Coulomb-induced emission dynamics and self-consistent calculations of type-II Sb-containing quantum dot systems

K. Gradkowski, T. J. Ochalski, N. Pavarelli, H. Y. Liu, J. Tatebayashi, D. P. Williams, D. J. Mowbray, G. Huyet, and D. L. Huffaker

Phys. Rev. B 85, 035432 – Published 20 January 2012

Abstract

This paper investigates the effects of Coulomb interactions on the emission dynamics of Sb-containing quantum dot (QD) systems under high excitation densities. Two different type-II confinements are studied: confined electrons with unconfined holes using InAs/GaAs QDs capped with a GaAsSb quantum well (type-IIa), and confined holes with unconfined electrons using GaSb/GaAs QDs capped with an InGaAs quantum well (type-IIb). Time-resolved photoluminescence experiments are compared with self-consistent numerical calculations using an 8-band k·p model. In both structures, we observe a significant blueshift of emission and wavelength-dependent radiative lifetimes, but with marked quantitative differences between the two systems: in the type-IIa, the blueshift is 12 meV with a change in lifetime from 1.4 ns to 2.0 ns, and in the type-IIb, the blueshift is 63 meV with lifetime change from 100 ps to 23 ns. We present a comprehensive explanation of all the important features of the experimental data in terms of Coulomb-induced changes to the carrier wave functions and confining potentials, with the separate confinement of the electrons and holes being a crucial factor.

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Received 8 December 2011

DOI:https://doi.org/10.1103/PhysRevB.85.035432

Authors & Affiliations

K. Gradkowski^1,2,*, T. J. Ochalski^1,2,†, N. Pavarelli^1,2, H. Y. Liu³, J. Tatebayashi⁴, D. P. Williams^1,2, D. J. Mowbray⁵, G. Huyet^1,2, and D. L. Huffaker⁶

¹Tyndall National Institute, University College Cork, Cork, Ireland
²Centre for Advanced Photonics and Process Analysis, Cork Institute of Technology, Cork, Ireland
³Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom
⁴Institute for Nano Quantum Information Electronics, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
⁵Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
⁶Department of Electrical Engineering, California NanoSystems Institute, University of California, Los Angeles, California 90095, USA

^*Current address: Institute of Chemistry, Hebrew University of Jerusalem, Givat Ram, 91904 Jerusalem, Israel.
^†Corresponding author: tomasz.ochalski@tyndall.ie

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Vol. 85, Iss. 3 — 15 January 2012

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