The influence of Rh surface doping on anomalous properties of thick-film SnO2 gas sensors

Here there are presented new results from the investigations of SnO2 thick-film sensor. The effects of rhodium surface doping on dc and ac properties of SnO2 gas sensors were studied. The measurements reveal anomalous behaviour of the sensors. Below characteristic temperature, the resistance of the sensors increases in presence of reducting gases. The mechanism associated with the presence of rhodium can be connected with the increase of acceptor surface states concentration and causes the inversion of near-surface layers.