Soutenance de thèse de Gaston Kane le 7 juin 2013 à 14H

IMPMC, Université P. et M. Curie, 4, Place Jussieu, 75005 Paris

Salle de Conférence, 4^e étage, Tour 22-23, Salle  401

High-field transport in graphene and carbon nanotubes

Abstract
Graphene and carbon nanotubes (carbon-based materials) are widely studied because of their peculiar physical properties, such as their ballistic behavior at room temperature or the high current density they can support. For their remarkable properties, graphene and carbon nanotubes are envisioned to be used in nanoelectronic devices. A good understanding of the electron transport properties of these materials is thus necessary to achieve such a goal. This thesis focuses on the theoretical study of electron transport in carbon nanotubes and graphene. We precisely study the impact of the Zener tunneling effect (interband transitions induced by an electric field through a forbidden band gap) on the transport properties of quasi-metallic nanotubes (Qm), characterized by a band gap of a few tens of milli-electron volts, and graphene. By using a model based on the master equation, we have shown that in the presence of tunneling, Qm nanotubes support an electrical current even when the Fermi energy lies in the forbidden band gap. We have also shown that the Zener tunneling is observable at low electric fields (<1V/μm) in the presence of defects (low quality sample), while the presence of a small number of defects (good quality sample) requires high electric fields (>1V/μm) for the observation of this effect. In graphene, the study of the electron transport in the nonlinear regime have required adding the electron-electron scattering, in addition to electron-defect and electron-phonon collisions to reach a thermal equilibrium. By using a simplified model of the electron-electron scattering, we have shown that our theoretical model can qualitatively describe the experimental findings.

Composition du jury
M. Christophe DELERUE Rapporteur
M. Ralph GEBAUER Rapporteur
M. Bernard PLAÇAIS Examinateur
Mme Jéléna SJAKSTE Examinatrice
M. Francesco MAURI Directeur
M. Michele LAZZERI Invité (Co-directeur)