Bridging the pressure gap for palladium metal-insulator-semiconductor hydrogen sensors in oxygen containing environments

A comparison has been made between the steady state response obtained from palladium metal-insulator-semiconductor (Pd-MIS) structures exposed to hydrogen in presence of oxygen under atmospheric conditions and the response calculated from a model valid under ultrahigh vacuum conditions. It is shown that the model gives a good description of the steady state response as a function of hydrogen and oxygen pressure. This is of interest not only for the understanding of the sensing mechanism of Pd-MIS hydrogen sensors but would also imply that the used model for the water forming reaction on Pd gives realistic estimates for the hydrogen coverage on the Pd surface over a vast pressure range.