A unifying idea is presented for the engineering of convex melt-solid interface shapes in Bridgman crystal growth systems. Previous approaches to interface control are discussed with particular attention paid to the idea of a “booster” heater. Proceeding from the idea that a booster heater promotes a converging heat flux geometry and from the energy conservation equation, we show that a convex interface shape will naturally result when the interface is located in regions of the furnace where the axial thermal profile exhibits negative curvature, i.e., where d2T/dz2<0. This criterion is effective in explaining prior literature results on interface control and promising for the evaluation of new furnace designs. We posit that the negative curvature criterion may be applicable to the characterization of growth systems via temperature measurements in an empty furnace, providing insight about the potential for achieving a convex interface shape, without growing a crystal or conducting simulations.
Bibliographical noteFunding Information:
This work has been supported in part by the U.S. Department of Energy, under Awards DE-NA0002514 and DE-AC02-05CH11231 (LBNL Subcontract 7229320); no official endorsement should be inferred. We are thankful for significant interaction with D. Perrodin, G.A. Bizarri, and E.D. Bourret of Lawrence Berkeley National Laboratory.
© 2016 Elsevier B.V.
- A1. Computer simulation
- A1. Directional solidification
- A1. Heat transfer
- A1. Interfaces
- A2. Bridgman technique