On the effects of furnace gradients on interface shape during the growth of cadmium zinc telluride in EDG furnaces

Numerical simulations are performed to assess cadmium zinc telluride (CZT) interface shape dependency on thermal gradients in electrodynamic gradient (EDG) furnaces. Results explain how larger furnace gradients in these systems tend to flatten the shape of the solid-liquid interface. Convection dominates heat transfer through the melt, and mixing acts to radially homogenize the melt temperature field. These features do not significantly change with gradient conditions. In contrast, changing the rate of heat conduction through the solid, notably via changes to the furnace profile adjacent to the crystal, have an overriding influence on the interface shape. Increased gradients increase the ability for latent heat to be transported axially through the crystal and flatten the interface; however, the sensitivity of the shape of the interface to details of the furnace heating profile decreases as overall gradients increase. The engineering of the interface shape in these systems via subtle control of the furnace should be possible, but rational design changes will require the insight obtained from predictive models.