VGF法生长6英寸Ge单晶中热应力的数值模拟优化  

Thermal Stress Optimization in 6 Inch VGF Growth of Ge Crystal by Numerical Simulation

作　　者：丁国强[1] 苏小平[1] 张峰燚[1] 黎建明[1] 冯德伸[1] 

机构地区：[1]北京有色金属研究总院,北京国晶辉红外光学科技公司,北京100088

出　　处：《稀有金属》2011年第2期244-248,共5页Chinese Journal of Rare Metals

基　　金：国家“863”高技术研究项目(2002AAF3102)资助

摘　　要：VGF技术生长单晶时温度梯度较低,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。采用数值模拟研究了VGF法6英寸低位错Ge单晶的生长,结果表明在采用自主研发的VGF炉生长6英寸Ge单晶时,晶体生长过程中晶体与熔体中均具有较低的温度梯度(这里的温度梯度是指的界面附近的温度梯度),尤其当晶体生长进入等径生长阶段后,晶体中的轴向温度梯度在2～3 K.cm-1之间,熔体中的轴向温度梯度0.8～1.0 K.cm-1之间;晶体中的热应力除边缘外均在(2～9)×104 Pa之间,低于Ge单晶的临剪切应力,且晶体生长界面较平整;坩埚与坩埚托之间的间隙对于晶体生长中的"边界效应"影响显著,将8 mm间隙减小至2 mm后,埚壁外侧的径向热流增加,使得晶体边缘的最大热应力减小至0.21 MPa和Ge单晶的临剪切应力相当,实现了热场的优化。As lower temperature gradient and lesser crystal growth rate could be realized in the crystal grown by VGF technique,VGF was one of the main process for large-size and high quality crystal growing.Ge crystal of 6 inch growing with VGF process was studied by numerical simulation,and the module based on the VGF crystal growing furnace designed by GRINM（General Research Institute for Non-Ferrous Metals of Beijing）.The result showed that the temperature gradient（approach the interface） in crystal and melt was lower.Particularly,when the crystal was grown at full-grown segment,the axial temperature gradient was between 2~3 K·cm-1 in the crystal and 0.8~1 K·cm-1 in the melt.The thermal stress was between（2~9）×104 Pa,lower CRSS（Critical Resolved Shear Stress） of Ge crystal except that at the edge of crystal.At the same time,the interface kept a flatness shape.The gap between the crucible and the support had a great affect on the ＂interface effect＂.The heat flux vertical the wall of the p-BN crucible was increased by reducing the width of the gap from 8 mm to 2 mm,which led the maximum thermal stress at the edge of crystal to reduce to 0.21 MPa.The value was equivalent to the CRSS of Ge crystal,and the thermal field had been optimized.

关 键 词：锗单晶 垂直梯度凝固 数值模拟 

分 类 号：O614.43[理学—无机化学]