Ab initio study of the self-organised Bi-lines on the Si(0 0 1) surface

We have perfomed an ab initio theoretical study of the stability, atomic geometry and electronic structure of the self-organised Bi-lines on the Si(0 0 1) surface. Our results show that the Bi-lines are formed by Bi-dimers parallel to the surrounding Si-dimers, with a missing dimer row between the Bi-dimers. In contrast to a recently proposed model of symmetrically disposed surface Si-dimers (i.e. with no buckling), our total energy calculations indicate that the buckling of the Si-dimers is an exothermic process, reducing the surface total energy by 0.11 eV/dimer. Our theoretically simulated STM results suggest a low density of states close to the valence band maximum, localized on the Bi-lines, supporting a recently proposed model of quantum antiwire systems for Bi-lines on the Si(0 0 1) surface.