Dynamics of unidirectional phonon-assisted transport of photoexcited carriers in step-graded Inx(Al0.17Ga0.83)1xAs/Al0.17Ga0.83As multiple quantum wells

S. Machida, M. Matsuo, K. Fujiwara, J. R. Folkenberg, and J. M. Hvam
Phys. Rev. B 67, 205322 – Published 27 May 2003
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Abstract

The dynamics of perpendicular transport of photoexcited carriers assisted by phonon scattering is investigated in a novel step-graded Inx(Al0.17Ga0.83)1xAs quantum-well heterostructure by measuring the temperature dependence of spectrally and temporally resolved photoluminescence (PL). When builtin potential gradients are present in the quantum-well heterostructure due to variations in the In mole fraction (x) in the well, carriers that are thermally released by the particular well move unidirectionally from shallower to deeper wells. That is, asymmetric unidirectional motion of photoexcited carriers is possible via phonon-assisted activation above the barrier band-edge state. We have directly measured this perpendicular motion of photoexcited carriers by monitoring the transient PL signals from the different wells, which are spectrally separated. A rate equation analysis rigorously explains the dynamical changes of the PL signal intensities from the quantum wells as a function of lattice temperature. Our study of PL dynamics proves the asymmetric perpendicular flow of photoexcited carriers and the capture by the deeper quantum wells, providing firm evidence for the dynamical carrier flow and capture processes in the novel heterostructure.

  • Received 8 October 2002

DOI:https://doi.org/10.1103/PhysRevB.67.205322

©2003 American Physical Society

Authors & Affiliations

S. Machida, M. Matsuo, and K. Fujiwara*

  • Kyushu Institute of Technology, Tobata, Kitakyushu 804-8550, Japan

J. R. Folkenberg

  • Crystal Fibre A/S, Blokken 84, DK-3460 Birkerød, Denmark

J. M. Hvam

  • Research Center COM, Technical University of Denmark, Building 349, DK-2800 Kgs. Lyngby, Denmark

  • *Author to whom correspondence should be addressed. Electronic address: fujiwara@ele.kyutech.ac.jp

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Vol. 67, Iss. 20 — 15 May 2003

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