Three-dimensional imperfections in a model vertical Bridgman growth system for cadmium zinc telluride

Three-dimensional, quasi-steady-state modeling of heat transfer, flow, and segregation are carried out with a self-consistent, parallel, finite element model to analyze the effects of imperfections on a model system for the vertical Bridgman growth of cadmium zinc telluride. Even small amounts of ampoule tilting (defined as the offset between the ampoule axis from the direction of gravity) produce large asymmetries in the flow and solute segregation. However, the application of ampoule rotation, at rates far smaller than considered in prior studies, acts to restore axisymmetric segregation behavior. Thermal imperfections caused by ampoule offset in the furnace bore and ampoule distortion are also shown to yield significant three-dimensional flows and segregation asymmetry. Local heating is shown to strongly affect solute mixing and may be effective in active strategies for segregation control. (C) 2003 Elsevier B.V. All rights reserved.