Journal of Crystal Growth, Vol.364, 133-144, 2013
The prospects for traveling magnetic fields to affect interface shape in the vertical gradient freeze growth of cadmium zinc telluride
The influence of a traveling magnetic field (TMF) on vertical gradient freeze (VGF) growth of cadmium zinc telluride (CZT) is studied using a coupled model of magnetic induction, fluid dynamics, and heat transfer. Simulations are performed to determine the influences of current, phase shift, and frequency on melt flow and growth interface shape. A downward traveling electromagnetic wave drives flow downward at the wall, which tends to flatten the interface, whereas an upward traveling wave has the opposite effect. An optimum phase shift that maximizes Lorentz force is found to depend only on system geometry. Large currents (similar to 300 A) and high frequencies (similar to 500 Hz) make a significant impact on interface shape in the absence of thermal buoyancy, but are ineffectual under realistic conditions in a 4 in.-diameter ampoule, for which buoyancy dominates Lorentz force throughout the melt. The results indicate that interface shape in this CZT growth system is strongly governed by furnace heat transfer and is difficult to modify by TMF-driven forced convection. (C) 2012 Elsevier B.V. All rights reserved.
Keywords:Computer simulation;Magnetic fields;Convection;Heat transfer;Gradient freeze technique;Semiconducting II-VI materials