Raman mapping of a single-layer to double-layer graphene transition
Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland
2 Micro and Nanosystems, ETH Zurich, 8092 Zurich, Switzerland
3 Institute for Electronics, Microelectronics, and Nanotechnology (IEMN), CNRS-UMR 8520, BP. 60069, 59652 Villeneuve d'Ascq Cedex, France
Corresponding author: email@example.com
We report on confocal Raman spectroscopy on a few-layer graphene flake. Adjacent single- and double-layer graphene sections allow mapping the transition in vibrational and electronic properties to a second stacked graphene sheet and with it a weak interlayer coupling. Most prominently the width of the D' peak doubles upon going from a single to a double layer, which can be explained within the double-resonant Raman model. The intensities of the G and G' lines decrease at the crossover to a single layer. Contrary to the G' line the G peak position shifts to higher wave numbers, however, not uniformly over the entire section: its frequency fluctuates spatially. The Raman map of the D line intensity shows a non-zero contribution at the boundaries of the flake and the individual sections, which can be attributed either to defects and disorder or to the breakdown of translational symmetry, whereas within the flake no D line signal is detected.
© EDP Sciences, Springer-Verlag, 2007