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Title: Direct transfer and Raman characterization of twisted graphene bilayer

Twisted bilayer graphene (tBLG) is constituted of a two-graphene layer with a mismatch angle θ between the two hexagonal structures. It has recently attracted much attention—thanks to its diverse electronic and optical properties. Here, we study the tBLG fabricated by the direct transfer of graphene monolayer prepared by chemical vapor deposition (CVD) onto another CVD graphene layer remaining attached to the copper foil. We show that high quality and homogeneous tBLG can be obtained by the direct transfer which prevents interface contamination. In this situation, the top graphene layer plays a supporting mechanical role to the bottom graphene layer as confirmed by optical microscopy, scanning electron microscopy, and Raman spectroscopy measurements. The effect of annealing tBLG was also investigated using micro-Raman spectroscopy. The Raman spectra exhibit a splitting of the G peak as well as a change in the 2D band shape indicating a possible decoupling of the two monolayers. We attribute these changes to the different interactions of the top and bottom layers with the substrate.
Authors:
 [1] ;  [2] ; ;  [3] ; ;  [1] ; ;  [4]
  1. Faculté des Sciences de Tunis, Université de Tunis El Manar, Campus Universitaire, 2092 El Manar Tunis (Tunisia)
  2. (France)
  3. GeePs, CNRS UMR8507, CentraleSupelec, Univ Paris-Sud, Sorbonne Universités-UPMC, Univ Paris 06, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette Cedex (France)
  4. CNRS/LPN, Route de Nozay, F-91460 Marcoussis (France)
Publication Date:
OSTI Identifier:
22395726
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 10; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; CHEMICAL VAPOR DEPOSITION; COPPER; DECOUPLING; FOILS; GRAPHENE; INTERFACES; LAYERS; OPTICAL MICROSCOPY; OPTICAL PROPERTIES; RAMAN SPECTRA; RAMAN SPECTROSCOPY; SCANNING ELECTRON MICROSCOPY; SUBSTRATES