The Influence of Pt Doping on the Sensing and Conduction Mechanism of SnO2 Based Thick Film Sensors

The conduction mechanism in polycrystalline Pt doped SnO2 thick films is investigated by means of simultaneous DC and work function changes measurements under exposure to reducing gases (CO and H2) in different oxygen backgrounds. The results are showing that, in contrast to the case of polycrystalline undoped SnO2 thick films - where a continuous switch of the conduction mechanism from a depletion layer controlled model to an accumulation layer one was observed - the situation in case of Pt doping is different: one records an abrupt change in both resistance and work function changes, which may indicate the onset of the reduction of the material. The reduction of the material was further studied by a combination of DC resistance and catalytic conversion measurements.