Atomic and chemical resolution in scanning force microscopy on ionic surfaces

Abstract

We present the results of theoretical modelling concerning the possibility to obtain atomic and chemical resolution in contact and non-contact mode Scanning Force Microscopy (SFM) and discuss a related issue of a working model for interpretation of SFM images. As a prototype system we consider the interactions of hard oxide tips with softer alkali halide surfaces in UHV. We briefly review the results of the molecular dynamics (MD) modelling of contact SFM and test some of the assumptions of intuitive SFM models. Then we illustrate the shortcomings of contact SFM by considering an image of a point defect. The mechanism of resolution in non-contact SFM and the effect of avalanche tip–surface adhesion are discussed next. A model image of an impurity defect in non-contact SFM is presented. Finally, the status of SFM with atomic resolution is discussed.