Effect of various parameters on flow and temperature fields during CZ growth of oxide single crystals

Abstract

The Czochralski (CZ) technique is promising for the growth of high quality and large diameter bulk single crystals as electronic and opto-electronic materials. However, it is very difficult to find the optimum growth condition for the high quality and large diameter crystals because the CZ technique consists of complicated flow and thermal processes which are dominated by thermophysical properties. Therefore, it is required to understand the effect of the thermophysical properties on flow and temperature fields during crystal growth. The authors have previously observed flow patterns on LiNbO3, LiTaO3 and TiO2 melts, and discussed about the effect of Prandtl number on flow stability [1]. However, all properties including melting temperature and radiative parameters must be varied in this experiment [1]. In this study, the effect of thermophysical properties are investigated numerically because it is impossible to change an individual value of the thermophysical properties independently by experiments. Temperature coefficient of surface tension, viscosity, thermal conductivity of melt and emissivity of crystal was independently varied to investigate the individual effect of these thermophysical properties on crystal radius and melt/crystal interface shape. Moreover, the effect of crucible rotation, which rarely introduced to oxide single crystal growth, on the crystal radius and melt crystal interface shape is shown.