SUPERCOOLING AND STRUCTURAL RELAXATION IN AMORPHOUS-GE FILMS UNDER PULSED-LASER IRRADIATION

Melting and rapid solidification has been induced in amorphous Ge film s by irradiation with nano- and picosecond laser pulses. The degree of structural relaxation of the rapidly solidified amorphous material ha s been investigated both by determining the minimum fluence required f or surface melting and by means of Raman spectroscopy. The results evi dence that the degree of relaxation of the rapidly solidified material is controlled by several parameters such as the duration and fluence of the laser pulse, and the thermal conductivity of the substrate, all of them affecting the supercooling prior to solidification. It is dem onstrated that both relaxation and derelaxation can be induced if the above mentioned parameters are properly selected. The degree of relaxa tion is observed to decrease as the supercooling increases. (C) 1997 A merican Institute of Physics.