Large Variations of the Raman Signal in the Spectra of Twisted Bilayer Graphene on a BN Substrate

0384496 - ÚFCH JH 2013 RIV US eng J - Journal Article
Kalbáč, Martin - Frank, Otakar - Kong, J. - Sanchez-Yamagishi, J. - Watanabe, K. - Taniguchi, T. - Jarillo-Herrero, P. - Dresselhaus, M. S.
Large Variations of the Raman Signal in the Spectra of Twisted Bilayer Graphene on a BN Substrate.
Journal of Physical Chemistry Letters. Roč. 3, č. 6 (2012), s. 796-799. ISSN 1948-7185
R&D Projects: GA AV ČR IAA400400911; GA AV ČR IAA400400804; GA MŠMT ME09060; GA ČR GAP204/10/1677
Institutional support: RVO:61388955
Keywords : nanomaterials * nanoparticles * nanostructures
Subject RIV: CG - Electrochemistry
Impact factor: 6.585, year: 2012

We report an unusual enhancement of the Raman signal of the G mode in a twisted graphene bilayer (2-LG) on a hexagonal single-crystalline boron nitride substrate. We used an isotopically engineered 2-LG, where the top layer was composed of C-13 atoms and the bottom layer of C-12 atoms. Consequently, it was possible by Raman spectroscopy to distinguish between the enhancement coming from the top and bottom layers. The enhancement of the G mode was, however, found to be similar for the top and bottom layers, and this enhancement effect was observed only at certain locations on the substrate. The experiment with two different laser excitation energies showed that the location of the enhanced spots is dependent on the laser excitation energy. Therefore our results suggest that the enhancement comes from new states in the electronic structure, which are a consequence of a local specific rotation of the grains in graphene layers.
Permanent Link: http://hdl.handle.net/11104/0214123