Modeling of nonequilibrium melting and solidification in laser-irradiated materials

Abstract

A computational model has been developed for treating various aspects of the complex melting and solidification behavior observed in pulsed-laser-irradiated materials. An important feature of the modeling is the capability of allowing nonequilibrium melting and solidification to occur at temperatures other than the thermodynamic phase-change temperatures. As a result, interfacial undercooling and overheating can be introduced and various types of nucleation events can be simulated. Calculations for pulsed-laser-irradiated silicon containing amorphous layers have shown a wide variety of behavior, including the formation and propagation of multiple phase fronts and buried molten layers. Although originally developed as a tool for studying problems arising in the field of laser annealing of semiconductors, the approach used in the modeling should be useful in treating many types of systems in which ultrarapid phase change and nucleation phenomena play important roles.