THE VALENCE-BAND STRUCTURE OF THE ZNSE (001)-(2X1) SURFACE AS DETERMINED BY ANGLE-RESOLVED PHOTOEMISSION SPECTROSCOPY

The valence band structure of the (2x1) reconstructed surface of ZnSe{ 001} has been investigated using angle-resolved photoemission spectros copy. The results of our analysis are consistent with the band structu re of a previously proposed (2x1) Se dimer-terminated surface and show ed that there may be three surface resonance states lying in the first 3 eV from the top of the valence band maximum which extend over most of the length of the Brillouin zone along the [110] direction. A fourt h feature identified as a surface state was observed around the (X) ov er bar point at similar to -5.8 eV. The gap surface state previously p redicted for the Se dimer-terminated surface was barely resolvable and was found to lie just above the valence band maximum at the <(Gamma)o ver bar> point.