Nonequilibrium dynamics of free quantum-well excitons in time-resolved photoluminescence

Scattering rates of quantum-well excitons by acoustic phonons are calculated using realistic deformation potentials for electrons and holes in structures based on GaAs. These fates are used in order to reproduce the exciton dynamics in a time-resolved photoluminescence experiment. Rise time and decay time of the luminescence signal are studied as a function of temperature and quantum-well size. It is found that the exciton distribution function reaches a stationary shape during the radiative recombination and shows strong deviations from the thermal distribution. As a consequence, the decay time is slower. A discussion of the dependence of these effects on the well width is given.

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Vincenzo Savona, Paolo Schwendimann
1996
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https://infoscience.epfl.ch/record/141192?ln=fr

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En physique, quantum (mot latin signifiant « combien » et dont le pluriel s'écrit « quanta ») représente la plus petite mesure indivisible, que ce soit celle de l'énergie, de la quantité de mouvement

Phonon

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Effect of the scattering by phonons on the temperature dependence of the free QW exciton radiative lifetimes.

Vincenzo Savona, Paolo Schwendimann

We calculate scattering rates of QW excitons by acoustic phonons using realistic deformation potentials for electrons and holes in structures based on GaAs. We use these rates in order to reproduce the exciton dynamics in a time-resolved photoluminescence experiment. Rise time and decay time of the luminescence signal are studied as a function of temperature and QW size. The exciton distribution function reaches a stationary shape after the luminescence passes through its maximum. This shape shows strong deviations from the thermal-equilibrium distribution, at least for temperatures below 50 K. As a consequence, exciton radiative recombination is slower than the usually expected thermal average of the radiative rate. We discuss the dependence of this effect on the well width.

1995

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Monte Carlo model for the photoluminescence kinetics of a quantum dot embedded in a nanocavity

Vincenzo Savona, Guillaume Jean Tarel

We address the problem of the photoluminescence of a quantum (QD) dot in a nanocavity, with focus on the case of nonzero detuning. In this regime, experiments have shown that strong emission from the cavity-like peak is still present for dot-cavity detuning exceeding 10 meV, which seems puzzling. We will discuss the general theory of cavity feeding, due to the relaxation and recombination kinetics of a multiply excited QD. We first compute the multi-exciton manifolds using a configuration-interaction scheme, starting from a truncated single-particle basis. We then run Monte-Carlo paths of excitation-emission kinetics on these states. This allows to extract photoluminescence spectra and two-photon correlation curves. The agreement with experimental data[1, 2] is very good. Our result shows unambiguously that the cavity feeding mechanism at large detunings can be attributed to excited-state multiexciton radiative decay (mostly biexcitons), also involving states in the wetting layer continuum.

Iop Publishing Ltd, Dirac House, Temple Back, Bristol Bs1 6Be, England2009

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Temperature-Dependence of Exciton Radiative Recombination in (Al,Ga)N/GaN Quantum Wells Grown on a-Plane GaN Substrates

Pierre Michel Corfdir, Benoît Marie Joseph Deveaud, Jean-Daniel Ganière, Etienne Giraud, Nicolas Grandjean, Mehran Shahmohammadi

This article presents the dynamics of excitons in a-plane (Al,Ga)N/GaN single quantum wells of various thicknesses grown on bulk GaN substrates. For all quantum well samples, recombination is observed to be predominantly radiative in the low-temperature range. At higher temperatures, the escape of charge carriers from the quantum well to the (Al,Ga)N barriers is accompanied by a reduction in internal quantum efficiency. Based on the temperature-dependence of time-resolved photoluminescence experiments, we also show how the local disorder affects the exciton radiative lifetime at low temperature and the exciton non-radiative lifetime at high temperature. (C) 2013 The Japan Society of Applied Physics

Japan Society of Applied Physics2013

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