Thermal properties and crystallization dynamics of a phase-change alloy for write-once optical data storage

Using a two-laser static tester, we measured the crystallization temperature and the thermal conductivity of a phase-change alloy thin film used in write-once–read-many media of optical data storage. The experimental technique, in general, and the calibration procedures, in particular, are described. The measurement results are used as entry points into numerical calculations that ultimately yield estimates of the material parameters. Valuable information about the dynamics of mark formation (i.e., localized crystallization) in amorphous phase-change alloy films is obtained from the observed variations of the sample reflectance under short-pulse and long-pulse recording conditions. The dependence of these reflectance variations on the laser pulse power has also been investigated.