GAS-INDUCED RESISTANCE RESPONSE IN ULTRA-THIN METAL-FILMS COVERED WITH NONCONDUCTIVE LAYERS

Conductive type gas sensitive sandwiches consisting of two or three la yers are produced and investigated in the present work. The sandwiches studied are based on the ultra-thin metal bottom-layer of Pt, Au or N i. It is demonstrated that the metal oxide top-layer makes the sandwic h highly sensitive to gas even in the case of fully insensitive single bottom-layer. Selectivity of the sandwich is modified significantly b y the choice of the metal for the bottom-layer and the adding of the u ltra-thin metal inter-layer. The thickness of the bottom-layer could b e optimised for achieving the best sensitivity to gases. The stability of the sandwiches in the temperature ranges depends on the selected b ottom-metal. (C) 1997 Elsevier Science S.A.