Observation and low-energy-electron-diffraction structure analysis of the Ge(111)-(√3 × √3 )R30°-Bi system

Surface reconstruction of the submonolayer Bi/Ge(111) system was investigated by low-energy diffraction and Auger-electron spectroscopy. It was found that an ordered (√3 × √3 ) superstructure is formed at ∼1/3 monolayer Bi deposition on the ∼320 °C surface. The data were analyzed by full dynamical low-energy-electron-diffraction calculations. A quantitative comparison between experiment and calculated I-V spectra suggests that the Bi adatoms are located at the ${\mathit{T}}_4$ site 1.324 Å above the first Ge layer. Our results imply that substrate atoms in the first two atomic layers are significantly displaced from their ideal bulk positions. Details of the atomic coordinates are given.