Silver-based compound metal island films for write-once optical data-storage media

Silver-based compound metal island (CMI) films prepared by use of a two-step evaporation method at the low substrate temperature of 20-30 degrees C have been experimentally investigated for write-once (WO) optical data-storage media. We found that most silver-based CMI films can be used as WO optical data-storage media provided that the island structure is formed in the films. Silver-gold CMI films are particularly useful as more-durable WO media for the 800-nm wavelength as compared with conventional silver island films. Aluminum-silver CMI films are potential WO media for a shorter-wavelength region, since the resonance wavelength exists near 500 nm. The spectral characteristics of the CMI films can be controlled by selection of the mixture ratio and evaporation order of metals. By use of CMI films, various specific WO optical data-storage media could be developed.