BIAS VOLTAGE-DEPENDENT SCANNING-TUNNELING-MICROSCOPY IMAGES OF A GAAS(110) SURFACE WITH SMALL AG CLUSTERS

We report bias voltage-dependent images of scanning tunneling microsco py taken on a GaAs(110) surface with small Ag clusters. The direction of the observed atom rows changes at certain negative and positive sam ple bias voltages (V-s). Such changes are attributed to the different atoms (Ga or As) in the case of V-s < 0 and to the different surface s tates of Ga in the case of V-s > 0. The images also show a change in c ontrast with the V-s. All of these results are explained by tip-induce d and surface charge-induced band bendings in addition to the fundamen tal surface states. (C) 1998 Elsevier Science B.V. All rights reserved .