Existence probabilities of single Si atoms diffusing in Si(111)-(7 x 7) half-unit cells at room temperature

We determined the probabilities of finding diffusing Si atoms in faulted and unfaulted half-unit cells on the Si(111)-(7 x 7) surface. An adsorbed Si atom on the surface at room temperature moved in the half-unit cells. The atom was adsorbed via atom manipulation and located via under-sampled scanning tunneling microscopy. Images of the half-unit cells with the diffusing Si atom and images of the clean surface were superimposed via image processing to calculate differences used to determine the Si atom positions at room temperature. There were different probabilities for Si atom diffusion in faulted and unfaulted half-unit cells.