Refractive indices of TiO(2) films produced by reactive evaporation of various titanium-oxygen phases

In this paper experiments with reactive evaporation of the starting materials Ti, TiO, Ti(2)O(3), Ti(3)O(5), and TiO(2) to obtain nonabsorbing TiO(2) films are under discussion. For the starting materials TiO and Ti(3)O(5) the dependence of the TiO(2) film refractive index on the substrate temperature, oxygen pressure, and deposition rate was measured. For TiO dispersion curves of the resulting TiO(2) films as a function of the substrate temperature during film formation were determined. The successive evaporation of the different starting materials resulted in the formation of lambda/4 TiO(2) films with different refractive indices. This phenomenon was most obvious during the first evaporation. It disappeared after several evaporations in two groups of TiO2 films with different refractive indices. From the beginning only the starting materials Ti and Ti(3)O(5) resulted in TiO(2) films with constant refractive indices. The first material produced a high, the latter a lower film index. Depending on the number of evaporations performed, both types of TiO(2) films can be obtained with TiO. The films and residues in the crucibles were also subjected to chemical analyses. An attempt was made to explain the optical properties of the resulting TiO(2) films with regard to crystal structure, chemical composition, packing density influenced by the molecular composition of the vapor beam, chemical reaction with the crucible, substrate temperature, O(2) pressure, and deposition rate.