Computational solution of a two-phase moving boundary problem with two moving interfaces in pulsed laser processing of semiconductors

摘要

A model of melting, evaporation and solidification of a binary alloy due to pulsed laser irradiation is formulated using the mass and internal energy balances in the liquid and solid phases, the vapor being assumed to be removed from the sample surface into vacuum instantaneously. The interface between the solid and liquid phases is modeled as a discontinuity surface where, in addition to balance conditions, an interface response function is formulated on the basis of the Wilson-Frenkel theory so that both melting and solidification are treated as nonequilibrium processes. The liquid/vapor interface is modeled in a similar way, with an interface response function defined on the basis of the kinetic theory of gases. The numerical solution of the mathematical model is performed using the Galerkin finite element method combined with a front-fixing technique. The practical applicability of the computational model is demonstrated on the numerical simulation of phase change processes in CdZnTe pseudobinary system induced by NdrYAG laser.