Solid Phase Superheating During Picosecond Laser Melting of Gallium Arsenide

Abstract

AbstractThe velocity distributions of atoms evaporated from the surface of GaAs during laser heating with nanosecond and picosecond pulses are measured. The atomic velocities provide information about the surface temperature. For picosecond heating we observe a continuous transition of the temperature across the melting point, whereas for nanosecond heating the melting point is marked by a distinct plateau of the temperature curve. From these observations we conclude that the solid is strongly superheated during picosecond irradiation. A detailed analysis suggests superheating of typically a few hundred degrees above the melting point.