A transient, coupled model has been developed to analyze the segregation of zinc in cadmium zinc telluride (CZT) grown in an electrodynamic gradient freeze (EDG) furnace. The coupled model consists of a local model that solves for time-dependent melt flow, heat transfer, meltcrystal interface position, and zinc distribution in both melt and solid phases and a quasi-steady-state global model that features realistic furnace heat transfer. After verification and validation tests, the model is applied to predict composition patterns in a large-scale CZT EDG growth system previously analyzed by Gasperino et al. [On crucible effects during the growth of cadmium zinc telluride in an electrodynamic gradient freeze furnace, J. Crys. Growth 311 (2009) 23272335]. Surprisingly, anomalous zinc segregation is predicted, featuring a non-monotonic axial concentration profile and several local minima and maxima across the boule. A mechanistic explanation is put forth based on the cumulative effect of changes in multi-cellular melt flow structures, a particularly susceptible occurrence for CZT systems. Additional effects of furnace translation rate and solid state diffusion are probed.
Bibliographical noteFunding Information:
The work conducted at the University of Minnesota was supported in part by the Department of Energy, National Nuclear Security Administration , under Awards DE-FG52-06NA27498 and DE-FG52-08NA28768 . Fisk University researchers acknowledge the support of Department of Homeland Security Award 2010-DN-077-ARI041-02 . The content of the work does not necessarily reflect the position or policy of the United States Government, and no official endorsement should be inferred. Computational resources were provided by the Minnesota Supercomputer Institute. Significant technical contributions were also provided by K.A. Jones at WSU in the CZT growth experiment.
- A1. Computer simulation
- A1. Convection
- A1. Heat transfer
- A1. Segregation
- A2. Bridgman technique
- B2. Semiconducting IIVI materials