Scanning tunneling microscopy artifact and real structure: Steps of Ag(110)

¹ Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin, Germany
² Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany

Received: 6 May 1999
Accepted: 28 September 1999

Abstract

In STM (scanning tunneling microscopy) images of Ag(110) the step edges usually appear to have fringes parallel to the fast scanning direction. However, straight steps are stable at 300 K, which is revealed by the sharp edges observed in STM scans parallel to the steps, and gradually get rough at elevated temperatures. In combination with a realistic Monte Carlo model that for the first time simulates also the scanning process by introducing the STM tip in terms of a local disturbance of the diffusion, the details of the atomistic mechanisms of the fringe formation become clear. The fringes are an experimental artifact of the scanning tip, which in average pulls Ag atoms by one lattice distance out of otherwise straight steps. Comparison with our experiments reveals a tip/surface interaction energy of about 0.14 eV.