High-sensitivity silicide films for optical recording

The laser writing power for near-noble metal silicide films has been reduced significantly by several techniques including amorphization of the thin metal films and fabrication of trilayers. Rh films alloyed with B by thermal evaporation from an alloy slug (containing 10 wt. % B) show no crystalline structure. In bilayer structures consisting of RhB (250 Å) and Si, the characteristic reflection minimum is found to decrease in magnitude and to shift toward longer wavelength: 20% at 6000 Å for 150-Å-thick Si to 8% at 10 000 Å for 400-Å-thick Si. Static laser writing power on samples deposited on polymethyl methacrylate substrates for half-saturation of contrast with 50 ns pulse width at 6417 Å is 18 mW. Further reduction in writing power was achieved by fabrication of a trilayer structure consisting of Al(300 Å)-SiO₂(900 Å)-Au(60 Å)-Si(60 Å). Typical writing power is below 10 mW for spot size slightly smaller than 1 micron.