Simultaneous imaging of the In and As sublattice on InAs 110/- 1=1/with dynamic scanning force microscopy

Distance-dependent dynamic scanning force microscopy SFM.measurements of InAs 110.- 1=1.acquired in ultrahigh vacuum at low temperatures are presented. On this surface, the atoms of the As sublattice are lifted by 80 pm with respect to the In sublattice and terminate the surface. Thus, since in most dynamic SFM images only protrusions with the periodicity of one sublattice are observed, these protrusions are correlated with the positions of the As atoms. However, under certain conditions, an additional contrast is visible which can be attributed to an interaction between the foremost tip atoms and the In atoms. Possible contrast mechanisms are discussed in terms of tip–sample distance and tip structure. q1999 Elsevier Science B.V. All rights reserved