High-voltage, high-resolution electron microscopy study on thin sections of phase change optical disk prepared by an ultramicrotome

Thin cross-sections of a phase change optical disk were prepared by ultramicrotomy without embedding of the resin. Transmission electron microscope images of the thin sections directly show the constitution of the phase change optical disk, that is, the coating layer (UV resin: 2.05 μm), the reflective layer (Al: 90 nm), the upper dielectric layer (ZnSμSiO₂: 37 nm), the recording layer (Ge₂Sb₂Te₅: 20 nm) and the bottom dielectric layer (ZnSSiO₂: 160 nm) on the pre-grooved polycarbonate substrate. Its structure on an atomic scale is analysed by high-voltage, high-resolution electron microscopy. Moreover, it is found that the characteristic of the phase change of the optical disk is attributed to the GeTe intermetallic compound of the recording layer formed during the initializing process.