Modelling laser-induced phase transformations in semiconductors

Three different approaches to modelling fast laser-induced phase transformations in Si are analyzed in the paper: the classical Stefan problem, a non-equilibrium model in which the Jackson–Chalmers response function is used at the interface, and a kinetic approach, in which both the nucleation mechanism and the kinetics of the new phase growth are taken into account. The simulations with the individual models give similar results on the maximum surface temperature, melt duration, melting depth and interface velocity. They differ in the values of the melt undercooling during the crystallization stage, its value being zero in the Stefan model naturally. The simulations performed with the second, non-equilibrium model have shown that the value of the undercooling decreases during the crystallization stage and differs for the (1 1 1) and (1 0 0) crystallographic orientations of the sample surface. The results of the simulations done with the third, kinetic model are characterized by a nearly constant value of the undercooling during crystallization. A comparison with available experimental data is presented and discussed.