Development and characterization of a sprayed ZnO thin filmbased NO2 sensor

NO2 is one of the most harmful gases nowadays. A NO2 sensor based on sprayed ZnO thin film is reported in this work. Indium additive is used to improve the sensor performance, i.e. on the sensor response as well as on the sensor impedance, is studied. It was demonstrated that by adding 3 wt % of indium acetate to the spraying solution it is possible to enhance the film gas-response to 5 ppm of NO2 at 275 degrees C. At the same time the electrical resistance of the ZnO thin films significantly decreases in this case as a result of an effective doping process. Furthermore, the dependence of the electrical resistance on temperature in several gas atmospheres was also studied. The surface roughness was measured by atomic force microscopy (AFM). It was observed that doping increases the surface roughness and this fact plays an important role in the sensitization mechanism. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.