Optical characterization of multilayer stacks used as phase-change media of optical disk data storage

We report results of measurements of the optical constants of the dielectric layer (ZnS-SiO₂), reflecting layer (aluminum–chromium alloy), and phase-change layer (GeSbTe, AgInSbTe) used as the media of phase-change optical recording. The refractive index n and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.