Potential of Ge-Sb-Te phase change optical disks with high speed overwrite ability

Increase of data transfer rate is one of the most important theme for an optical disk used in multi-media systems. Certainly it is required for an optical disk to treat the data of high quality motion pictures and to store LAN data directly. We first proposed Ge-Sb-Te material in Jpn. J. Appl. Phys. Supp.26-4, p.61, 1987; since then we have been studying high speed overwritable phase change media and last year commercialized a professional use of a digital video disk recorder whose data transferring rate is 40 Mbps by increasing the linear velocity to 27 m/s. In this paper, I will review our R&D results in this field and estimate possible performance of high speed phase change optical disks in the near future.