Optical properties of tin‐doped indium oxide determined by spectroscopic ellipsometry

Sputtered tin‐doped indium oxide (ITO) coatings were investigated by UV‐visible spectroscopic ellipsometry at different angles of incidence. The results were fitted using a classical dispersion formula for the optical constants of ITO in a model structure with a compact homogeneous film and a top layer representing surface roughness. Typical values for the high‐frequency dielectric constant e∞ and the plasma frequency ωp were found to be 3.4–4.0 and 0.68–0.96 eV, respectively. The influence of oxidative and reducing annealing at 400 °C was studied. No difference was observed under reducing conditions, but oxygen annealing reduced the influence of the plasma frequency on the studied UV‐visible region significantly. To prove the usefulness of the dispersion formula, TiO2 and Nb2O5 films were grown on ITO by metalorganic chemical vapor deposition using Ti(acac)2(i‐pro)2 and Nb(OEt)5 as precursors. These bilayers were studied by spectroscopic ellipsometry and could be successfully described applying the previ...