A carrier relaxation bottleneck probed in single InGaAs quantum dots using integrated superconducting single photon detectors

G. Reithmaier, F. Flassig, P. Hasch, S. Lichtmannecker, K. Müller, J. Vučković, R. Gross, M. Kaniber, J. J. Finley

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Using integrated superconducting single photon detectors, we probe ultra-slow exciton capture and relaxation dynamics in single self-assembled InGaAs quantum dots embedded in a GaAs ridge waveguide. Time-resolved luminescence measurements performed with on- and off-chip detection reveal a continuous decrease in the carrier relaxation time from 1.22 ± 0.07 ns to 0.10 ± 0.07 ns upon increasing the number of non-resonantly injected carriers. By comparing off-chip time-resolved spectroscopy with spectrally integrated on-chip measurements, we identify the observed dynamics in the rise time (τr) as arising from a relaxation bottleneck at low excitation levels. From the comparison with the temporal dynamics of the single exciton transition with the on-chip emission signal, we conclude that the relaxation bottleneck is circumvented by the presence of charge carriers occupying states in the bulk material and the two-dimensional wetting layer continuum. A characteristic τr ∝ P-2/3 power law dependence is observed suggesting Auger-type scattering between carriers trapped in the quantum dot and the two-dimensional wetting layer continuum which circumvents the phonon relaxation bottleneck.

Original languageEnglish
Article number081107
JournalApplied Physics Letters
Volume105
Issue number8
DOIs
StatePublished - 25 Aug 2014

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