Segregation and interface shape control during EDG growth of CZT crystals

Computational models are applied to analyze the segregation of zinc and the shape of the solid-liquid interface during the growth of Cadmium Zinc Telluride (CZT) via an electrodynamic gradient freeze (EDG) process. Validation of the computational model is presented via a comparison between predicted and experimentally measured zinc distributions. Analysis of a large-scale CZT EDG growth system, previously analyzed by Gasperino et al. (JCG 311, 2327-2335, 2009), shows anomalous zinc segregation that features anomalous, non-monotonic axial concentrations and several local minima and maxima radially across the boule. A mechanistic explanation is put forth for this effect based on the evolution of multi-cellular melt flow structures, a particularly common feature of CZT growth. Optimized EDG furnace profiles are presented that promote the growth of CZT crystals with a uniformly convex interface shape. Such interface shapes are expected to improve the single-crystalline yield of this material.

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