Temperature, composition and microstructure variations during pulsed laser irradiation of a deposited film on a substrate

Abstract

A computer model has been developed to describe melting and resolidification during laser irradiation of elemental and alloy films on a substrate. The computer model predicts the temperature profile, maximum melt depth, maximum solidification rate, onset of cellular breakdown and the final resolidified composition profile. The computer model has been compared with measurements [I. T. H. Chang and B. Cantor, J. Thin Solid Films230, 167 (1993)] made on cross-section TEM specimens of 1.15 J/cm²irradiated 400 nm thick Sn and 0.96-1.17 J/cm²irradiated 120 nm thick Ge-50 at.% Sn films on single crystal Ge substrates. The predicted results give good agreement with the measured data. The maximum melt depth increases with increasing laser energy density. Cellular breakdown takes place at increasing depth with increasing laser energy density.