OCCUPIED AND UNOCCUPIED SURFACE-STATES ON THE SI(111) ROOT 3 X ROOT 3-B SURFACE

The Si(111) square-root 3 x square-root 3:BR 30-degrees surface has been studied with k-resolved inverse photoemission and angle-resolved photoemission. In the unoccupied region of the band structure, one strongly dispersing surface state is observed and in the occupied region, three surface states are observed. The unoccupied surface state is identified as an empty dangling-bond state and two of the occupied surface states are identified as backbond states of the adatom. The third occupied surface state, not observed on any other Si(111) square-root 3 x square-root 3:group-III surfaces, is found to be connected with boron bonded beneath the surface top layer. The experimentally observed energy dispersions are compared with published band-structure calculations.