Adsorption and Electrical Conduction in Thin Films

Changes in the electrical resistance of high-area, evaporated metal films after adsorption of gases have been attributed to a long-range effect of the adsorbed material. It is shown that the experimental findings do not demand this interpretation, and that contributions to the observed resistance increases may arise from any of the following: (1) A localized resistance change at necks in the film. (2) Changes in surface stress on adsorption. (3) A decrease in the rate of electron tunneling across gaps in the film with an increase in the work function. The last mechanism appears most likely, and experiments to establish these effects quantitatively are outlined.