FLUX DEPENDENCE OF IN-SITU ELECTRON-TRANSPORT IN AG/SI(111)

Electrical transport in ultrathin films of Ag on the Si(111)-7×7 surface has been studied as a function of the incident flux rate in situ at room temperature with a four-probe technique. The origin of conduction in this system is unclear: two dimensional transport after the formation of a percolating cluster or conduction through the substrate via electrons transferred from the film to the substrate has been suggested as possible mechanisms. The four-probe voltage vs deposition time traces obtained at different flux rates collapse into a universal curve that supports conduction through the substrate and not through the film. The film morphology is expected to be smoother at lower flux rates so a steeper drop with time should have been observed if conduction were through the film. No significant dependence on the initial roughness of the clean surface is observed, which further supports conduction controlled by the substrate electronic structure. © 1995, American Vacuum Society. All rights reserved.