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

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.