Epitaxial graphene

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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
Multiwalled carbon nanotubes are ballistic
conductors at room temperature
- L (µm)
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
G (2e2/h)
Nanotube fiber
L
V
Quantized ballistic conductance

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Nanotube Electronic Structure
1D metallic sub-bands
Semiconducting Ntube
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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
Semiconducting or metallic ribbons
Metallic ribbons
Graphene ribbons should retain the essential
properties of carbon nanotubes
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Energy gap in exfoliated graphene ribbons
from Philip Kim, Columbia University
E 0.2 eV.nm
W16 nm
Gap Eg E /(W-W)
M. Y. Han, B. Özyilmaz, Y. Zhang, P. Kim, Cond.
Mat. 0702511
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Epitaxial growth of graphene layers on 4H-SiC
Thermal decomposition of SiC at high temperature
(1400oC) - high vacuum after surface flattening
by hydrogen etching
A.Charrier et al., J. Applied Physics 92, 2479
(2002)
LEED 3 graphene layers
By controling temperature, growth of 1 to 100
graphene layers
C. Berger et al., Journal of Physical Chemistry B
108, 19912 (2004)