High-Reflectivity Erasable CD

As CD-ROM market is getting larger year by year, write-once type recordable CD1) (CD-R) is consequently expanding its market scale for authoring tool of CD-ROM. We expect a fully backward-compatible erasable CD (CD-E) adds more attractive applications on CD-ROM world. In the CD-E, two important specifications in the CD Standard has to be conformed; high reflectivity of greater than 70% and large signal modulation of greater than 60%. The feasibility of the CD-E has been demonstrated2) using Ge-Te-Se phase-change material in a five-layer MIPIM structure, in which M, I and P denote metallic mirror, interference and phase-change layer, respectively. In the past study, full backward-compatible CD-E was achieved, however it required high laser power for writing, which is approximately 60mW on the disk, and less overwrite cyclability of 10 times. Our final goal in this study is to develop a practicable CD-E which has high performances in writing sensitivity and overwrite cyclability.