Picosecond Dynamics of Pulsed Laser Annealing of Ion-Implanted Silicon

The temporal changes in the reflectivity of ion-implanted silicon during picosecond pulsed laser annealing were measured with a single laser shot by using a streak camera. The rise times to the enhanced reflectivity of ∼70% were found to be 300 ps and 100 ps under 1.06 µm and 532 nm excitation, respectively, at an incident energy density just above the melting threshold. The rise time decreased with increase in incident energy density. Under 1.06 µm excitation, phonon emission took place as a result of the Auger recombination of carriers, and the melt-front velocity was smaller than that under 532 nm excitation. These factors are considered to be responsible for the difference observed between the two kinds of excitation. At higher incident energy densities, the overheating of liquid silicon was found to occur.