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Dependence of the Raman spectrum characteristics on the number of layers and stacking orientation in few‐layer graphene
Author(s) -
Bayle Maxime,
Reckinger Nicolas,
Huntzinger JeanRoch,
Felten Alexandre,
Bakaraki Ahmad,
Landois Périne,
Colomer JeanFrançois,
Henrard Luc,
Zahab AhmedAzmi,
Sauvajol JeanLouis,
Paillet Matthieu
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201552204
Subject(s) - graphene , raman spectroscopy , stacking , materials science , chemical vapor deposition , exfoliation joint , layer (electronics) , g band , substrate (aquarium) , analytical chemistry (journal) , crystallography , nanotechnology , chemistry , optics , physics , oceanography , organic chemistry , chromatography , geology
Few‐layer graphene (FLG) samples prepared by two methods (chemical vapor deposition (CVD) followed by transfer onto SiO 2 /Si substrate and mechanical exfoliation) are characterized by combined optical contrast and micro‐Raman mapping experiments. We examine the behavior of the integrated intensity ratio of the 2D and G bands ( A 2D / A G ) and of the 2D band width ( Γ 2D ) as a function of the number of layers ( N ). For our mechanically exfoliated FLG, A 2D / A G decreases and Γ 2D increases with N as expected for commensurately stacked FLG. For CVD FLG, both similar and opposite behaviors are observed and are ascribed to different stacking orders. For small (respectively, large) relative rotation angle between consecutive layers ( θ ), the values of the A 2D / A G ratio is smaller (respectively, larger) and the 2D band is broader (respectively, narrower) than for single‐layer graphene. Moreover, the A 2D / A G ratio decreases (respectively, increases) and, conversely, Γ 2D increases (respectively, decreases) as a function of N for small (respectively, large) θ . An intermediate behavior has also been found and is interpreted as the presence of both small and large θ within the studied area. These results confirm that neither A 2D / A G nor Γ 2D are definitive criteria to identify single‐layer graphene, or to count N in FLG.