Radiative lifetimes of excitons in quantum wells: Localization and phase-coherence effects

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.

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“…17) With N loc and N fr the density of localized and free QW excitons, respectively, one gets, in the simplest possible picture:…”

Section: Resultsmentioning

confidence: 99%

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

Corfdir

Teisseyre

Suski

et al. 2013

Jpn. J. Appl. Phys.

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“…The first is the self-energy of a single QD coupled to the electromagnetic field, resulting in a finite radiative lifetime and an energy shift of the QD levels. This effect is well established and several theoretical estimates of the radiative lifetime of QDs have been proposed in the past years 15,16,17 . The second is the radiative coupling between different QDs.…”

Section: Introductionmentioning

confidence: 99%

“…(13). We compute these poles numerically within the exciton-pole approximation 4,5,6,7 , which consists in replacing the ω-dependence ofĜ αβ tensor by an average electron hole energyhω 0 . This approximation is generally valid when the dielectric medium does not present sharp resonances, as is the case in the present model where the QDs are embedded in a constant dielectric background.…”

Section: Theorymentioning

confidence: 99%

“…In this case the importance of the coupling, expressed by the magnitude of the polariton self-energy correction to the bare exciton energy, is considerably smaller. In quantum wells 2,4,5,6,7 , the polariton resonance implies a finite exciton radiative lifetime which is of the order of 10 ps in typical GaAs quantum wells, and a negligible shift of the exciton energy. A similar effect is predicted in quantum wires 8,9,10 .…”

Section: Introductionmentioning

confidence: 99%

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Long-range radiative interaction between semiconductor quantum dots

Parascandolo

Savona

2005

Phys. Rev. B

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We develop a Maxwell-Schrödinger formalism in order to describe the radiative interaction mechanism between semiconductor quantum dots. We solve the Maxwell equations for the electromagnetic field coupled to the polarization field of a quantum dot ensemble through a linear non-local susceptibility and compute the polariton resonances of the system. The radiative coupling, mediated by both radiative and surface photon modes, causes the emergence of collective modes whose lifetimes are longer or shorter compared to the ones of non-interacting dots. The magnitude of the coupling and the collective mode energies depend on the detuning and on the mutual quantum dot distance. The spatial range of this coupling mechanism is of the order of the wavelength. This coupling should therefore be accounted for when considering quantum dots as building blocks of integrated systems for quantum information processing.

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“…Thus the transition dipole strength and resulting radiative decay rate is a linear function of the coherence volume. [18][19][20][21][22] Feldmann et al demonstrated this linear relationship experimentally through the dependence of exciton lifetime on the temperaturedependent homogeneous spectral linewidth. 18 Later, a similar relationship was demonstrated between exciton radiative lifetime and QD size for CuCl microcrystals.…”

mentioning

confidence: 99%

Inhibited recombination of charged magnetoexcitons

et al. 1998

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Time-resolved photoluminescence measurements show that the decay time for charged excitons in a GaAs twodimensional electron gas increases by an order of magnitude at high magnetic fields. Unlike neutral excitons, the charged exciton center-of-mass is spatially confined in a "magnetically-adjustable quantum dot" by the cyclotron orbit and the quantum well. The inhibited recombination is explained by a reduced phase coherence volume of the magnetically-confined charged excitons.PACS numbers: 71.35. Ji, 8.47.+p, 73.20.D Charged excitons or "trions" were first identified in optical absorption experiments on electron-doped CdTe quantum well (QW) structures through their polarization properties in a magnetic field. 1 The negatively charged exciton (X − ) transition in a narrow QW was manifest in the spectra as a peak lying several meV below the uncharged exciton (X 0 ) peak. Although both X 0 and X − transitions may had been observed previously in PL spectra of GaAs QWs, the high electron density precluded their identification. 2 In hindsight, it is not surprising that the recently identified X − is often the most common exciton found in a system with excess electrons, similar to the X 0 in a system without excess electrons. An X 0 in the presence of excess electrons becomes polarized by a nearby electron and binds the electron by a dipolar attraction. The properties of X − transitions in GaAs QWs have been explored in several recent experimental 3-7 and theoretical [8][9][10][11][12] studies.An interesting facet of the charged exciton that has yet to be explored is the confinement produced by the cyclotron motion in a magnetic field. The X − complex (two electrons plus one hole) is singly-charged and a magnetic field confines the X − center-of-mass motion to a cyclotron orbit, unlike the neutral exciton (X 0 ) which is free to move in a magnetic field. This will be referred to as the magnetically-confined charged exciton (MCX). A magnetic field applied perpendicular to a twodimensional (2D) QW effectively confines the exciton to a quantum dot (QD) whose size is adjustable with magnetic field. The 3D MCX volume, defined roughly by the QW width and the area of the cyclotron orbit in the plane of QW, is inversely proportional to the perpendicular magnetic field, V M CX ∝ 1/B ⊥ . At high magnetic fields this volume is typically smaller than QDs currently available via patterned nanostructures.The purpose of the present study is to examine the radiative recombination of excitons confined in these MCX QDs. Exciton recombination times were determined by measuring the photoluminescence (PL) decay times in low-density GaAs/AlGaAs electron gases in magnetic fields to 18 T, at temperatures 0.5-7 K. At low temperatures, the X − decay time was found to increase by an order of magnitude for increasing perpendicular magnetic field. In contrast, the recombination is rapid for both the X − in fields applied in the plane of the QW and for the uncharged X 0 . In the latter two cases the exciton is not confined to a QD. The linear d...

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Radiative lifetimes of excitons in quantum wells: Localization and phase-coherence effects

Cited by 324 publications

References 34 publications

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

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

Long-range radiative interaction between semiconductor quantum dots

Inhibited recombination of charged magnetoexcitons

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