Optimization of Crucible Descending Rate during the Crystal Growth of CdZnTe by a Vertical Bridgman Method

During the crystal growth by VBM, the relationships between crucible descending rate and crystal growth rate greatly influence the crystal quality. In this paper, finite element method (FEM) was used to simulate the growth process of CdZnTe crystal and the effects of different crucible descending rates on crystal growth rate and solid-liquid interface configuration were studied as well. Simulations show that when crucible descends at the rate of about 1mm/h, which nearly equals to crystal growth rate, nearly flat solid/liquid interface and little variation of axial temperature gradient near it can be attained, which are well consistent with the results of experiments. Therefore, CdZnTe crystal with low dislocation density can be obtained by employing and adjusting appropriate crucible moving rate during the crystal growth.