Tuning of the response kinetics by the impurity concentration in metal oxide gas sensors

Thin and ultra-thin tin and indium oxide films sensitive to gas are modified by the post-growth deposition of metallic impurities on the surfaces of the films. An influence of this modification on the response to gas kinetics are studied when the sensor parameters are tuned by a gradual change of the impurity metal amount on the surfaces of the metal oxide films. Based on original phenomenological model, the parameters of the response kinetics are related to the rate parameters of the surface chemical reaction. The model is used to explain the changes of the response kinetics with the impurity amount. The surface properties, characterised by X-ray photoelectron spectroscopy, secondary electron microscopy and atomic force microscopy, are considered in this study.