Defect structure of V2O5 thin film gas sensors

Abstract

V2O5-undoped and Ti-doped thin films were deposited onto insulating support (either fused silica or alumina) by rf sputtering from metallic V target in a reactive Ar+O2 atmosphere. X-ray diffraction (XRD) and Scanning Electronic Microscopy (SEM) were used to structural and phase characterization. Electrical properties were determined by means of impedance spectroscopy (0.1 Hz – 1.4 MHz) at temperatures from RT to 620 K and oxygen partial pressure from 600 Pa to 21 kPa. It was found, that the studied samples can be characterized by an equivalent circuit composed of two ohmic resistors and non Debye constant phase element (CPE). Based on electrical conductivity vs. oxygen partial pressure dependence the point defect model has been proposed .