Unoccupied surface-state band on Si(111) 1×1-Ge

Angle-resolved inverse photoemission studies of the Si(111) 1×1-Ge surface reveal an unoccupied surface-state band induced by the germanium overlayer. The band exhibits very little energy dispersion along the major symmetry directions of the surface Brillouin zone. The results are explained in terms of a disordered Si(111) 2×1-Ge surface. © 1988 The American Physical Society.