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 VxOy between 300-400 °C, which gets fully converted into V2O5 after annealing at higher temperatures ∼450 °C. The local conversion from VxOy 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.