Electronic properties of nanographene

Abstract

Graphene, a single-layer hexagonal lattice of carbon atoms, has emerged recently as a fascinating system for fundamental studies in condensed matter physics, as well as a promising candidate material for future applications in carbon-based nanoelectronics and molecular devices [1, 2]. Since the honeycomb crystal structure of graphene consists of two nonequivalent sublattices, graphene has a unique band structure for the itinerant p -electrons near the Fermi energy. In particular, as we have seen in Chapter 2, the motion of electrons in graphene near the Fermi energy is well described by the massless Dirac equation. The valence and conduction bands conically touch at two nonequivalent Dirac points, which are called the K and K ' points. Because of the peculiar linear energy spectrum, graphene provides an environment for highly unconventional and fascinating two-dimensional (2D) electronic properties [3-5] such as the half-integer quantum Hall e?ect [6, 7], the absence of backward scattering [4, 8, 9], Klein tunneling [10], and the p - phase shift of Shubnikov-de Haas oscillations [11]. Owing to its high electronic mobility [12] and thermal conductivity [13], graphene is recognized as one of the key materials for realizing next-generation electronic devices.