Cooperative effects and dipole formation at semiconductor and self-assembled-monolayer interfaces

Dipole formation processes at self-assembled monolayers of benzene derivatives chemisorbed on the Si(111) surface are investigated from first principles. The surface dipole is shown to be sensitive to the molecular coverage and dominated by intramolecular charge rearrangement due to long-range, cooperative behavior. This cooperative behavior suppresses substrate contributions to dipole formation.