REFRACTIVE-INDEXES OF THE TUNGSTEN-OXIDE FILMS PREPARED BY SOL-GEL AND SPUTTERING PROCESSES

Tungsten oxide films were prepared by sol-gel and sputtering processes. The refractive indices and extinction coefficients of the films were calculated from the transmittance and reflectance spectra in the visible and infrared regions, The films were transparent in the visible and infrared regions when they were prepared by the sol-gel process and fired at 300 degrees C and 500 degrees C, and by the sputtering process under the conditions of O-2/Ar=0.05 and 0.1 at room temperature. The refractive indices of the films depended on preparation conditions. The extinction coefficients of the films were almost zero in the visible and infrared regions. On the other hand, film prepared by the sputtering process under the condition of O-2/Ar=0.01 was blue colored, The refractive index of the film increased with increasing wavelength in the visible and infrared region. The extinction coefficient of the film showed a large value at 1450 nm, which corresponds to the minimum of the transmittance spectrum of the film.