Strain and Charge in Epitaxial Graphene on Silicon Carbide Studied by Raman Spectroscopy
The phonon frequencies of epitaxial graphene on silicon carbide (SiC) depend on mechanical strain and charge transfer from the substrate to the epitaxial layer. Strain and doping depend on the preparation process and on the number of graphene layers. We measured the phonon frequencies by Raman spectroscopy and compare the results between epitaxial layers fabricated by high temperature annealing and by hydrogen intercalation of the covalently bound graphene layer of the 6 p 3 6 p 3 reconstructed SiC surface. Only the latter graphene layer shows tensile strain, which can partly be explained by lattice mismatch between substrate and epitaxial graphene.
Anton J. Bauer, Peter Friedrichs, Michael Krieger, Gerhard Pensl, Roland Rupp and Thomas Seyller
J. Röhrl et al., "Strain and Charge in Epitaxial Graphene on Silicon Carbide Studied by Raman Spectroscopy", Materials Science Forum, Vols. 645-648, pp. 603-606, 2010