We employ finite-element modeling to assess the effects of the accelerated crucible rotation technique (ACRT) on cadmium zinc telluride (CZT) crystals grown from a gradient freeze system. Via consideration of tellurium segregation and transport, we show, for the first time, that steady growth from a tellurium-rich melt produces persistent undercooling in front of the growth interface, likely leading to morphological instability. The application of ACRT rearranges melt flows and tellurium transport but, in contrast to conventional wisdom, does not altogether eliminate undercooling of the melt. Rather, a much more complicated picture arises, where spatio-temporal realignment of undercooled melt may act to locally suppress instability. A better understanding of these mechanisms and quantification of their overall effects will allow for future growth optimization.
Bibliographical noteFunding Information:
This work has been supported in part by the U.S. Department of Energy, NNSA Prime Award DE-NA0002565, and Washington State University Sub-award 118717-G003369; no official endorsement should be inferred. We are thankful for significant input of S.K. Swain, J.J. McCoy, S. Kakkireni, and K.G. Lynn of Washington State University. A. Yeckel provided support for this work though code development.
© 2016 Elsevier B.V.
- A1. Computer simulation
- A1. Convection
- A1. Crystal morphology
- A1. Heat transfer
- A1. Mass transfer
- B1. Semiconducting II-VI materials