In this paper a novel type of a highly sensitive gas sensor device based on the surface photovoltage effect is described. It is based on the Kelvin probe approach. Porous ZnO nanostructured thin films deposited by the direct current (DC) reactive magnetron sputtering method are used as the active gas sensing electrode material. Crucially, the obtained gas sensing material exhibited a nanocoral surface morphology and surface Zn to O non-stoichiometry with respect to its bulk mass. Among other responses, the demonstrated SPV gas sensor device exhibits a high response to an NO₂ concentration as low as 1 ppm, with a signal to noise ratio of about 50 and a fast response time of several seconds under room temperature conditions.
Keywords: porous ZnO nanostructured thin films; room temperature gas sensor; surface photovoltage effect.