SPRAY-PYROLYSIS PREPARATION AND HUMIDITY SENSING CHARACTERISTICS OF SPINEL ZINC STANNATE THIN-FILMS

Polycrystalline spinel Zn2SnO4 films were successfully deposited on al umina substrates by spray pyrolysis. It was found that the ratio of th e two cations in the films obtained differs considerably from the rati o in the initial solutions. By optimizing the solution compositions an d the deposition and heat-treatment parameters, it was possible to obt ain homogeneous single phase films with good adhesion to the substrate , At room temperature the electrical resistance of the films was stron gly dependent on humidity, the response and recovery times being very short (1-2 min), The humidity sensing characteristics deteriorated in the presence of a binary oxide (ZnO or SnO2) impurity in the film. (C) 1997 Academic Press.