished, and keeping the temperature for 150-240h to obtain the indium antimonide single crystal. By adopting the specific cooling and curing procedure, the uniformity of the overall impurity distribution of the product and the uniformity of the product quality are improved, so that the difference between the carrier concentration and the electron mobility at the head part and the tail part is smaller.

As a preferred embodiment of the preparation method of the present invention, the heater includes a first temperature zone, a second temperature zone, a third temperature zone, a fourth temperature zone and a fifth temperature zone which are sequentially distributed from top to bottom and independently controlled in temperature, wherein the first temperature zone is located above the sealed container, and the height ratio of the first temperature zone, the second temperature zone, the third temperature zone, the fourth temperature zone, the fifth temperature zone, the main body, the shoulder and the seed crystal cavity is the first temperature zone: a second temperature zone: a third temperature zone: a fourth temperature zone: a fifth temperature zone: a main body: shoulder part: the seed crystal cavity is 140, 220, 230, 160, 170, 130, 140, 170, 180, 350, 360, 50, 60. When the heights of the first temperature zone, the second temperature zone, the third temperature zone, the fourth temperature zone, the fifth temperature zone, the main body, the shoulder and the seed crystal cavity are in the specific proportion, the temperature gradient of the crystal growth temperature field is convenient to regulate and control, so that the crystal quality is improved, and the crystal yield is improved.

As a preferred embodiment of the manufacturing method of the present invention, when the constant temperature melting is performed, a boundary line between the third temperature zone and the fourth temperature zone is at the same level as a boundary line between the body and the shoulder. The temperature gradient of the shoulder and the main body can be favorably regulated and controlled, the crystal growth rate is controlled, the fifth temperature zone is positioned below the closed container when the fifth temperature zone is melted at constant temperature, and compared with the condition that the fifth temperature zone is not arranged, the fifth temperature zone is arranged to ensure the subsequent cooling solidification initial stage, and the material at the bottom of the closed container can more accurately reach the preset temperature, so that the crystal grown at the solidification initial stage has better quality, for example, the crystal forming rate of the single crystal is ensured to be higher.

As a preferred embodiment of the preparation method, during the crystal growth, the temperature of the first temperature zone and the second temperature zone is controlled to be 560-. Under the specific process condition, the crystallization rate of the indium antimonide single crystal is 100 percent, the uniformity of the whole quality of the product is further improved, and the average dislocation density is as low as 20/cm²Hereinafter, the difference in carrier concentration and electron mobility between the head portion and the tail portion is further reduced.

As a preferred embodiment of the preparation method of the invention, after the constant temperature is maintained for 150-240h, the heater is cooled to 20-50 ℃ at the speed of 5-15 ℃/h.

As a preferred embodiment of the preparation method of the present invention, the mass of the diboron trioxide is 0.2% -0.5% of the total mass of the first indium antimonide polycrystal and the second indium antimonide polycrystal.

As a preferred embodiment of the preparation method, the water content of the boron trioxide is within the range of 200-1000ppm, and the purity is more than 5N, so as to reduce the influence of water on the efficacy of the boron trioxide as much as possible.

As a preferable embodiment of the production method of the present invention, the first indium antimonide polycrystal and the second indium antimonide polycrystal have a carrier concentration of 1 × 10 or less under a 77K condition¹⁴cm^-3Electron mobility ≥ 5 × 10⁵/(V·s)。

In a second aspect, the invention also provides a device for implementing the preparation method, which comprises a sealing device and a heater, wherein the heater surrounds the closed container, and a part of the heater, which is higher than the closed container, is provided with a separate temperature control element.

The preparation device of the indium antimonide single crystal is an improved vertical Bridgman crystal growth device, the common vertical Bridgman crystal growth device is not provided with a heating zone above a sealing device, and the preparation device of the indium antimonide single crystal generates a heat preservation effect by arranging the independent heating zone above the sealing device, so that materials placed in a second crucible can reach a set temperature more accurately, particularly materials close to the heating zone, and therefore the obtained crystal is more uniform in mass distribution, lower in average dislocation density, and smaller in difference between the carrier concentration and the electron mobility at the head part and the tail part. Meanwhile, the preparation device of the indium antimonide single crystal can realize the automation of crystal growth by controlling a heating program, has low requirements on the technological experience of crystal pulling workers compared with a Cz method, has high success rate of finished products, low dislocation density and stable and controllable quality, and can not be interfered by scum when the crystal grows from the bottom of a melt.

As a preferred embodiment of the apparatus of the present invention, the sealing apparatus includes a first crucible, a second crucible, and a sealing cap, the upper end of the second crucible is open and is placed in the first crucible, the sealing cap is welded to the upper end of the first crucible, the heater surrounds the sealed container, and the first crucible and the second crucible each include, from bottom to top, a seed crystal cavity, a shoulder, and a body having an equal diameter.

As a preferred embodiment of the apparatus of the present invention, the heater includes a first temperature zone, a second temperature zone, a third temperature zone, a fourth temperature zone and a fifth temperature zone which are sequentially distributed from top to bottom and independently controlled in temperature, and the height ratio of the first temperature zone, the second temperature zone, the third temperature zone, the fourth temperature zone, the fifth temperature zone, the main body of the first crucible, the shoulder of the first crucible and the seed crystal cavity of the first crucible is the first temperature zone: a second temperature zone: a third temperature zone: a fourth temperature zone: a fifth temperature zone: main body of first crucible: shoulder of first crucible: the seed crystal cavity of the first crucible is 140, 150, 220, 230, 160, 170, 130, 140, 170, 180, 350, 360, 40, 50, 60. In this way, each part of the heater can independently control the temperature, thereby realizing vertical gradient heating. In addition, when the heights of the first temperature zone, the second temperature zone, the third temperature zone, the fourth temperature zone, the fifth temperature zone, the main body of the first crucible, the shoulder of the first crucible and the seed crystal cavity of the first crucible are in the specific proportion, the temperature gradient of the crystal growth temperature field is convenient to regulate and control, so that the crystal quality is improved, and the crystal yield is improved.

