Preparation of Magnetron-Sputtered Ag--Zn Alloy Films for an Erasable Optical-Disk

Thin films of Ag--Zn ( approx 50 at.% Zn) binary alloy exhibit a reversible color change between silver and pink, depending on the thermal history of the film. The films can be used for optical recording with a laser beam. Characterizations were made of the thin films prepared by DC magnetron sputtering with a two-component target of Ag and Zn sheets. The Ag--Zn alloy film showed the reversible color change when the Zn composition of the film was close to 50 at.% Zn and the substrate temperature was at approx 150 deg C during the sputter-deposition. An X-ray diffraction pattern obtained from the pink color film showed CsCl-type beta ' phase (bcc) structure, and the pattern from silver color film showed zeta phase (hcp) structure. Measured were light reflectivities vs. wavelength of the pink and silver color films. The difference in reflectivity approx 800 nm, which corresponds to semiconductor lasers, between the pink and silver color films was 20%. 4 ref.--AA