Stability and oxidation of the sandwich type gas sensors based on thin metal films

The stability of the properties is investigated in the new family of the solid-state gas sensors based on various thin metal films (Pt, Au, Ni, Mo) with the modifying top layer of tin oxide. The resistance response to exposure to gas is demonstrated being stable within certain interval of temperatures. The limits of the interval depend on the metal selected for the basic layer. The variation of the chemical composition is also studied in the sensors after overheating in the clean or contaminated air. The drift of the electric resistance and the mechanism of gas sensitivity are discussed on the basis of the oxidation of the metal film.