Surface electronic and chemical structure of (1120)CdSe: Comparison with CdS

Surface photovoltage spectroscopy, Auger electron spectroscopy, LEED, X-ray and ultraviolet photoemission measurements are reported for (112̄0) CdSe under a variety of ultrahigh vacuum conditions. As with CdS, all surface electronic features can be related to chemical contamination, Ar⁺ bombardment-induced lattice defects, or bulk trap states. Oxygen adsorption on CdSe and CdS produce qualitatively different electronic features which are attributed to different bonding at surface vacancy sites. Changes in surface atomic order show no direct effect on measured electronic features. Furthermore, CdSe exhibits no intrinsic surface state features which can account for its Schottky barrier formation with metals.