The influence of interfaces and interlayers on the gas sensitivity in work function type sensors

It is known that barium carbonate can act as CO2 sensitive material in work function type gas sensors in ambient condition. The reaction is due to the formation of bicarbonate species at the surface. The cross-sensitivity to other acidic gases as NO2 was up to now regarded and described in terms of similar reactions on the carbonate surface. In this work it was found that the NO2 sensitivity is due to reactions on the back metalisation of the carbonate film. Using different layer systems different sensitivities can therefore be switched on and off according to the needs in special applications. The design of specialised sensor systems is possible on the base of the results found in this work. (C) 2003 Elsevier B.V. All rights reserved.