Surface states of ordered Au, Ag, and Cu overlayers on Si(111) studied by inverse photoemission

The 3× 3-Au, 3× 3-Ag, "5×5"-Cu, and 6×6-Au overlayer interfaces on Si(111) are studied with k-resolved inverse photoemission. Strong surface-state emission is observed at 2.0 eV above the Fermi level for all these surfaces, which is attributed to the local bonding between the metal atoms and the Si(111) substrate. The long-range order of the larger unit cells manifests itself as weak surface states at the Fermi level. © 1986 The American Physical Society.