Electronic structure of the Si(111)√3 × √3 surface with column V adatoms

Theoretical studies using energy band calculations are performed for the milk-stool adsorption model recently presented for column V adatoms with √3 × √3 superlattice structure on the Si(111) surface. Calculations are performed for arsenic adatoms in the standard scheme with the local density functional and pseudopotential formalism. The obtained electronic structure may be well understood in the bond picture with sp3-like orbitals of the adatoms, and is in qualitative agreement with spectroscopic data. Total energy calculations are also performed, and this adsorption structure is found to be more stable by 2.00 eV per adatom than the monatomic adsorption at the threefold hollow site on this surface. Similar studies are then repeated for the system with column III adatoms. The stability of the milk-stool structure is not obtained in this case, in agreement with the existing studies of structure analysis experiments.