We investigate theoretically the rates of non-radiative decay of excited semiconducting nanotubes by a variety of decay mechanisms and compare with experimental findings. We find that the multi-phonon decay (MPD) of free excitons is too slow to be responsible for the experimentally observed lifetimes. However, MPD lifetimes of localized excitons could be 2-3 orders of magnitude shorter. We also propose a new decay mechanism that relies on a finite doping of nanotubes and involves exciton decay into an optical phonon and an intraband electron-hole pair. The resulting lifetime is in the range of 5 to 100 ps, even for a moderate doping level.
@article{arxiv.0804.0767,
title = {Phonon and Electronic Non-radiative Decay of Excitons in Carbon Nanotubes},
author = {Vasili Perebeinos and Phaedon Avouris},
journal= {arXiv preprint arXiv:0804.0767},
year = {2009}
}