Sapphire Grow Method - Micro-Pulling And Shoulder Expanding at Cooled Center (SAPMAC)

Micro-pulling and shoulder expanding at cooled center is a sapphire growth method, which is also called micro-pulling rotation Kyropoulos. The is an improved method based on Kyropoulos Method and Pulling Method by Institute of Composite Structures from the Harbin Institute of Technology. It is used to grow large size crystal. Crystal growing system includes control system, vacuum system, heating body, cooling system and thermal protection systems. The following a picture, which is a schematic shoulder cold heart to put the system trace Czochralski method, SAPMAC grown single crystal, the outlook is usually pear-shaped, crystal diameter crucible can grow to more than the inner diameter of the small size of 10 ~ 30mm. The seed is processed into split shape, use seed clips at the bottom of the heat exchanger. Rotating and pulling the heat exchanger can be accomplished seed fixed, crystals, and the exchange interaction between the heat exchanger, crystal and melt.

Cold Heart put the shoulder when trace Czochralski growth of sapphire crystals, usually the entire crystal growth process can be divided into four control phases, namely seeding, put the shoulder, and other tracks, annealing and cooling phases. Seeding stage and put the shoulder is the use of adjusting heat exchanger cooling capacity, appropriate with a certain reduction in heating temperature (heating system can provide the crucible outer wall temperature) way to achieve the crystal and put the shoulder necking control. At this time the crystal growth rate and temperature gradient interface projecting large, which is conducive to the use of larger discharge shoulders, reducing the distance to put the shoulder to prevent flipping interface, while capable of dislocation within the seed crystal defects such as the original fast from Crystals spread to the crystal surface, effectively reducing defects within the crystal content. Large temperature gradient also can increase the interface crystal growth driving force, increase the stability of the interface. Until crystals grow to the desired diameter size (cold shoulder put heart trace Czochralski crystal diameter can grow from the inner wall of the crucible 1 ~ 3cm), crystals begin Equal grow into other tracks stage. With grown crystal size, heat exchanger efficiency of crystal growth decreases rapidly, so the crystal enters Once diameter growth stage, mainly by reducing the heating temperature(Crucible outer wall temperature of the heating system can provide) to achieve crystal growth.

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