Predicting thin film stoichiometry in V-O2 reactive sputtering

Abstract

The electrical, optical and mechanical properties of compound oxides film depend strongly on the composition of the film, especially for vanadium oxide thin films, since the vanadium-oxygen phase diagram includes mixed valence oxides with two or more oxidation states. Therefore, it is interesting to predict the film stoichiometry in VOx films. However, it has not, to any great extent yet, been possible to predict the composition of vanadium oxides films. In this article, we present a model that enables us to predict film composition of vanadium oxides prepared by reactive sputtering. Based on this model, the fraction ratio of V, V2O3, VO2 and V2O5 in the substrate surface as a function of oxygen flow is investigated. It is concluded that the presented theoretical model for the involved reactions and composition of VOx thin film during reactive sputtering process is in qualitative agreement with the XPS results from experiment and can be used to find optimum processing conditions for deposition of films of a desired composition.