Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 50: Organic semiconductors
HL 50.11: Vortrag
Mittwoch, 13. März 2013, 12:15–12:30, H13
using STM/nc-AFM to discriminate adsorbed molecules and attachment geometries on Si(111)-7x7 — •Zsolt Majzik1, Benedict Drevniok2, Wojciech Kaminski3, Martin Ondráček1, Alastair B. McLean2, and Pavel Jelínek1 — 1Institute of Physics, Academy of Science of the Czech Republic, Cukrovarnicka 10, 162 53, Prague, Czech Republic — 2Queen*s University, Kingston, Ontario, Canada, K7L 3N6. — 3University of Wroczaw, plac Maksa Borna 9, 50-204 Wroczaw, Poland
Scanning tunneling microscopy (STM) has been used to study surface reactions leading to an improved understanding of surface chemistry at the atomic length scale. However, by using a qPlus sensor, non-contact atomic force microscopy (nc-AFM) can be performed at the same time, allowing simultaneous measurement of the tip-surface conductance and tip-surface interaction. Here we present a joined experimental and theoretical study of the adsorption of hydrogen, ethylene and benzene on the Si(111)-7x7. Based on force site spectroscopy combined with density functional theory (DFT) simulations we found that over the molecules and hydrogen only a very weak attractive force appear and mainly the repulsive interaction acts along tip approach. The position of the attractive force maxima on the Z scale and the magnitude of the attractive force can be well used as a fingerprint to discriminate between common defects, such as vacancies, and adsorbates. Moreover, using benzene and ethylene as model systems, we demonstrate that combined STM/AFM provides more information about attachment geometries than STM alone.