Effect of ZnS adhesion layer on overwrite cyclability of phase change optical recording media

A high-performance phase change optical recording disk, which has a five-la yered structure, was proposed. This disk has a ZnS adhesion layer between a GeSbTe recording layer and a ZnS-SiO2 second dielectric layer. A 2 x 10(5) overwrite cyclability was achieved with the original five-layered phase ch ange optical recording disk, The cross-sectional transmission electron micr oscope observation and the in-plane X-ray diffraction measurement indicate that both the five-layered disk and the four-layered disk have almost the s ame crystalline structure. The contact angle measurements, however, indicat e that the ZnS adhesion layer improves the adhesive force between the GeSbT e recording layer and the ZnS-SiO2. second dielectric layer. It is consider ed that the high overwrite cyclability results from this improvement of the adhesive force. Moreover, the electron probe microanalysis results indicat e that the ZnS layer acts as a protective layer against the Ge diffusion fr om the GeSbTe recording layer.