Selectivity in high-temperature operated semiconductor gas-sensors

High-temperature operated metal oxides like Ga2O3 developed in the last years show certain advantages like reproducibility and robustness resulting from a conduction mechanism which is independent on grain boundary effects. But similar to the lower temperature operated oxides like SnO2 and ZnO they also possess broad band sensitivity characteristics, i.e. they respond to all gases with similar chemical properties. This paper shows to which extent strategies to achieve selective gas detection with one single sensor are applicable with these metal oxides. Temperature variations, surface modifications and the use of physical and chemical filters directly attached to the sensor surface are discussed in this paper. (C) 1998 Elsevier Science S.A. All rights reserved.