Picosecond laser melting and evaporation of GaAs surfaces

Picosecond laser-induced melting and evaporation of GaAs surfaces are studied. The high reflectivities of molten GaAs observed at fluences above the melting threshold have a wavelength dependence inconsistent with a simple Drude model for a metallic molten GaAs surface. The observations at high laser fluences suggest that the liquid-vapor phase transition is initiated by a fast-expanding, high-density fluid.