Surface Electrical Conduction Correlated with Surface Structures and Atom Dynamics

By utilizing a variety of surface super structures formed on silicon surfaces, we have clarified close correlations between the atomic-scale structures and surface-electrical-conduction phenomena. In paricular, we have succeeded for the first time in experimentally confirming the electrical conduction via surface-state bands that are inherent in the surface supertructures. Also, an important phenomenon has been found: atoms adsorbed on the surface donate carriers to the surface-state band, resulting in a remarkable enhancement of conductivity. The ultimate two-dimensional electron systems composed of surface-state bands, which are made close up in our study, are expected to provide a new stage insurface physics.