Measurement of the Velocity of the Crystal-Liquid Interface in Pulsed Laser Annealing of Si

The conductance of Au-doped Si single crystals was measured during irradiation with 30-nsec $Q$-switched ruby-laser pulses at energy densities above the Si melting threshold (∼0.9 J/${\mathrm{cm}}^2$). The sample conductance is determined primarily by the thickness of the molten layer so that the solid-liquid interface velocity can be found from the current transient. The interface velocity during crystallization was found to be 2.7±0.1 m/sec, in close agreement with calculated values based on a heat-flow model.