Study on the Pulling Speed Influence for Growth of Sapphire Single Crystal

• Main Authors: Huang, Chong-Hao, 黃重浩
• Other Authors: Wu, Yu-Shiang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/84573571297160486081

碩士 === 中華科技大學 === 機電光工程研究所碩士班 === 100 === This study used Kyropoulos method for the growth of sapphire single crystal, to explore the influence of pulling speed to the sapphire quality during the growing process. In setting faster pulling rates for crystal growth parameters, firstly we did 0.5 mm/hr for 24 consecutive hours, then 0.3 mm/hr for 15 consecutive hours, and lastly 0.1 mm/hr for 90 consecutive hours to the end of the process. In setting the slower rates, we did 0.3 mm/hr for 65 consecutive hours, then 0.1 mm/hr for 93 consecutive hours to the end of the process. The two crystals were compared by the appearance and clarity, and were observed for the internal impurities, bubbles and other macroscopic defects under strong light. Due to the insufficient time in early growing stage which resulted in excessive crystal body growth, cone-shaped crystal shape, and pot-sticking situation, the result suggests that the crystal grew under faster pulling rate appeared three major defects: firstly, the cracks were made at the pot-sticking areas when leaving the crucible; secondly, large areas of cracks appeared since the crystal body was too close to crucible so that the crystal temperature dropped too fast; last, there were a large amount of impurities attached to the bottom of the crystal and made it unqualified for the commercialization. On the other hand, due to the slow and long-term growing time during the early- and mid-growing stage, the crystal grew under slower pulling rate presented an obvious cylindrical shape, no pot-sticking situation due to excessive growth, transparent and qualified for the commercial specifications.