Studies on nanostructured V2O5/V/V2O5 films for un-cooled IR detector application

Abstract

Sensitive micro-bolometer devices require a sensor layer of high temperature coefficient of resistance (TCR) value with low resistance to reduce noise. Since it is difficult to produce vanadium pentoxide (V2O5) with high TCR and low resistance values, a sandwich type architecture approach was chosen, in which V2O5/V/V2O5 structure was formed using reactive direct current magnetron sputtering technique by varying the argon (Ar) and oxygen (O2) ratio. On increasing the O2 partial pressure, an increase in the crystallinity of the V2O5 film was observed using X-ray diffraction (XRD) studies, which was due to the availability of abundant oxygen to form V2O5. X-ray photoelectron spectroscopy (XPS) result of V2O5/V/V2O5 indicated a decrease in V2p peak and increase in O1s peak, confirmed the multilayer had mixed vanadium oxide phases of V3+ and V2+ oxides of vanadium due to the diffusion of oxygen from top and bottom V2O5 layer into the V metal layer. V2O5/V/V2O5 multilayer films at the higher O2 ratio had TCR value −2.5 %/°C with a resistivity of 19 Ω/cm−1, which is compatible for un-cooled IR detector application.