Characterization of a WO3 thin film chlorine sensor

A semiconducting metal oxide (SMO) gas sensor for the detection of chlorine has been developed and characterized. A WO3 thin film has been used as the sensing element. The sensors were found to respond to sub-ppm chlorine concentrations by a reversible decrease in conductivity up to three orders of magnitude, depending on operating temperature and sensor design parameters such as electrode material. The influence of annealing on sensor performance is discussed. Several observations in the gas sensing experiments as well as preliminary X-ray photoelectron spectroscopy (XPS) results give some insight into the chemical and physical processes underlying the sensor response. (C) 2001 Elsevier Science B.V. All rights reserved.