Infrared optical properties of evaporated alumina films.

The dielectric function epsilon identical with epsilon(1) + iepsilon(2) has been determined for Al(2)O(3) films prepared by electron beam evaporation, in the 5-50-microm wavelength range. The data were extracted from spectrophotometric recordings of transmittance and reflectance by use of a novel technique. Supplementary measurements were made of the refractive index for visible and near-infrared wavelengths and of the dielectric constant at 1 MHz. Kramers-Kronig analysis was employed to check the consistency of our results for epsilon(1) and epsilon(2).