垂直布里奇曼法CdZnTe晶体生长过程的数值分析

Numerical modeling of CdZnTe-VBM crystal growth

模拟计算了半导体材料CdZnTe布里奇曼法单晶体生长过程,分析了熔体的过热温度、坩埚侧面强化换热以及坩埚加速旋转(ACRT)等因素对结晶界面的形态和晶体组分偏析的影响,结果表明:当熔体的过热温度减小时,熔体中自然对流的强度显著降低,固液界面的凹陷深度有所增加,晶体的轴向等浓度区显著加长,而晶体组分的径向偏析明显增大.坩埚的侧面强化换热增加了自然对流强度,也增大了固液界面的凹陷,但是对溶质成分的偏析影响较小.坩埚加速旋转引起的强迫对流强度远大于自然对流,显著增大了固液界面的凹陷,使熔体中的溶质分布成为均一的浓度场,显著减小了晶体组分的径向偏析,增加了晶体组分的轴向偏析.

A numerical simulation study was carried out for CdZnTe vertical Bridgman method (VBM) crystal growth. Effects of the melt super-heat temperature, the reinforcement of the crucible lateral heat radiation, and accelerated crucible rotation technique (ACRT) on the melt convection, the solid-liquid interface concavity and solute segregation of the crystal.were investigated. When the super-heat temperature of the melt is reduced, the melt convection becomes weak obviously, the axial iso-concentration zone of the crystal increases greatly, and the radial segregation increases a lot. The reinforcement of the crucible lateral heat radiation results in the enhancement of the convection, increases the concavity of the solid-liquid interface a little, but hardly affect the solute segregation of the crystal. The forced convection induced by ACRT is much more powerful than the natural convection. It greatly increases the concavity of the solid-liquid interface and the axial segregation of the crystal, while decreases the radial one extraordinarily. The radial solute segregation of the crystal with ACRT is near to zero.