Infrared sensitive mixed phase of V7O16 and V2O5 thin-films

Abstract

We report an infrared (IR) sensitive mixed phase of V₇O₁₆ and V₂O₅ thin films, grown by cathodic vacuum arc-deposition on glass substrates at relatively low temperatures. We have found that the mixed phase of V₇O₁₆ and V₂O₅ can be stabilized by post-annealing of amorphous V_xO_y between 300–400 °C, which gets fully converted into V₂O₅ after annealing at higher temperatures ∼450 °C. The local conversion from V_xO_y to V₂O₅ has also been demonstrated by applying different laser powers in Raman spectroscopy measurements. The optical transmission of these films increases as the content of V₂O₅ increases but the electrical conductivity and the optical bandgap decrease. These results are explained by the role of defects (oxygen vacancies) through the photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements. The IR sensitivity of the mixed phase is explained by the plasmonic absorption by the V₇O₁₆ degenerate semiconductor.