STRUCTURAL AND ELECTRONIC-PROPERTIES OF SB ISLANDS ON GAAS (110)

We present the results of theoretical calculations of the electronic s tructure of the Sb/GaAs(110) interface in the submonolayer coverage re gime performed in the full ab initio self-consistent pseudopotential s cheme. Different structural models for the edges of the extended Sb is lands have been considered and their equilibrium geometry has been det ermined by total energy minimization. The single particle band structu re shows interface states arising mainly from the incomplete bonding o f the Sb adatoms at the terrace edge to the substrate, which fall with in the optical gap. Distinct features are associated to different isla nd terminations. The interface turns out to be metallic in all the con sidered cases with a partially occupied peak at the Fermi level. We ha ve also studied the effect of including explicitly the on-site Hubbard electron-electron correlation in the calculation of the quasiparticle spectrum, obtaining the observed semiconducting interface when the Co ulomb interaction parameter U is larger than 3 eV. The interface state s within the optical band gap can be present also at higher coverages when some disorder exists, evidentiating a general mechanism for the F ermi level pinning at this interface. (C) 1996 American Vacuum Society .