W O 3 ∕ metal thin-film bilayered structures as optical recording materials

Interface reactions in $\mathrm{W}{\mathrm{O}}_3∕\text{metal}$ thin-film bilayered structures were examined for applications to optical recording materials. Decreases in the reflectance of the structures caused by temperature elevation were observed and were attributed to (i) coloration of the $\mathrm{W}{\mathrm{O}}_3$ layers, and (ii) decreases in the reflectance of the metal layers resulting from redox reactions between the $\mathrm{W}{\mathrm{O}}_3$ and the metals. The reflectance spectra of the structures before temperature elevation showed moderate wavelength dependence over a wide range, from the visible to the near infrared. Decreases in the reflectance due to temperature elevation occurred over a wide wavelength range. Examination of the $\mathrm{W}{\mathrm{O}}_3∕\mathrm{Al}–\mathrm{Ti}$ bilayered structures as potential optical disk memories revealed that the redox reactions occurred within submicrosecond time periods during irradiation with the recording laser. The results indicate that these structures possess promising properties for applications to optical recording materials that can be used over a wide wavelength range.