High-crystallization rate phase-change material for rewritable dual-layer disk

Abstract

A newly developed phase-change material, Sn-added Ge-Sb-Te, shows superior crystallization characteristics. The laser-crystallization time of the Ge-Sn-Sb-Te quaternary film was kept less than 50ns even in the case that the film thickness was reduced to 5nm. An experimental rewritable dual-layer optical disk was prepared with a Ge-Sn-Sb-Te quaternary film(6nm)and a Ge-Sb-Te ternary film(12nm)as the first and second memory layers, respectively, for achieving a specification corresponding to 27GB of capacity and 33Mbps of recording data rate utilizing a blue-violet optics(λ:405 nm, NA:0.65). More than 50 dB of C/N and more than 30dB of erasability were successfully obtained for the both layers with available recording laser powers of 8 and 11 mWs for the first and the second layers, respectively.