低压布里奇曼法CdZnTe晶体生长及其热应力模拟  

Thermal Stress Simulation and CdZnTe Crystal Growth by Low Pressure Bridgman Method

作　　者：刘洪涛[1] 桑文斌[1] 袁铮[1] 闵嘉华[1] 詹峰[1] 

机构地区：[1]上海大学,上海200072

出　　处：《稀有金属材料与工程》2007年第6期1016-1019,共4页Rare Metal Materials and Engineering

基　　金：国家自然科学基金项目(10175040);上海市科委重大项目(03DZ11006);上海市教委基金(02AK30)资助

摘　　要：采用有限元方法,对晶体结晶结束位置处的晶体内部热应力分布进行了数值模拟,结果表明:晶体在石英安瓿内壁附近,变径处以及头部尖端处的热应力较大,应力值约在108N/m2数量级,晶体中部热应力分布较小且比较均匀,约为107N/m2。为了防止晶体在生长过程中头部尖端处以及变径处的位错延伸至晶体内部,提出了在不同生长阶段采用不同下降速度,并且在晶体下降至变径处采用“回熔”操作的新工艺。实验结果表明:利用新工艺生长的晶体位错密度明显降低,约为2×102cm-2,同时显著地提高了晶体的利用率。Finite elements method was used to numerically simulate the thermal stress distribution in CdZnTe Crystal at the site where the crystallization just finished. The simulation results showed that the thermal stresses near the quartz ampoule wall, in the part of changing-diameter and at the tip on the crystal were higher, with orders of about l0^8 N/m^2, but exhibited homogenous distribution in middle part of crystal, with orders of about 10^7 N/m^2. To prevent the dislocation in the part of changing-diameter and the tip end of the head part elongating into the middle part, a new kind of process was put forward by using different descent rates in the different stage of crystal growth and a melt-back process when the crystal descended down to the part of changing-diameter. The experimental results showed that the dislocation density in CdZnTe crystal grown by the new process decreased much to a very low level of 2×10^2 cm^-2, and the utilization ratio of cystal greatly increased if compared to the as-grown crystal by high press Bridgman method.

关 键 词：cdznTe晶体生长 热应力模拟 探测器 

分 类 号：TN304[电子电信—物理电子学]