Quantitative Scanning Tunneling Microscopy at Atomic Resolution: Influence of Forces and Tip Configuration

Abstract

Atom resolved scanning tunneling microscopy images are known to depend on the nature of the tip and its interaction with the surface. We present a new method for determining barrier height and tip-surface interactions. For Cu(100) images, two distinct tip types are seen. At larger tunnel currents there is evidence for forces acting between tip and surface. We show that a molecular dynamics simulation of tip and surface is able to quantitatively explain the results, and gives a good estimate of both absolute tip-surface separation and the site dependent forces on individual atoms.