Chemistry Reference
In-Depth Information
Chapter 10
Electronic and Transport Properties of
Graphene Nanoribbons
Katsunori Wakabayashi
International Center for Materials Nanoarchitectonics (MANA),
National Institute for Materials Science (NIMS),
Namiki 1-1, Tsukuba 305-0044, Japan
ka.wakaba@gmail.com
Low-energy electronic states of graphene are described by the massless
Dirac Fermions. In nano-graphene, however, this description is strongly
modified due to the existence of edges. In this chapter, we discuss
the electronic transport properties of graphene nanoribbons, and clarify
the role of edge boundary condition. Here we show that the graphene
nanoribbons with zigzag edges subjected to the long-ranged impurities
provide on-perfectly conducting channel, i.e. the absence of Anderson
localization, because in each valley the balance between left- and right-
going modes is violated due to the central subband originating from the
edge states. We also study the electron transport through the graphene
junction structures, where the zero-conductance anti-resonances is
observed.
1. Introduction
Recently graphene, a single-layer hexagonal lattice of carbon atoms, has
emerged as a fascinating system for fundamental studies in condensed mat-
ter physics, as well as the promising candidate material for future appli-
cation in nanoelectronics and molecular devices.
1
The honeycomb crystal
structure of single layer graphene consists of two nonequivalent sublattices
and results in a unique band structure for the itinerant
-electrons near the
Fermi energy which behave as massless Dirac Fermion. The valence and
conduction bands touch conically at two nonequivalent Dirac points, called
K
+
and
π
K
−
point, which form a time-reversed pair, i.e. opposite chiral-
ity. The chirality and a Berry phase of
at the two Dirac points provide
an environment for highly unconventional and fascinating two-dimensional
π
167
