声光晶体TeO2的生长及缺陷研究

本文研究了直接ＴeO２晶体中的主要晶体缺陷形成机理，讨论分析了Ｔ eO2单晶生长的工艺参数对晶体缺陷的影响，结果表明：晶体裂缝的主要与温度梯度有关，温度梯度大于２０－２５℃/cm及出现界面翻转时，易造成晶全的开裂，位错密度增加，晶体中的包裹体主要为气态包裹全，它的形成主要与籽晶的转速和晶体的提拉速率有关，转速１５－１８r/min，拉速０.55mm/h，固液界面微凹，可以减少晶体中的气态包裹体，晶体台阶由晶体生长过程中温度和生长速度的引起伏引起，当台阶间距较宽时，易形成包裹体。

Study on Czochralski Growth of TeO2 Single Crystal and Defects

The formation mechanism of main defects in TeO2 single crystals grown by Czochralski technique and the effects of growth parameters on defects have been studied in this paper.The results showed that the cracking in TeO2 single crystal is mainly related to the temperature gradient.To avoid the crystal being cracked and to decrease the dislocation density,the crystal can be grown under temperature gradient of 20-25℃/cm.And the incorporation of gas inclusions into the crystal is due to the pulling rate and the seed rotation rate.The crystal without bubbles can be obtained when a rotation rate of 15-18r/min and a pulling rate of 0.55mm/h are employed,which can lead a concave solid-liquid interface.The reason for growth steps in crystal can be explained by the instability of temperature and growth speed during growth process.