Time-Domain Ab Initio Simulation of Electron and Hole Relaxation Dynamics in a Single-Wall Semiconducting Carbon Nanotube

Bradley F. Habenicht, Colleen F. Craig, and Oleg V. Prezhdo

Phys. Rev. Lett. 96, 187401 – Published 11 May 2006; Erratum Phys. Rev. Lett. 98, 189901 (2007)

Abstract

The electron and hole relaxation in the $(7, 0)$ zigzag carbon nanotube is simulated in time domain using a surface-hopping Kohn-Sham density functional theory. Following a photoexcitation between the second van Hove singularities, the electrons and holes decay to the Fermi level on characteristic subpicosecond time scales. Surprisingly, despite a lower density of states, the electrons relax faster than the holes. The relaxation is primarily mediated by the high-frequency longitudinal optical (LO) phonons. Hole dynamics are more complex than the electron dynamics: in addition to the LO phonons, holes couple to lower frequency breathing modes and decay over multiple time scales.