GEOMETRIC AND ELECTRONIC-STRUCTURE OF MOLECULAR-BEAM EPITAXY-PREPAREDGAAS(112) AND GAAS(113) SURFACES

The surface structure and the electronic properties of the high-index molecular beam epitaxy (MBE)-prepared GaAs surfaces (112)A and B as we ll as (113)A and B were investigated in situ by low-energy electron di ffraction and surface core level spectroscopy. Under MBE conditions, b oth (112) surfaces are unstable. The (112)A surface consists of five k inds of facets with the orientations {110}, {124} and (111). The ((112 ) over bar)B surface forms four types of facets with the orientations ((111) over bar), ((113) over bar) and {(110) over bar}. The surface c ore-level shift analysis on GaAs(112)A yields surface components for t he As 3d peak (-0.31 eV) as well as for the Ga 3d peak (+0.28 eV). On GaAs(113)A both the (8x1) superstructure and the core-level analysis s upport a structure model proposed recently by Wassermeier et al. (Phys . Rev. B, 51 (1995) 14721). After MBE preparation, the ((113) over bar )B surface forms facets with the orientations {1(1) over bar0$} and (( 111) over bar). (C) 1997 Elsevier Science Ltd.