High-field transport in graphene and carbon nanotubes

Drift response to a high electric field in graphene and carbon nanotubes (CNTs) is delineated using nonequilibrium Arora distribution function (NEADF), a paradigm that is distinctly different from that using the nonequilirium Green function and other theoretical paradigms. In this formalism, the re-organization of randomly oriented velocity vectors is shown to streamline and become unidirectional leading to the saturation of drift velocity and drift current. Experiments on CNTs show the resistance rises in response to the applied voltage that may or may not be independent of temperature depending on degeneracy of the sample. We show that the drift response to the high electric field is consistent with anisotropic NEADF. The formalism so developed explains very well the experimental results, not only in graphene nanostructures, but also in other semiconducting materials. Quantum processes and high-field mechanisms are discussed as linear energy versus momentum relationship in graphene is considered. The results will prove of value to those involved in characterization and performance evaluation of nanoscale devices.