Numerical analysis on Hg_1-xCd_xTe growth by ACRT-VBM

The ACRT-VBM growth process of Hg_1-xCd_xTe crystal has been numerically analyzed by the finite difference method. The forced convection resulting from the accelerated crucible rotation technique (ACRT) and its effects on the position and the shape of the melt/crystal interface are studied, and the solute redistribution and radial segregation are evaluated. The results show that during ACRT process the convection vortex in the melt appears, develops, declines and disappears periodically according to the periodic change of the crucible rotations. Corresponding to the periodic change of the flow field, the growth rate, the temperature and concentration oscillate periodically. When ACRT with certain crucible rotation sequence is applied to the Bridgman crystal growth process of Hg_1-xCd_xTe, the interface depth decreases markedly as the results of the solute transport effect of ACRT flow. The proper crucible rotation sequence is `the discontinuous triangle wave' consisting of the acceleration, deceleration and rest periods. For the Hg_1-xCd_xTe crystal with a radius of 0.60 cm, the period (T_ACRT) of 36 s and the maximum rotation rate (ω-max$/) about 45 rpm are preferable.