Abstract
We investigate the time- and momentum-resolved relaxation dynamics of nonequilibrium charge carriers in semiconducting carbon nanotubes. Using density matrix theory, we derive Markovian equations for intra- and intersubband transitions driven by electron-phonon scattering. Focusing on a two-subband model, we study the relaxation times as a function of the excitation energy, the nanotube diameter, and the chiral angle. Our calculations reveal that the relaxation dynamics is very sensitive to the diameter of the tube, which is correlated with the diameter dependence of the electron-phonon coupling element. We observe the fastest relaxation dynamics for zig-zag nanotubes with a small diameter and at low excitation energies. For tubes with a large chiral angle (close to the armchair configuration), the relaxation time increases by approximately 35.
- Received 25 March 2011
DOI:https://doi.org/10.1103/PhysRevB.84.153407
©2011 American Physical Society