Gas Sensing Characteristics of Zinc-Tin Complex Oxide Thin Films with Spinel-Type Structure

Zn-Sn metallic films were deposited on alumina substrates by an evaporation method, and then complex oxide films were fabricated by annealing in air. The relation between the formation of spinel-type Zn2SnO4 and their sensing characteristics to i-C4H10 gas was studied. Both ZnO and SnO2 films annealed at 500°C had higher sensitivity to i-C4H10 than the complex oxide films of ZnO and SnO2 because of fine crystallinity. The sensitivities of the complex oxide films increased with increasing annealing temperature from 600 to 800°C, because of the improved crystallinity. Higher sensitivities were obtained by laminating the complex oxide films. Moreover, the gas selectivity of Zn-Sn complex oxide films for several kinds of gases was investigated. The Zn-Sn complex oxide film had a very high sensitivity to NO2 gas.