Research on the Device and Method of Helium Recycling in Heat Exchange Method
The materials that can be used as LED substrates mainly include silicon,silicon carbide,sapphire,gallium nitride,etc.Due to poor lattice matching between silicon single crystal and gallium nitride,it cannot be commercially applied.The cost and price of silicon carbide single crystals are relatively high,and the current market price is about 5 times higher than that of sapphire crystals.The preparation of gallium nitride single crystals is more difficult.Although homogeneous epitaxy has the best quality,its price is hundreds of times higher than that of sapphire crystals.In summary,it is expected that sapphire single crystals will remain the ideal choice for LED substrate materials in the next 30 years.At present,the main growth methods for sapphire include Cz,EFG,Ky,and HEM.This article introduces various methods for sapphire crystal growth and analyzes their advantages and disadvantages.By analyzing the significant advantages of heat exchange method in growing large-sized defect free crystals and combining the principle of heat exchange method,a helium gas pipeline has been developed,providing a feasible device and method for reducing the cost of heat exchange method in growing sapphire.
sapphire growthheat exchange methodhelium gas recycling device
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