A Thin Film of an Ni–NiO Heterogeneous System for an Optical Recording Medium

Abstract

The authors have found a write once read many (WORM) type new optical recording medium of an Ni–NiO heterogeneous system thin film. The structure of the recording medium is a single layer Ni–NiO heterogeneous thin film on a transparent resin substrate. Irradiation of a converged laser diode beam causes a volume expansion of the film to form a swell. Information reading is done by using its reduction in reflectivity. The recordable composition region of this film is considered to be the transitive region from the metal to the oxide. The volume expansion is assumed to be induced by the oxidation of the Ni–NiO heterogeneous thin film and the height of the swell is estimated. This value agrees well with the measured top height of the swell.