ON THE STRUCTURE AND ELECTRONIC-PROPERTIES OF THE GAAS(11(3)OVER-BAR)-B SURFACE

GaAs(113BAR)B surfaces were prepared by ion bombardment and annealing (IBA) and by molecular beam epitaxy (MBE) using a single Knudsen cell filled with GaAs. These surfaces were investigated through low-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and ang le-resolved UV photoelectron spectroscopy (ARUPS) using photon energie s of hv = 11.8 and 21.2 eV and synchrotron light. With both IBA and MB E, a 1 x 1 reconstructed surface was prepared which differs by a large amount of As in the surface layer. For the MBE 1 x 1 reconstructed su rface, three different surface states or resonances were found at +0.3 , -0.7 and -3.5 eV with respect to the valence band maximum which are assigned to As-derived dangling bonds and back bonds. The states at +0 .3 and -0.7 eV can be quenched by H adsorption. For the n-type sample the bands are bent upwards by 0.30 V at the surface.