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 microscopy taken on a GaAs 110.surface with small Ag clusters. The direction of the observed atom rows changes at certain negative and positive sample bias voltages Vs.. Such changes are attributed to the different atoms Ga or As.in the case of Vs-0 and to the different surface states of Ga in the case of Vs)0. The images also show a change in contrast with the Vs. All of these results are explained by tip-induced and surface charge-induced band bendings in addition to the fundamental surface states. q1998 Elsevier Science B.V. All rights reserved.