The crystallographic symmetries and spatial distribution of stacking domains in graphene films on SiC have been studied by low energy electron diffraction (LEED) and dark field imaging in a low energy electron microscope (LEEM). We find that the graphene diffraction spots from 2 and 3 atomic layers of graphene have 3-fold symmetry consistent with AB (Bernal) stacking of the layers. On the contrary, graphene diffraction spots from the buffer layer and monolayer graphene have apparent 6-fold symmetry, although the 3-fold nature of the satellite spots indicates a more complex periodicity in the graphene sheets.
@article{arxiv.1107.0085,
title = {Three-Fold Diffraction Symmetry in Epitaxial Graphene and the SiC Substrate},
author = {David A. Siegel and Shuyun Zhou and Farid El Gabaly and Andreas K. Schmid and Kevin F. McCarty and Alessandra Lanzara},
journal= {arXiv preprint arXiv:1107.0085},
year = {2011}
}
Comments
An addendum has been added for the arXiv version only, including one figure with five panels. Published paper can be found at http://link.aps.org/doi/10.1103/PhysRevB.80.241407