Signal propagation in carbon nanotubes of arbitrary chirality

Giovanni Miano, Carlo Forestiere, Antonio Maffucci, Sergey A. Maksimenko, Gregory Ya Slepyan

Research output: Contribution to journalArticlepeer-review

Abstract

In carbon nanotubes (CNTs) with large radii, either metallic or semiconducting, several subbands contribute to the electrical conduction, while in metallic nonarmchair nanotubes with small radii the wall curvature induces a large energy gap. In this paper, we propose a model for the signal propagation along single wall CNTs (SWCNTs) of arbitrary chirality, at microwave through terahertz frequencies, which takes into account both these characteristics in a self-consistent way. We first study an SWCNT, disregarding the wall curvature, in the frame of a semiclassical treatment based on the Boltzmann equation in the momentum-independent relaxation time approximation. It allows expressing the longitudinal dynamic conductivity in terms of the number of effective conducting channels. Next, we study the behavior of this number as the nanotube radius varies and its relation with the kinetic inductance and quantum capacitance. Furthermore, we show that the effects of the spatial dispersion are negligible in the collision dominated regimes, whereas they may be important in the collisionless regimes, giving rise to sound waves propagating with the Fermi velocity. Then, we study the effects on the electron transport of the terahertz quantum transition induced by the wall curvature by using a quantum kinetic approach. The nanotube curvature modifies the kinetic inductance and gives arise to an additional RLC branch in the equivalent circuit, related to the terahertz quantum transition. The proposed model can be used effectively for analyzing the signal propagation in complex structures composed of SWCNTs with different chirality, such as bundles of SWCNTs and multiwall CNTs, providing that the tunneling between adjacent shells may be disregarded.

Original languageEnglish
Article number5286295
Pages (from-to)135-149
Number of pages15
JournalIEEE Transactions on Nanotechnology
Volume10
Issue number1
DOIs
StatePublished - Jan 2011
Externally publishedYes

Keywords

  • Boltzmann transport equation
  • carbon nanotube (CNT)
  • conducting channels
  • curvature effects
  • interband transitions
  • transmission lines

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