Ultrafast carrier capture dynamics in InGaAs/GaAs quantum wires.

Authors :: Cooke, D. G.
Hegmann, F. A.
Mazur, Yu. I.
Wang, Zh. M.
Black, W.
Wen, H.
Salamo, G. J.
Mishima, T. D.
Lian, G. D.
Johnson, M. B.
Source :: Journal of Applied Physics. Jan2008, Vol. 103 Issue 2, p023710. 8p. 2 Diagrams, 6 Graphs.
Publication Year :: 2008
Abstract: We use time-resolved terahertz-pulse spectroscopy to study the ultrafast carrier dynamics in InGaAs/GaAs (311)A quantum wires. Anisotropy in the photoconductive dynamics is observed when aligning the terahertz probe polarization parallel versus perpendicular to the wire direction. The origin of this anisotropy is the carrier capture into localized quantum-wire states from delocalized wetting layer or barrier regions over time scales from 6 to 30 ps. The capture efficiency is found to be strongly temperature dependent, with thermal emission dominating above 125 K, while state-filling effects within the wires influence the capture rate below 125 K. Transient spectroscopy reveals a Drude-like carrier conductivity. [ABSTRACT FROM AUTHOR]