Field-effect-induced gas sensitivity changes in metal oxides

Abstract The sensitivity of micromachined gas sensor elements with respect to CO, NO, NO 2 , CH 4 , H 2 O and oxygen partial pressure changes was investigated. The microsensors consisted of thin films of RGTO-SnO 2 deposited on top of resistively heated Si 3 N 4 membranes. The electrical insulation between the Pt heater and SnO 2 sensing layer circuits was provided by a thin dielectric layer. Applying a bias voltage across this layer, field-effect-induced changes in the gas sensing properties could be studied. We find that bias voltage changes can be used to systematically modify the cross-sensitivity of identically prepared sensor elements. These results are relevant for the realisation of monolithically integrated gas sensor arrays.