Effect of Tl and Metallic Element Addition to In–Se Based Phase-change Optical Recording Film

Abstract

The mechanism of fast crystallization of In-Se phase-change optical recording films by Tl addition is studied determining atomic arrangement by XPS and using crystallization kinetics of a written amorphous state. Thallium ions in the In-Se-Tl film found to be monovalent, so they cut atomic bonds. The minimum crystallization time by an laser-beam irradiation is shorten to 0.2µs by the Tl addition. The Tl addition increases both the activation energy and frequency factor for crystallization. Cobalt addition to the In-Se-Tl film not only stabilizes amorphous state but also makes erasing faster. The minimum crystallization time is further shorten to 0.06 µs. The retention time of written dot's amorphous state is estimated to be 100 years at 150°C. More than 2500 times of single-beam overwrite is achieved using In-Se-Tl-Co disk. Carrier to noise ratio of a 2.5MHz signal is 54dB at 1800rpm.