A KrF (248 nm) pulsed laser was used to melt 90-, 190-, and 440-nm thick
amorphous silicon layers produced by Si ion implantation into (100)
crystalline Si substrates. Time-resolved reflectivity measurements at two
different probe wavelengths (633 nm and 1.15 μm) and post-irradiation TEM
measurements were used to study the formation of an undercooled liquid Si
phase and the subsequent solidification processes. The time-resolved
measurements provide new experimental information about the nucleation of
fine-grained Si crystallites in undercooled liquid Si, at low laser energy
densities (Eℓ), and about the growth of large-grained Si in the
near-surface region at higher Eℓ. Measurements with the infrared
probe beam reveal the presence of a buried, propagating liquid layer at low
??. Model calculations indicate that this liquid layer is generated in part
by the release of latent heat associated with the nucleation and growth
process.