As a preferred embodiment of the apparatus of the present invention, the height ratio of the first temperature zone, the second temperature zone, the third temperature zone, the fourth temperature zone, the fifth temperature zone, the body of the first crucible, the shoulder of the first crucible, and the seed crystal cavity of the first crucible is the first temperature zone: a second temperature zone: a third temperature zone: a fourth temperature zone: a fifth temperature zone: main body of first crucible: shoulder of first crucible: the seed cavity of the first crucible was 149:224:168:138:178:350:50: 55. Especially, when the device is under the specific size, the temperature gradient of the crystal growth temperature field is more convenient to regulate and control.

In a preferred embodiment of the apparatus of the present invention, the upper and lower ends of the seed crystal cavity of the first crucible and the upper half of the shoulder of the first crucible are respectively provided with one or more temperature thermocouples. The melting position of the indium antimonide seed crystal can be monitored by arranging temperature thermocouples at the upper end and the lower end of the seed crystal cavity; the temperature thermocouple is arranged on the upper half part of the shoulder part, so that whether the material is molten or not can be monitored, and the process control is facilitated.

As a preferred embodiment of the device, the device further comprises a supporting device, wherein the supporting device is arranged below the first crucible and used for supporting and fixing the first crucible, so that the first crucible can be quickly and accurately placed at a preset position after the material is added.

As a preferred embodiment of the device of the present invention, the support device is provided with a through hole, and the temperature thermocouple is inserted into the through hole.

As a preferred embodiment of the apparatus of the present invention, the apparatus further comprises a controller which controls the heater to ascend or descend.

In a preferred embodiment of the apparatus of the present invention, the heater, the body of the first crucible, and the body of the second crucible are cylinders having the same center axis. Compared with other shapes, the three shapes are cylindrical, so that the material loaded in the second crucible can be uniformly heated.

In a further preferred embodiment of the apparatus of the present invention, the inner diameter of the heater is 10 to 100mm longer than the inner diameter of the main body of the first crucible, the wall thickness of the main body of the first crucible is 3 to 5mm, the inner diameter of the main body of the first crucible is 5 to 10mm longer than the inner diameter of the main body of the second crucible, and the wall thickness of the main body of the second crucible is 1 to 2 mm.

As a further preferred embodiment of the device of the present invention, the inner diameter of the heater is 155 mm; the inner diameter of the main body of the first crucible is 112mm, and the wall thickness is 5 mm; the inner diameter of the main body of the second crucible is 105mm, and the wall thickness is 2 mm.

When the inner diameter of the heater is 10-100mm longer than the inner diameter of the body of the first crucible, and the inner diameter of the body of the first crucible is 5-10mm longer than the inner diameter of the body of the second crucible, excellent heat radiation efficiency therebetween is obtained; when the wall thickness of the main body of the first crucible is 3-5mm, it has excellent mechanical strength and is not easily broken; after the second crucible is used each time, the second crucible is required to be cleaned, but the thickness of the second crucible is reduced by each cleaning, and when the wall thickness of the main body of the second crucible is 1-2mm, the second crucible has high mechanical strength and is convenient to recycle. The inner diameter of the heater is selected to be 155mm, the inner diameter of the main body of the first crucible is 112mm, the wall thickness is 5mm, the inner diameter of the main body of the second crucible is 105mm, and the wall thickness is 2mm, taking the radiation efficiency, the mechanical strength and the cleaning effect into comprehensive consideration.

In a preferred embodiment of the apparatus of the present invention, the shoulders of the first crucible and the second crucible are both tapered.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the VB method is adopted to prepare the indium antimonide single crystal, the crystal grows from the bottom of the melt and is not interfered by scum, the automation of crystal growth can be realized by controlling a heating program, compared with the Cz method, the method has low requirements on the process experience of crystal pulling workers, high success rate of finished products, low dislocation density and stable and controllable quality;

(2) when the indium antimonide single crystal is prepared, the preparation method does not need to be carried out in a hydrogen atmosphere, so that the risk of hydrogen explosion is avoided, and the equipment cost is reduced;

(3) the invention can generate heat preservation effect by arranging the heating zone with independent temperature control above the closed container, so that the material can reach the set temperature more accurately, the whole mass distribution of the obtained crystal is more uniform, the average dislocation density is lower, and the difference between the carrier concentration and the electron mobility at the head part and the tail part is smaller.

(4) The invention adopts the feeding sequence of indium antimonide seed crystal, indium antimonide polycrystal, boron trioxide and second indium antimonide polycrystal, thereby avoiding the absorption of water by the boron trioxide.

Drawings

FIG. 1 is a schematic view of an apparatus for producing an indium antimonide single crystal according to example 1;

FIG. 2 is a schematic view showing the structure of a closed vessel in an apparatus for producing an indium antimonide single crystal according to example 1;

the crucible comprises a first crucible, a second crucible, a sealing cap, a heater, a support device, a heater, a support device, an indium antimonide seed crystal, an indium antimonide polycrystal, a boron trioxide, a temperature thermocouple, a main body of the first crucible, a conical shoulder of the first crucible, a seed crystal cavity of the first crucible, a main body of the second crucible, a conical shoulder of the second crucible, a temperature thermocouple, a main body of the first crucible, a temperature thermocouple, a temperature control device and a temperature control device, wherein the temperature control device comprises 1-the first crucible, 2-the second crucible, 3-the.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to specific examples.