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Epitaxial graphene Claire Berger GATECH- School of Physics, Atlanta CNRS-Institut Néel, Grenoble NIRT Nanopatterned Epitaxial graphite
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Motivation : Carbon nanotube transistors
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Motivation : Multiwalled carbon nanotubes are ballistic conductors at room temperature T. Ando, T. Nakanishi and R. Saito J. Phys. Soc. Jpn. 67, 2857 (1998) “ The absence of backward scattering is shown to be ascribed to Berry's phase which corresponds to a sign change of the wave function under a rotation of a neutrino-like particle* in the wave vector space in a two-dimensional graphite ” *i.e obeying the Dirac-Weyl equation Quantized ballistic conductance Nanotube fiber - L (µm) G (2e 2 /h) L V
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EFEF 1D metallic sub-bands Semiconducting Ntube Nanotube Electronic Structure
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Band structure of graphene Linear dispersion Symmetry electrons - holes Pseudospin Chirality T. Ando, J. Phys. Soc. Jpn 67 (1998) 2857
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Graphene ribbons Metallic ribbons Semiconducting or metallic ribbons Graphene ribbons should retain the essential properties of carbon nanotubes
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M. Y. Han, B. Özyilmaz, Y. Zhang, P. Kim, Cond. Mat. 0702511 E =0.2 eV.nm W *=16 nm Energy gap in exfoliated graphene ribbons from Philip Kim, Columbia University Gap E g = E W-W*)
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Thermal decomposition of SiC at high temperature (~1400 o C) - high vacuum after surface flattening by hydrogen etching Epitaxial growth of graphene layers on 4H-SiC graphite SiC LEED 3 graphene layers A.Charrier et al., J. Applied Physics 92, 2479 (2002) C. Berger et al., Journal of Physical Chemistry B 108, 19912 (2004) Si C Graphene on SiC SiC (0001) Si-face (0001) C-face By controling temperature, growth of 1 to ~100 graphene layers
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