Tip-surface interactions in noncontact atomic force microscopy on reactivesurfaces

The imaging process in noncontact atomic force microscopy (AFM) is studied on a number of reactive surfaces, namely, the Takayanagi reconstructed Si(1 11), InP(110), and GaAs(110). We show that on these surfaces, the short-ran ge dangling-bond type of interaction between the tip and the surface is dec isive in achieving atomic resolution. The short-range tip-surface interacti on is modeled in the density functional theory within the GGA approximation , We show that we can achieve quantitative agreement with the experimental data in the commonly used frequency modulation technique for AFM surface co rrugation with a. very simple model for the tip geometry treating the tip-s urface interaction in the perturbation theory, The nature of the short-rang e tip-surface interaction on the three surfaces is considered and the conse quences thereof for the experiments is discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.