On the Interpretation of Time-Resolved Surface Reflectivity Measurements during the Laser Annealing of Si Thin Films

Abstract

Time-resolved surface reflectivity measurements of nanosecond pulse laser-annealed Si thin films are compared to the simultaneously measured reflectivity of the interface between the film and glass substrate. In the case of complete melting of the film the liquid is supercooled. The measurements of the interface reflectivity show that the resolidification process starts at the interface. The resolidification at the surface occurs after an energy-dependent delay of up to 40 ns. The analysis of the data shows that during this delay time the surface temperature may be increased by the latent heat released at the interface. This reheating effect of the surface, which has not been considered yet demands for a careful interpretation of surface reflectivity measurements.