First-principles simulation of atomic force microscopy image formation on a GaAs(110) surface: Effect of tip morphology

Ab initio pseudopotential fetal-energy techniques are used to simulate the image formation in atomic force microscopy on GaAs(110) surface. The effect of tip morphology on the image contrast is investigated by considering three different tip apexes on a Si tip: (1) the Si apex with a half-filled dangling bond; (2) the Ga apex with an empty dangling bond; and (3) the As apex with a full-filled dangling bond. It is shown that the dangling-bond state of the tip apex has a significant effect on the image contrast: the Ga apex will image the As sublattice, but reversely, the As apex will image the Ga sublattice, and in the case of the Si apex, it is possible to image only the As sublattice or both the As and Ga sublattices, depending on the tip-sample separation.