STRUCTURE AND SURFACE CORE-LEVEL SHIFTS OF THE GAAS(114)A AND GAAS(114)B SURFACES

The structure and electronic properties of the high-index MBE-prepared GaAs(114)A and B surfaces were investigated in-situ by low-energy ele ctron diffraction and surface core-level spectroscopy. Under MBE condi tions both (114) surfaces show a c(2 X 2) reconstruction. We discuss t hree models for the c(2 X 2), which are designated as alpha, beta 1, a nd beta 2 structure analogous to the three models of the GaAs(001)-(2 x 4) reconstruction [1-3]. The surface care-level shift analysis of th e A-side yields two surface components for the As 3d peak (0.64 eV and -0.55 eV) as well as for the Ga 3d peak (0.42 eV and -0.40 eV). The G a 3d surface core-level components are only in agreement with the alph a model, which contains As-dimers and Ga-Ga-bonds on (001) terraces an d (111)A steps. The GaAs((114) over bar)B surface is less ordered but exhibits quite similar surface core level shifts. (C) 1998 Elsevier Sc ience B.V.