Solidification temperature of silicon surface layer melted by pulsed laser irradiation

Pyrometric measurements of the epitaxial crystallization temperature of Si have been carried out for the (100), (110) and (111) crystallographic orientations of the laser irradiated surfaces of the samples. A ruby laser pulse duration was 10(-7) s. Thermal radiation of melted Si was detected in green range of spectrum at the effective wavelength of 0.53 mu m The experimental data obtained have been analyzed on the basis of a nonequilibrium model of laser-induced liquid-crystal phase transitions. According to the experiment, the undercooling of the melt during the epitaxial growth on the (111)plane is about 35 K. The undercooling values corresponding to the (100) and (110) planes are equal and 13 +/- 2 K lower than that for the (111) orientation. Two kinetics regimes are considered. They differ in morphology of the liquid-solid interface which is atomically smooth if the interface moves in (111) direction or is atomically rough for the movement in the (110) and (100) directions. The orientation dependence of the epitaxial crystallization seems to be similar to that far the laser amorphization of Si. (C) 1999 Elsevier Science B.V. All rights reserved.