Study of Co-adsorption and atomic transport phenomena in the aged thin Pd layers

The responses of MIS gas sensors with Pd gate to the action of gas mixtures are experimentally studied. Computer modelling of the processes was undert aken, to disclose the peculiarities of co-adsorption of molecules on the re al surface of Pd films.': To understand the processes responsible for aging the sensors with Pd films aged by different methods were considered. The e ffect of the promoted dissociative adsorption of hydrogen on aged surface i n moist ambient has been-revealed. The pronounced selectivity of aged senso r with respect to hydrogen and moisture was also observed and explained. Th e modelling has allowed us to specify some scenarios for adsorption and sur face reactions. In particular, the coexistence of both atomic and molecular transport through the aged Pd gate has been found. Besides, simultaneous t wo- and one-center H-2 room temperature adsorption on the external surface of the aged layer has been observed.