The (111)-(3 x 3)B R30º surface was studied by using k-resolved inverse photo-emission and angle-resolved photo-emission techniques. One strongly dispersive surface state was observed in the unoccupied region of the band structure, and 3 surface states were observed in the occupied region. The unoccupied surface state was found to be an empty dangling-bond state, and 2 of the occupied surface states were found to be back-bond states of the adatom. A third occupied surface state, which was not observed on any other (111)-(3 x 3)(group-III) surface, was found to be related to B which was bound beneath the top surface layer.

T.M.Grehk, P.Martensson, J.M.Nicholls: Physical Review B, 1992, 46[4], 2357-62