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arXiv · 1407.0593

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. Vuckovic·R. Gross·M. Kaniber·J. J. Finley
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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 $\pm$ 0.07 ns to 0.10 $\pm$ 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 ($τ_r$) 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 -2/3 power law dependence of the rise time 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.

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G. Reithmaier, F. Flassig, P. Hasch, S. Lichtmannecker, K. Müller, J. Vuckovic, R. Gross, M. Kaniber, J. J. Finley. 2014-08-15. A carrier relaxation bottleneck probed in single InGaAs quantum dots using integrated superconducting single photon detectors. https://doi.org/10.1063/1.4894239

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