Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 117: Graphene: Intercalation (jointly with O, HL)
TT 117.4: Vortrag
Freitag, 20. März 2015, 11:15–11:30, MA 041
Investigation of the electrostatic changes induced by metal islands on graphene/SiC(0001) using field-emission resonance spectroscopy with STM — •Anastasia Sokolova1, Alexander Stöhr2, Stiven Forti2, Ulrich Starke1,2, and M.Alexander Schneider1 — 1Solid State Physics, Friedrich-Alexander-University Erlangen-Nuremberg, Germany — 2Max Planck Institute for Solid State Research, Stuttgart, Germany
Using the Scanning Tunneling Microscope in field-emission resonance spectroscopy mode (FRS-STM) it is possible to map changes of the electrostatic potential in front of the graphene surface at the nanoscale [1]. We investigated the properties of 10 nm-sized metal islands on top of epitaxial graphene on SiC(0001) as well as islands intercalated underneath the graphene layer.
For cobalt and palladium islands on top of graphene we observe a spatially localized shift of the 1st field-emission resonance to higher energy strictly occurring at the topographical step. This is consistent with larger work functions of the metals with respect to that of graphene. In the case of intercalated cobalt islands FRS-STM shows a rise of the 1st field-emission resonance energy of only 150 meV and a spatially delocalized transition. Considering the properties of graphene flakes on an extended Co(0001) surface [2] this suggests negative charge of the capping graphene layer and a positive charge on the cobalt island.
[1] S. Bose et al 2010 New Journal of Physics 12 023028
[2] D. Eom et al 2009 Nano Letters 9 2844-2848