Filmes finos de óxidos de vanádio depositados por sputtering reativo

Abstract

We have produced thin film samples of vanadium oxide, with different stoichiometry, by reactive magnetron sputtering from a metallic vanadium target. The thickness of the samples were maintained under 100 nm and glass or silicon wafers, heated up to 440°C, were used as substrates. During the deposition, the gas atmosphere of Ar+O2 were kept in 7.5 mTorr and the partial oxygen pressure was ranging between 0.8 and 1.5 mTorr. The structural composition of the thin films was determinate, at room temperature, by X ray diffraction in the theta-2theta geometry, where the theta angle was varied from 10 to 45 degrees. All the samples have shown more than one vanadium phase in the range of partial pressures analyzed. The oxides are texturized and with grain sizes depending on the phase. For the smallest oxygen partial pressure, two different phases (tetragonal and monoclinic) of VO2 are predominant. As the pressure increases, oxides richer in oxygen like V2O5 are also present. RX results support the resistivity behavior as a function of the temperature measured in the samples. We suggest some procedures that allow the preparation of single phase vanadium oxide samples.