Bi on the Si(001) surface

The energetics and diffusion of Bi atoms on the Si(001) surface have been studied with density functional theory (DFT) to determine preferential adsorption sites. At several sites there is an unpaired electron on the Bi atom. Diffusion along the dimer rows at 300 K is very fast (${10}^{6}$ to ${10}^{11}\phantom{\rule{4.pt}{0ex}}{\text{s}}^{\ensuremath{-}1}$), with diffusion between rows considerably less so ($10\phantom{\rule{4.pt}{0ex}}{\text{s}}^{\ensuremath{-}1}$). Multiple adatoms were found to react to form ad-dimers, in agreement with previous results.