Infrared sensitive mixed phase of VO and VO thin-films.

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