Raman spectroscopic evidence for hot-phonon generation in electrically biased carbon nanotubes.
We provide spectroscopic evidence for hot-phonon generation in biased single-walled carbon nanotubes by measuring simultaneously the Stokes and anti-Stokes Raman lines of the G mode and of the radial-breathing mode as a function of current bias. Using Bose-Einstein statistics we can directly calculate the phonon temperature from the intensity ratio of the anti-Stokes to Stokes lines. Upon nanotube biasing we observe (i) an increase of the G mode phonon temperature in contrast to the radial-breathing mode phonons that remain thermalized at room temperature, and (ii) no softening of the G mode. Based on these observations, we exclude current-induced thermal heating of the nanotube.
Oron-Carl
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M
Institut für Nanotechnologie, Forschungszentrum Karlsruhe, 76344 Eggenstein-Leopoldshafen, Germany.
Krupke
R
R