Computational simulations of pulsed laser induced melting and solidification of monocrystalline GaSb

Numerical analysis of pulsed laser induced phase change processes in the near-surface region of monocrystalline bulk GaSb is done using a thermal nonequilibrium model. The calculations of basic parameters of the processes such as surface melt duration, maximum reflectivity of the probe laser beam, etc., are verified using results of experimental work on GaSb samples irradiated by the ruby (694 nm, 35 ns FWHM) and ArF (193 nm, 13 ns FWHM) lasers. The comparison of experimental data with numerical predictions shows that while for the ruby laser a reasonable agreement in surface melt duration is achieved, the results for the ArF laser differ quite a lot. The amorphization of the topmost surface layer is identified as a main reason for these differences. The subsequent experimental analysis of the surface structure by low energy electron diffraction (LEED) and Auger electron spectroscopy (AES) confirms the theoretical predictions and clearly indicates the appearance of an amorphous GaSb structure after ArF laser irradiation.