Melting and diffusion under nanosecond laser pulse

A computer simulation study of the melting process in Si, Ge and Sb under an UV laser beam was performed by means of the Finite Element Method (FEM). The melting threshold and melt duration of Si, Ge and Sb crystals were determined and a very good agreement with the Real Time Reflectivity (RTR) measurements is presented. SbGe-Si substrate multilayer systems are also studied. The simulated melt duration was lifted to the experimental data assuming 400 K undercooling of the molten layer prior to the solidification. Ge diffusion in the sample is also presented and the diffusion constant D = 7.5 × 10−5cm2/s was determined.