Transport and Optical Properties of Carbon Nanotubes

Keywords:
mobility, saturation, excitons, optical efficiency

Abstract:
Carbon nanotubes (CNTs) have remarkable optical and transport
properties, with important implications for technology. They have
extraordinarily high electron and hole mobilities at low fields,
although the mobility saturates at high fields. We calculate the
electron-phonon scattering and mobility using a multi-band
Boltzmann treatment. We developed scaling relationships for the
mobility of carriers in CNTs as a function of electric field,
carrier density, temperature and chirality [1, 2] to provide a
broad overview of the transport. The optical properties are also
unusual, being dominated by excitons, with binding energies and
oscillator strengths that are orders of magnitude larger than
those in conventional semiconductors. We find simple scaling
relationships for the exciton oscillator strength and binding
energy as a function of the tube chirality and the dielectric
constant of the embedding material [3]. We calculate the exciton
radiative lifetime, which in turn determines the efficiency of
opto-electronic CNT devices. We predict an unusual nonmonotonic
temperature dependence, due to optically inactive exciton bands
below the optically active exciton [4].
 
References
 
[1] V. Perebeinos, J. Tersoff, and Ph. Avouris, Phys. Rev. Lett.
94, 086802 (2005).
 
[2] V. Perebeinos, J. Tersoff, and Ph. Avouris, cond-mat/0510638.
 
[3] V. Perebeinos, J. Tersoff, and Ph. Avouris, Phys. Rev. Lett.
92, 257402 (2004).
 
[4] V. Perebeinos, J. Tersoff, and Ph. Avouris, Nano Letter (in
press).

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Nanotech 2006 Conference Program Abstract