Electrical properties of reactively sputtered WO3 thin films as ozone gas sensor

Electrical properties of the metallic oxide semiconductor, such as tungsten trioxide (WO3) thin films, deposited on SiO2/Si substrates by RF reactive magnetron sputtering system from a metallic tungsten target and argon-oxygen mixture gas have been investigated. This study is devoted to analyse the relationship between the electrical properties and the WO3 thin film deposition parameters (substrate temperature, oxygen partial pressure, annealing) and the sensitivity and stability of these WO3 gas sensors. The surface morphology evolution of these films has been investigated by atomic force spectroscopy (AFM). Two types of electrical measurements were performed: conductivity versus temperature and some tests under ozone at different temperatures. The activation energy evolution is correlated with the reactivity of surface sensors under oxygen partial pressure. (C) 2002 Elsevier Science B.V. All rights reserved.