The response of palladium metal-insulator-semiconductor devices to hydrogen-oxygen mixtures: comparisons between kinetic models and experiment

The operation of hydrogen-sensitive metal-insulator-semiconductor (MIS) devices in the presence of oxygen is described using a detailed model of the surface and interface kinetics. The solution methods developed here build on existing models by considering adsorbed oxygenated species in the interaction between atomic hydrogen at the metal-semiconductor interface and the external surface. The net effect of the adsorbed oxygenated species is to increase the amount of interfacial hydrogen predicted to exist within the structure at equilibrium. These theoretical predictions are compared to computed results from a previously existing model; furthermore, both mechanistic models are analyzed in light of new and previously published experimental response trends for MIS devices. Although the two models considered in this work are each found to be useful in understanding some aspects of the response, elementary reaction mechanisms appear to be inadequate for prediction of response curves. The results of these comparisons suggest that the kinetics for operation of MIS sensors in hydrogen-oxygen mixtures are quite complex, and may be strongly morphology-dependent. Published by Elsevier B.V.