Spatially resolved Raman spectroscopy of single- and few-layer graphene.
We present Raman spectroscopy measurements on single- and few-layer graphene flakes. By using a scanning confocal approach, we collect spectral data with spatial resolution, which allows us to directly compare Raman images with scanning force micrographs. Single-layer graphene can be distinguished from double- and few-layer by the width of the D' line: the single peak for single-layer graphene splits into different peaks for the double-layer. These findings are explained using the double-resonant Raman model based on ab initio calculations of the electronic structure and of the phonon dispersion. We investigate the D line intensity and find no defects within the flake. A finite D line response originating from the edges can be attributed either to defects or to the breakdown of translational symmetry.
Graf
D
D
Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland. grafdavy@phys.ethz.ch
Molitor
F
F
Ensslin
K
K
Stampfer
C
C
Jungen
A
A
Hierold
C
C
Wirtz
L
L