title: Raman spectroscopy as probe of nanometre-scale strain variations in graphene.
abstract: Confocal Raman spectroscopy has emerged as a major, versatile workhorse for the non-invasive characterization of graphene. Although it is successfully used to determine the number of layers, the quality of edges, and the effects of strain, doping and disorder, the nature of the experimentally observed broadening of the most prominent Raman 2D line has remained unclear. Here we show that the observed 2D line width contains valuable information on strain variations in graphene on length scales far below the laser spot size, that is, on the nanometre-scale. This finding is highly relevant as it has been shown recently that such nanometre-scaled strain variations limit the carrier mobility in high-quality graphene devices. Consequently, the 2D line width is a good and easily accessible quantity for classifying the crystalline quality, nanometre-scale flatness as well as local electronic properties of graphene, all important for future scientific and industrial applications.
authors.affiliation: JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.|Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Neumann
authors.affiliation: JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Reichardt
authors.affiliation: Instituto de Fsica, Universidade Federal Fluminense, Niterói, 24210-346 Rio de Janeiro, Brazil.
authors.forename: P
authors.initials: P
authors.lastname: Venezuela
authors.affiliation: JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Drögeler
authors.affiliation: JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Banszerus
authors.affiliation: JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schmitz
authors.affiliation: National Institute for Materials Science,1-1 Namiki, Tsukuba 305-0044, Japan.
authors.forename: K
authors.identifier: http://orcid.org/0000-0003-3701-8119
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: National Institute for Materials Science,1-1 Namiki, Tsukuba 305-0044, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Taniguchi
authors.affiliation: IMPMC, UMR CNRS 7590, Sorbonne Universités-UPMC Univ. Paris 06, MNHN, IRD, 4 Place Jussieu, Paris 75005, France.
authors.forename: F
authors.initials: F
authors.lastname: Mauri
authors.affiliation: JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Beschoten
authors.affiliation: JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.|Department of Physics and Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
authors.forename: S V
authors.initials: SV
authors.lastname: Rotkin
authors.affiliation: JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.|Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Stampfer