Simulation study of phase-change optical recording disks

Effects of phase change in the recording layer due to temperature changes a nd ihs material parameters used in the simulated transient temperature dist ributions were examined. The initial structure of the recording layer was t he key parameter for simu lated temperature distributions in both the erasi ng and writing processes. Latent heat due to the phase change had little ef fect on the transient temperature distributions, however, the temperature-d ependent heat capacity had significant effects and resulted in a transient temperature distribution level lower than that using a constant room-temper ature capacity value. From the simulated transient temperature profile, coo ling rate, dependence of phase-changed spot size on the laser power and las er pulse duration, as well as the phase-change characteristics in the phase -change optical disk, could be obtained. By applying proper material parame ters, the disk with a hydrogenated amorphous carbon film as the top dielect ric layer with a disk structure of PC/ZnS-SiO2 (111 nm)/GeSbTe(20 nm)/alpha -C:H (63 nm)/Al(70 nm) showed less temperature variation between the center and the edge of the irradiated spot than that of a disk with a conventiona l disk structure of PC:ZnS-SiO2(144 nm)/GeSbTe (20 nm)/ZnS-SiO2(21 nm)/Al(7 0 nm). Less temperature variation may give rise to a written spot with more uniform microstructures.