New gas sensing mechanism for SnO2 thin-film gas sensors fabricated by using dual ion beam sputtering

A new gas sensing mechanism for SnO2 thin-films fabricated by using dual io n beam sputtering, was proposed. The features of the SnO2 thin-film conside red in this study had been characterized as having extremely smooth surface , dense microstructure and near stoichiometric SnO2 phase. In this study, t hus, the problems of reported gas sensor models were noticed briefly and ne xt, a novel sensing model for the SnO2 thin-films prepared in this study wa s approached by geometrical considerations. The effects of resistivity in t he bulk regions and in the depletion regions on the gas sensitivities were studied by fabrication of thin-film gas sensors having various film thickne ss. The proposed gas sensing mechanism was verified by the fabrication of a H2S sensor with p-n junctions. (C) 2001 Elsevier Science B.V. All rights r eserved.