Epitaxial graphene Claire Berger GATECH- School of Physics, Atlanta CNRS-Institut Néel, Grenoble NIRT Nanopatterned Epitaxial graphite

Motivation : Carbon nanotube transistors

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

EFEF 1D metallic sub-bands Semiconducting Ntube Nanotube Electronic Structure

Band structure of graphene Linear dispersion Symmetry electrons - holes Pseudospin Chirality T. Ando, J. Phys. Soc. Jpn 67 (1998) 2857

Graphene ribbons Metallic ribbons Semiconducting or metallic ribbons Graphene ribbons should retain the essential properties of carbon nanotubes

M. Y. Han, B. Özyilmaz, Y. Zhang, P. Kim, Cond. Mat 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*)

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, (2004) Si C Graphene on SiC SiC (0001) Si-face (0001) C-face By controling temperature, growth of 1 to ~100 graphene layers