First-principles investigation of location and electronic structure of adsorbed halogen atoms on semiconductor surfaces

Self-consistent-field Hartree-Fock investigations have been carried out for clusters representative of chlorine atoms adsorbed on a silicon surface and for the Si${\mathrm{H}}_3$Cl molecule, leading to a Si-Cl distance of 2.07 Å for the chemisorbed system, close to the Si-Cl distance of 2.06 Å obtained for the molecule, in good agreement with results of recent surface-extended x-ray fine-structure measurements. The density-of-states curve obtained for the cluster satisfactorily reproduces the observed ultraviolet photoelectron spectral peaks.