Optical properties of coevaporatedAgSiOxcermet films

Measurements have been made of the optical properties of coevaporated ${\mathrm{AgSiO}}_{\mathrm{x}}$ cermet films. Films varying in metal fraction from 0% to 100% were prepared in a residual oxygen atmosphere, and at slow evaporation rates, to give oxygen-rich films. Measurements of reflectance and transmittance were inverted to give the complex dielectric constant by an iterative method using a Kramers-Kronig integral of the transmittance. The results are compared with the Maxwell-Garnett and Sheng effective-medium theories for spherical particles. A previously unreported peak in the imaginary part of the dielectric constant was observed for high-volume-fraction cermets. A number of films were examined with a transmission electron microscope.