狭缝宽度及坩埚半径对分离结晶法制备CdZnTe晶体的影响

Effect of the gap width and crucible radius on CdZnTe crystal growth by detached solidification

借助有限元法,在常重力条件下对分离结晶过程进行全局数值模拟,研究了狭缝宽度及坩埚半径对CdZnTe晶体生长过程中整体传热与流动特性的影响。模拟结果表明系统内传热特性、熔体流型与狭缝宽度及坩埚半径密切相关:(1)狭缝宽度对分离结晶有决定性的作用,当狭缝宽度较小时,气-液弯界面两端的温差很小,导致增大晶体重新粘附于坩埚壁面的风险;随着狭缝宽度的增大,流动不稳定性增加,很难保持稳定的气-液弯界面形状,增加了实现晶体稳定生长的难度;(2)随着坩埚半径增大,Marangoni对流对熔体流动影响逐渐增大,结晶界面附近的熔体流动不稳定性增加,这不利于晶体的稳定生长。

In order to understand the effect of gap width and crucible radius on the characteristics of heat transfer and melt flow for the CdZnTe crystal growth, a set of global analyses for detached solidification was carried out using the finite-element method under the gravity condition. The simulation results show that the characteristics of heat transfer and melt flow pattern are strongly dependent on the gap width and crucible radius： （1） the gap width plays a decisive role in detached solidification. When the gap width was narrow, the temperature difference on two ends of meniscus was very small, which leads to increase the risk of crystal to reattach cruci ble wall. Along with the increasing gap width, the instability of melt flow intensifies, which consequently increases the difficult of keeping the stable of meniscus shape and crystal growth; （2） with the increase of crucible radius, the effect of Marangoni convention in the melt flow was gradually strengthened as well as the instability of melt flow nearby the solid-melt interface intensifies, which was adverse to the stable crystal growth.