Electrical Properties of Palladium-Coated Indium Oxide Films for Gas Detection

Noble metal was coated on In2O3 polycrystalline films to evaluate the sensitivity of an n-type semiconductor to several types of flammable gas. The film formation of Pd increases the surface resistivity as compared with the initial resistivity of as-deposited In2O3 films. During the exposure to the flammable gas, the resistivity of the In2O3 film decreases. As the difference between initial resistivity and that during exposure to flammable gas becomes large, the gas sensitivity of Pd-coated In2O3 becomes sufficiently high.