Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 47: Electronic Structure of Surfaces: Spectroscopy, Surface States

O 47.2: Poster

Dienstag, 8. März 2016, 18:15–20:30, Poster E

Local Tunneling Decay Length and Kelvin Probe Force Spectroscopy — •Florian Albrecht¹, Martin Fleischmann², Manfred Scheer², Leo Gross³, and Jascha Repp¹ — ¹Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany — ²Institute of Inorganic Chemistry, University of Regensburg, 93053 Regensburg, Germany — ³IBM Research - Zurich, 8803 Rüschlikon, Switzerland

Current-distance spectroscopy has been widely applied to determine variations of the work function at surfaces. While for homogeneous sample areas this technique is commonly accepted to yield at least qualitative results, its applicability to atomic-scale variations has not been proven neither right nor wrong. Here we benchmark current-distance decay constant measurements against the well established Kelvin probe force spectroscopy method for distinctly different cases with atomic-scale variations of the local contact potential. Whereas the maps of the current-distance decay constant are consistent with being topographical artifacts, the Kelvin probe force spectroscopy maps show variations of the local contact potential difference in agreement with expected surface dipoles. This comparison clarifies that maps of the current-distance decay constant are not suited to directly characterize contact potential variations at surfaces on atomic length scales.