Regensburg 2013 – wissenschaftliches Programm
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MI: Fachverband Mikrosonden
MI 10: Scanning Probe Microscopy
MI 10.3: Vortrag
Donnerstag, 14. März 2013, 10:00–10:15, H5
Chemical Resolution with nc-AFM in InSn Mixed Atomic Chains on Si(100) — Martin Setvín1,2, Pingo Mutombo1, •Martin Ondráček1, Zsolt Majzik1, Vladimír Cháb1, Ivan Ošťádal2, Pavel Sobotík2, and Pavel Jelínek1 — 1Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic — 2Faculty of Mathematics and Physics, Charles University in Prague, Prague, Czech Republic
Although scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are very successful in probing atomic and electronic structure of surfaces, achieving chemical sensitivity at the atomic level is still a challenge. Sugimoto et al. [Nature 466, 64 (2007)] demonstrated a method of single-atom chemical identification on a surface alloy of IV-group elements on Si(111) using a frequency modulation atomic force microscope (FM-AFM). In our present study, we combine room-temperature (RT) FM-AFM measurements with DFT simulations to explore atomic and chemical structure of heterogeneous atomic chains composed of III and IV-group atoms (In and Sn) grown on the Si(100) surface. These chains consist of dimers of either the same or different atomic species. We demonstrate that in contrast to STM, the FM-AFM technique is able to resolve individual atoms in such structures even at RT. We also show that chemical identification of single atoms is possible when the force-site spectroscopy is combined with DFT simulations. The unambiguous chemical identification could be achieved even though the force measured on top of a particular atom could strongly depend on the neighboring atoms in the chain.