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“Explosive” or self-sustaining crystallization of amorphous thin films has been observed by many workers, most recently in connection with laser annealing experiments. The origin of this phenomenon is thermal; once initiated, the heat liberated by the transformation raises the temperature of adjacent material sufficiently to allow rapid crystallization. We have analyzed this effect using a one-dimensional heat-conduction equation. The amorphous-crystalline interface temperature T resulting from an imposed interface speed V is compared with the intrinsic growth rate V(T) as a test for unassisted propagation. A steady-state analysis yields the primary experimental trends. For materials that possess structurally distinct amorphous and liquid phases, the possibility that melting occurs before crystallization is considered, and the thickness of the molten zone is predicted.

A metastable Pt-Si phase of approximately PtSi 2 stoichiometry has been formed by msec duration irradiation of Pt films on silicon with a free running Nd:YAG laser. The silicide forms epitaxially on (111) silicon, exhibits low (50–60 μΩcm) resistivity, and excellent surface smoothness. The alloying reaction occurs at the Pt-Si interface and proceeds towards the free Pt surface. Neither the composition nor the structure of the metastable phase corresponds to previously reported Pt-silicides.

Laser induced melting and resolidification of single crystal silicon introduces electrically active point defects. The electrical properties of laser processed silicon were monitored by capacitance transient spectroscopy (DLTS) and thermally stimulated capacitance (TSCAP) measurements. Removal of residual defects by thermal annealing occurs between 500°C and 700°C. More importantly, the defects are passivated by reaction with atomic hydrogen in the temperature range of 100–300°C.

125 nsec pulses of λ = 1.06 μm light from a Nd:YAG laser have been used to convert amorphous, vapor deposited layers of Ge and Ge + Si on (100) Si substrates to epitaxial heterostructures. Pulse energy densities in the range from 4 to 12 J/cm 2 melt the deposited layers, which regrow epitaxially. A cellular defect structure is formed in the resolidified material via a cellular crystal growth mechanism.