导模法生长蓝宝石晶体的退火工艺

采用导模法生长了片状蓝宝石单晶。由于石墨发热体的高温挥发，使晶体尾部产生黑色絮状包裹体，晶体内部生成色心。为了消除片状蓝宝石晶体内的包裹体和色心，在不同气氛下对生长的晶体样品进行了退火处理。退火实验表明，含有包裹体的尾部样品在1500℃空气中退火20h并以50℃／h的速率降温，可消除晶体内的碳包裹体，晶体变为无色、透明。在氢气中1600℃退火37h后，F色心引起的205mm的吸收峰和Fe^3＋所引起的200～230的吸收峰均被消除。表明高温氢气中退火是消除导模法生长蓝宝石晶体内部F色心和Fe^3＋吸收的最佳退火方法。

Annealing Process of Sapphire Crystal Grown by Edge Defined Film Fed Growth Method

Sapphire single crystal ribbon was grown via an edge defined film fed growth(EFG) method.The carbon volatilization in a graphite heater at high temperatures results in some black inclusions in tail crystal and color center in the crystal.In order to eliminate black inclusions and color center in the crystal,the sapphire crystal grown was annealed by different annealing processes.The black inclusions in tail crystal disappear and the crystal became colorless and transparent after annealing in air at a cooling velocity of 50 ℃/h and 1 500 ℃ for 20 h.For the crystal sample after annealing in H2 at 1 600 ℃ for 37 h,the absorption peak at 205 nm caused by F color center and the absorption shoulder at 200–230 nm caused by Fe3+ is disappeared.The results indicate that high temperature hydrogen annealing is a promising annealing method to eliminate the F color center and the absorption shoulder at 200–230 nm caused by the Fe3+ in the sapphire crystal grown by EFG method.