用VGF法生长6英寸锗单晶中籽晶熔接工艺研究

采用垂直梯度凝固(VGF)法生长单晶时,其温度梯度较低,生长速率较小,目前已成为生长大直径、低位错密度晶体的主流技术之一.在VGF法生长单晶的过程中,籽晶的熔接工艺直接影响着单晶生长的成败.研究了拉速器速度、保温时间及石英棉用量对6英寸(1英寸=2.54 cm)锗单晶VGF生长中籽晶熔接的影响,并确定了最佳的籽晶熔接工艺.研究结果发现,当拉速器速度为3～4 mm/h、保温时间为75～100 min、石英棉用量为15～20 9时,实现了对籽晶熔接工艺的精准控制,熔接长度为12～22 mm,位错密度小于500 cm-2,有效地降低了生产成本,提高了生产效率和单晶率.

Research on Seed Crystal Welding Process of 6-inch Ge Single Crystal by Vertical Gradient Freeze Method

When the single crystal is grown by vertical gradient freeze (VGF) method,the temperature gradient is lower and the growth rate is lesser.At present the VGF method has become one of the mainstream technologies for the growth of large diameter and low dislocation density crystals.During the process of growing single crystals by VGF method,the welding process of the seed crystal directly affects the success or failure of single crystal growth.The effects of the speed of lifting platform,the holding time and the dosage of silica wool on the seed crystal welding during VGF growth of the 6-inch (1 inch =2.54 cm) Ge single crystal were studied.And the best seed crystal welding process was determined.The research results show that when the speed of lifting platform is 3-4 mm/h,the holding time is 75-100 min and the dosage of silica wool is 15-20 g,the precise control of the seed crystal welding process is realized.The welding length is about 12-22 mm and the dislocation density is less than 500 cm-2.The production cost is effectively reduced,and the production efficiency and the rate of single crystal are improved.