Global Simulation Crystal Growth Of CdZnTe By The Detached Vertical Bridgman Method

A computational model was developed to study the crystal growth of CdZnTe by detached vertical Bridgman method. The thermal and flow characteristics are established and analyzed. Then, temperature distribution of crystal growth system, stream function distribution and the solid-liquid interface were calculated by the CFD software-FLUENT in various working conditions. The rules by changing gap width (e), crucible radius (ro), temperature gradient are presented.Results show that, under microgravity condition, with the increase of gap width (e), when the upper melt is non-slip wall condition, the max stream functions show the similar trend. However, when upper melt is free surface, the rules are opposite. At the same time, for the same e, the max stream function of the"free surface condition"is larger than the"non-slip wall one". For the non-slip wall condition in the upper melt, the max stream function appears nearby the meniscus. When it comes to the free surface in the upper melt condition, max stream function appears at the upper melt which is nearby the gas-melt interface. Then, with the increase of temperature gradient, flow of the crystal growth system is stronger too. Because the cold zone temperature of crystal growth system is decreased, it makes the solid-liquid interface rising.Under gravity condition, the effect of gravity is strengthened with increasing crucible radius (ro), which makes the max stream function larger. Comparing with the microgravity condition, due to appearing buoyancy convection, the flow characteristic in gravity flow is more complex. The max stream function appears at the center of flow cell at the upper melt which is driven by buoyancy– thermal capillary forces. At the same time, the position of flow cell center is climbing up when increasing ro. In addition, based on the velocity and temperature distribution on the meniscus and upper free surface, it can be found the similar rules in all sorts of radius in gravity and the maximum velocity value occurs in ro = 16mm.