New Materials Consisting of Multicomponent Oxides for Thin‐Film Gas Sensors

Abstract

High sensitivity for specific gas detection has been realized by new gas sensors incorporating multicomponent oxide thin films such as , and systems. The sensing properties of the multicomponent oxide thin‐film sensors were strongly dependent on the composition of the films used. Sensors using ternary compounds such as and always exhibited a higher sensitivity than those using binary compounds such as ZnO and . The sensors only exhibited an increase in resistance with exposure to carbon tetrachloride gas, whereas they exhibited a decrease in resistance for inflammable gases such as butane and hexane . The highest sensitivity for gas was obtained in a sensor using a thin film prepared with a content of about 60 mole percent. The resistance of sensors operated at 300°C was increased by a factor of about 102 when exposed to gas with a concentration of 350 ppm. The increase in resistance is attributed to the trapping of free electrons resulting from chlorine being adsorbed on grain boundaries and/or the film surface.