Infrared sensitive mixed phase of V 7 O 16 and V 2 O 5 thin-films.

We report an infrared (IR) sensitive mixed phase of V 7 O 16 and V 2 O 5 thin films, grown by cathodic vacuum arc-deposition on glass substrates at relatively low temperatures. We have found that the mixed phase of V 7 O 16 and V 2 O 5 can be stabilized by post-annealing of amorphous V x O y between 300-400 °C, which gets fully converted into V 2 O 5 after annealing at higher temperatures ∼450 °C. The local conversion from V x O y to V 2 O 5 has also been demonstrated by applying different laser powers in Raman spectroscopy measurements. The optical transmission of these films increases as the content of V 2 O 5 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 V 7 O 16 degenerate semiconductor.