EXPERIMENTAL AND THEORETICAL INVESTIGATIONS OF LASER-INDUCED CRYSTALLIZATION AND AMORPHIZATION IN PHASE-CHANGE OPTICAL-RECORDING MEDIA

We describe the numerical procedure for calculating three-dimensional profiles of temperature in a multilayer stack illuminated by a laser b eam, and model the crystallization and amorphization kinetics for phas e-change rewritable media. Experimental methods have been used to dete rmine indirectly the probabilities of nucleation and growth for Ge2Sb2 Te5 alloy. Some of the fundamental behaviors of phase-change erasable media, such as the crystallization of as-deposited amorphous phase, am orphization of supercooled liquid, and recrystallization of quenched a morphous phase, have been illustrated based on our three-dimensional t emperature calculations and the model kinetics. The calculated transie nt reflectance behavior of as-deposited Ge2Sb2Te5 amorphous films in a single layer and in a quadrilayer stack, as well as the erasure behav ior of Ge2Sb2Te5 alloy in a quadrilayer disk are in good agreement wit h experimental observations. (C) 1997 American Institute of Physics. [ S0021-8979(97)07821-3].