OPTICAL-PROPERTIES OF SPUTTERED FE2O3 FILMS

The optical transmission and reflection characteristics of Fe2O3 films prepared by r.f. sputtering were measured at wavelengths between 0.4 and 1.1 microm using a simple apparatus. From these data the refractive indices and extinction coefficients for wavelengths above 0.5microm could be derived using a homogeneous film model. Both quantities depend essentially on such preparation conditions as the substrate temperatures and plasma parameters. For instance, the refractive indices and the extinction coefficients of films produced on water-cooled substrates are about 10% and 20-30% respectively lower than for films sputtered onto substrates at a temperature of about 350°C. These differences can be explained easily by assuming that the films have different densities. Density measurements on thicker films and differing growth rates seem to confirm this assumption. Scanning electron micrographs show a columnar structure. At wavelengths below 0.5 microm the refractive indices deduced from measurements form the front side of the films differ from those deduced from measurements from the back (substrate) side indicating the limited validity of the homogeneous film model. © 1979.