STM simulation of high aspect ratio tunneling behavior on the example of in situ harvested GaAs nanowire

Abstract

Usually, for general scanning tunneling microscopy (STM) investigations the actual tip shape is negligible beyond the assumption of being reasonable sharp and the investigated topological differences are small in comparison with the tip. This assumptions does no longer hold true, as soon as the size of the investigated structures get into the regime of the tip apex diameter. In this presentation, we show how through simulation of the physics of the tip-sample-system, we can explain the non trivial influence of the tip shape on a single STM scan line. Thus, we were able to reproduce STM measurements taken on GaAs nanowires with a diameter of 90 nm, using this simulation. The simulation results can further be generalized to other scanning probe techniques.