Compositional Dependence of Optical Constants and Microstructures of GeSbTe Thin Films for Compact-Disc-Rewritable (CD-RW) Readable with Conventional CD-ROM Drives

We studied the dependence of optical constants and microstructures of (GeTe)x(Sb2Te3)1-x films on composition to determine the optimal composition of phase change recording materials. The maximal differences in optical constants between crystalline and amorphous phases and the minimal crystalline grain sizes of the films were obtained at Ge39Sb10Te51. Using Ge39Sb10Te51 as a recording layer and TiO2 and SiO2 as interference layers, a compact disc rewritable (CD-RW) with 65% reflectivity and 60% modulation was obtained.