Angle-resolved photoemission study of the valence band structure of ZnO(10(1)over-bar0)

The valence band structure of the (10 (1) over bar0) surface of wurtzite ZnO has been investigated by angle-resolved photoelectron spectroscopy utilizing polarized synchrotron radiation. The energetic position and the dispersion width of the O2p dangling-bond (DB) state are determined along the high symmetry axes of the surface Brillouin zone (SBZ). The O2p.DB is 3.7 eV below the (Gamma) over bar point and disperses to higher binding energies with a total dispersion width of similar to 1.2 eV. Comparison with the projected bulk bands from the earlier theoretical studies reveals that the DB state is a surface resonance in the whole SBZ. Polarization dependent measurements have also been carried out along the (Gamma X') over bar axis suggest that the DB band with odd symmetry with respect to the mirror plane of the crystal surface has a larger dispersion than the band with even symmetry.