Electronic Switching of Single Silicon Atoms by Molecular Field Effects

We have observed on−off switching of scanning tunneling microscope current flow to silicon adatoms of the Si(111)-(7 × 7) surface that are enclosed within a bistable dimeric corral of self-assembled chlorododecane molecules. These thermally activated oscillations amounted to an order of magnitude change in the current. Theory showed that small changes in molecular configuration could cause alterations in the corralled adatom's electronic energy by as much as 1 eV due to local field effects, accounting for the observed current switching.