半导体单晶生长过程中的位错研究

阐述了现有的半导体单晶位错模型,即临界切应力模型和粘塑性模型的基本理论及应用状况.分析了熔体法单晶生长过程中影响位错产生、增殖的各种因素,以及抑制位错增殖的措施.与熔体不润湿、与晶体热膨胀系数相近的坩埚材料,低位错密度的籽晶可有效地抑制生长晶体的位错密度;固液界面的形状及晶体内的温度梯度是降低位错密度的关键控制因素,而两因素又受到炉膛温度梯度、长晶速率、气体和熔体对流等晶体生长工艺参数的影响.最后,对熔体单晶生长过程的位错研究进行了展望.

Study on Dislocation in Growing Process of Semiconductor Single Crystals

The basic theories and the applications of both the critical resolved shear stress model and visco-plastic model are presented for predicting the dislocation density during crystal growth process.The factors which affect the generation and multiplication of dislocation are summarized and analyzed.The crucible which is not wetted by the melt,or has the similar thermal expansion coefficient to the crystal,and the seed with lower dislocation density could reduce the dislocation density of grown crystals efficiently.The furnace temperature gradient,crystal growth rate,melt convection and the gas convection above the melt seriously influence the shape of solid-liquid interface and the temperature gradient in the crystal,both of which are the most important influence factors affecting the dislocation density.At last,the prospects for the study of dislocation density in the growing crystals are given.