Understanding the STM images of epitaxial graphene on a reconstructed 6H-SiC(0001) surface: the role of tip-induced mechanical distortion of graphene
| Autor: | Thoyer, François, Lubin, Christophe, Cousty, Jacques, Morán-Meza, José A. |
|---|---|
| Přispěvatelé: | Laboratoire Nano-Magnétisme et Oxydes (LNO), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire d'Electronique et nanoPhotonique Organique (LEPO), Laboratoire d'Etude des NanoStructures et Imagerie de Surface (LENSIS), J.-A.M.M. would also like to acknowledge financial support from Réseau Thématique de Recherche Avancée(RTRA-Triangle de la Physique) and CEA/Direction des Relations Internationales (DRI)., jacques.cousty@cea.fr |
| Rok vydání: | 2016 |
| Předmět: |
Microscope
Materials science Scanning Tunneling Microscopy (STM) General Physics and Astronomy Atomic Force Microscopy (AFM) Silicon carbide 02 engineering and technology 01 natural sciences Molecular physics law.invention chemistry.chemical_compound Optics law Lattice (order) 0103 physical sciences Hexagonal lattice Physical and Theoretical Chemistry 010306 general physics [PHYS]Physics [physics] Local density of states Mechanical distortion business.industry Graphene 021001 nanoscience & nanotechnology Epitaxial graphene chemistry Density functional theory Scanning tunneling microscope 0210 nano-technology business |
| Zdroj: | Physical Chemistry Chemical Physics Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2016, 18, pp.14264. ⟨10.1039/C5CP07571H⟩ Physical Chemistry Chemical Physics, 2016, 18, pp.14264. ⟨10.1039/C5CP07571H⟩ Universidad Nacional de Ingeniería Repositorio Institucional-UNI UNI-Tesis instacron:UNI |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/c5cp07571h |
| Popis: | International audience; Epitaxial graphene (EG) grown on an annealed 6H-SiC(0001) surface has been studied under ultra-high vacuum (UHV) conditions by using a combined dynamic-scanning tunneling microscope/frequency modulation-atomic force microscope (dynamic-STM/FM-AFM) platform based on a qPlus probe. STM and AFM images independently recorded present the same hexagonal lattice of bumps with a 1.9 nm lattice period, which agrees with density functional theory (DFT) calculations and experimental results previously reported, attributed to the (6 x 6) quasi-cell associated with the 6H-SiC(0001) (6$\sqrt 3$x6$\sqrt 3$) R30 reconstruction. However, topographic bumps in AFM images and maxima in the simultaneously recorded mean-tunneling-current map do not overlap but appear to be spaced typically by about 1 nm along the [11] direction of the (6 x 6) quasi-cell. A similar shift is observed between the position of maxima in dynamic-STM images and those in the simultaneously recorded frequency shift map. The origin of these shifts is discussed in terms of electronic coupling variations between the local density of states (LDOS) of EG and the LDOS of the buffer layer amplified by mechanical distortions of EG induced by the STM or AFM tip. Therefore, a constant current STM image of EG on a reconstructed 6H-SiC(0001) surface does not reproduce its real topography but corresponds to the measured LDOS modulations, which depend on the variable tip-induced graphene distortion within the (6 x 6) quasi-cell. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|