Investigation on synthesis, characterization, and electronic behaviour of zinc oxide thin films in relation to fabrication of oxygen gas sensor

The zinc oxide thin films were prepared by spray pyrolysis method. The films were characterized by means of X‐ray diffraction and scanning electron microscopy techniques. The annealing treatment at 300 ± 30 °C for 15 and 30 hours improved the crystallinity of the film and also led to a homogeneous film surface. The O2 gas sensing properties of the zinc oxide thin film were studied by investigating the variation of the electrical resistance of the film as a function of O2 partial pressure at various temperatures. The gas sensing property was found to depend on the film characteristics in regard to its state of crystallinity and surface conditions. The gas sensing property was also dependent on the temperature at which the sensing was done. The optimum oxygen gas sensivity was obtained when the temperature of the zinc oxide sensor was maintained at 400 °C. The study reveals that sprayed zinc oxide thin films may be used as a low cost solid state oxygen gas sensor.