Thermodynamic properties of amorphous silicon investigated by pulsed laser heating

Nanosecond (=347 nm, =25 ns) and picosecond (=532 nm, =20 ps) pulsed laser irradiation have been used to induce surface melting in ion implanted and annealed amorphous silicon layers. Time-resolved reflectivity technique was employed to detect the melting onset, from which the melting temperatures of the amorphous phases have been evaluated. Thermal properties of the relaxed amorphous have also been investigated, and in particular, the differences in the heat capacity and in the thermal conductivity of the relaxed amorphous with respect to the as-implanted one were determined. Using these results, the free energy diagram of both relaxed and unrelaxed amorphous silicon has been constructed.Paper presented at the Second Workshop on Subsecond Thermophysics, September 20–21, 1990, Torino, Italy.