Fast melting of amorphous silicon carbide induced by nanosecond laser pulse

We report the first experimental detailed study of laser induced surface me lting on the nanoscale time scale of amorphous silicon carbide layers produ ced by ion implantation. Time-resolved reflectivity has been used to observ e the fast liquid-solid-liquid transition features, and transmission electr on microscopy (TEM) was used in order to study the structure resulting afte r the Fast solidification following the laser induced melting. By means of the evaluation of the laser fluences required to induce melting of amorphou s layers of different thickness on top of a crystalline substrate, we evalu ated the thermal diffusion coefficient and the melting point of the amorpho us material which occurred much lower than for crystalline material. Moreov er, we give evidence of amorphous-to-crystal transitions occurring in the s olid phase on the nanosecond time scale, for laser irradiation at fluences below the melting threshold. A quite different crystalline structure is obs erved for crystallization From the liquid phase than from the solid phase.