Scanning force microscopy simulations of well-characterized nanostructures on dielectric and semiconducting substrates

A numerical method for simulating the interaction between a pyramidal tip and a surface with nanostructures is presented. The model takes into account both attractive van der Waals and repulsive forces with the help of a pairwise Lennard-Jones interaction potential. With this potential, the attractive van der Waals forces are only evaluated by using the dipolar interaction between the two interacting parts. It is shown that the sphere-plane model usually used to mimic a scanning force microscope (SFM) is not accurate enough. The major advantage of the present method is the possibility of simulating SFM images of well-defined objects with nanometer dimensions and arbitrary profile on a flat surface. We give an illustration of this method by making image simulations of two dots of silicon and silver on, respectively, Si and MgO substrates in the so called ‘constant distance mode’ of imaging.