Silver-particle-dispersed silver-oxide film: a dual-function write-once recording material

Abstract

Silver oxide thin-films with various silver oxides concentration and silver particles amounts are prepared via magnetron sputtering techniques with oxygen reactive gas by varying deposition parameters. The presence of silver particles in the inorganic silver oxide compound was detected by x-ray diffraction. Heat measurements of the powdered silver oxide film via thermogravimetry analyzer (TGA) show that the powdered silver oxide decomposes and releases oxygen at a temperature of about 355°C. The oxygen concentration can be estimated by TGA weight loss. The optical reflectance and extinction coefficient of the silver oxide film confirm the dual function of the silver particles present in the film. The silver particles served both as the laser beam light absrober and reflectance centers for laser beam. With the presence of the silver particles in the silver oxide film, the reflective layer used in the prior art can be dispensed with. A single layer disk-silver dispersed silver oxide film, which served both as the recording layer and the reflective layer, deposited on the digital versatile disk-recordable (DVD-R) polycarbonate substrate is prepared. Since the plastic substrate is softened at a temperature of about 140°C, the silver oxide recording layer decomposes and releases oxygen when the recording medium is irradiated with a laser beam so as to permit formation of recesses in the plastic substrate and so as to permit a sharp change in reflectivity at positions where the recessions are formed. The characteristics of this single layer DVD-R disk are demonstrated.