A COMPUTER-SIMULATION OF CRYSTAL-GROWTH BY THE TRAVELING-SOLVENT METHOD (TSM) - PSEUDO-STEADY-STATE CALCULATIONS

A computer simulation is conducted to study single-crystal growth by t he traveling-solvent method (TSM) using a pseudo-steady-state model. T he model, which is governed by momentum, heat, and mass balances in th e system, is solved by a finite-volume/Newton method. Flow patterns, t emperature and solute distributions, and unknown melt/solid interfaces are calculated simultaneously. The model is mainly developed for bina ry compounds for which the solubility of solvent in solid materials is negligible. In such a system, an integrability condition, which resul ts from an overall solvent balance, is required to ensure the unique s olution of solute fields in the computation. Sample calculations are r eported for CdTe, a II-VI-compound semiconductor, grown from Te solven t. Due to strong coupling of solute and temperature fields and fluid f low, as well as phase equilibrium, the effect of convection on the int erface morphology and zone position is significant in such a system. T hrough computer simulation, the effects of some process parameters, in cluding the growth speed, heater temperature, and initial solvent volu me, on interface shapes, convective mass transfer, and constitutional supercooling at different degrees of convection are also demonstrated.