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Gulia, M.; Rossi, Fausto; Molinari, Elisa; Selbmann, P.E.; Lugli, Paolo

doi:10.1103/physrevb.55.r16049

Cited by 38 publications

(22 citation statements)

References 8 publications

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“…Monitoring the time-dependent photoluminescence (PL) collected at the 1s-exciton resonance therefore yields information about the dynamics of these exciton populations. The build-up of the PL after nonresonant excitation has been interpreted as build-up of an incoherent exciton population 5,6,7,8,9,10 , and the subsequent fall off was taken as evidence for this population decay 2,11 . However, a recently developed microscopic luminescence theory for a Coulomb correlated plasma of electron-hole pairs predicts that luminescence peaks at the 1s-exciton resonance even without the presence of incoherent exciton populations 12 .…”

Section: Introductionmentioning

confidence: 99%

Many-body dynamics and exciton formation studied by time-resolved photoluminescence

et al. 2005

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The dynamics of exciton and electron-hole plasma populations is studied via time-resolved photoluminescence after nonresonant excitation. By comparing the peak emission at the exciton resonance with the emission of the continuum, it is possible to experimentally identify regimes where the emission originates predominantly from exciton and/or plasma populations. The results are supported by a microscopic theory which allows one to extract the fraction of bright excitons as a function of time.

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Section: Introductionmentioning

confidence: 99%

Many-body dynamics and exciton formation studied by time-resolved photoluminescence

et al. 2005

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“…Time-resolved photoluminescence spectroscopy is widely used to investigate the kinetics of free exciton formation, relaxation, and recombination in semiconductors and their nanostructures [1]. In most experiments performed at low lattice temperatures a significantly delayed onset of the free exciton luminescence with respect to the excitation laser pulse is observed [2][3][4][5][6][7][8][9][10][11][12][13]. This slow photoluminescence (PL) rise has attracted intense research interest for nearly three decades.…”

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confidence: 99%

Thermodynamic origin of the slow free exciton photoluminescence rise in GaAs

et al. 2016

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We use time-resolved photoluminescence (TRPL) spectroscopy to unequivocally clarify the microscopic origin of the nanosecond free exciton photoluminescence rise in GaAs at low temperatures. In crucial distinction from previous work, we examine the TRPL of the GaAs free exciton second LO-phonon replica. This enables us to simultaneously monitor the unambiguous time evolution of the total exciton population and the cooling dynamics of the initially hot free exciton ensemble. We demonstrate by a model based on the Saha equation and the experimentally determined cooling behavior that the long-debated slow photoluminescence rise is caused by time-dependent shifts in the thermodynamic quasiequilibrium between free excitons and the uncorrelated electron-hole plasma.

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“…1 For a long time, photoluminescence (PL) at the spectral position of the 1s exciton resonance has been considered as evidence for the existence of excitons. The rise of the 1s PL after nonresonant excitation of a semiconductor was interpreted as buildup of an excitonic population [1,2,3,4,5,6], and the PL decay was used to describe exciton recombination [7,8]. However, recently a microscopic theory predicted that PL at the 1s resonance can also originate from correlated plasma emission [9].…”

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Excitonic Photoluminescence in Semiconductor Quantum Wells: Plasma versus Excitons

et al. 2004

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Time-resolved photoluminescence spectra after nonresonant excitation show a distinct 1s resonance, independent of the existence of bound excitons. A microscopic analysis identifies excitonic and electron-hole plasma contributions. For low temperatures and low densities the excitonic emission is extremely sensitive to even minute optically active exciton populations making it possible to extract a phase diagram for incoherent excitonic populations. 1 For a long time, photoluminescence (PL) at the spectral position of the 1s exciton resonance has been considered as evidence for the existence of excitons. The rise of the 1s PL after nonresonant excitation of a semiconductor was interpreted as buildup of an excitonic population [1,2,3,4,5,6], and the PL decay was used to describe exciton recombination [7,8]. However, recently a microscopic theory predicted that PL at the 1s resonance can also originate from correlated plasma emission [9]. Accordingly, PL at the spectral position of the 1s resonance would not prove the existence of excitons, and previous interpretations may be in question. Indeed, in nonresonantly excited time resolved PL measurements the 1s resonance is developed on a sub-ps timescale at 100 K [10], much faster than any expected exciton formation time.Information about exciton formation can be gained by performing THz experiments [11].However, currently the THz results are inconclusive: Kaindl et al. [12] observed the buildup of the induced absorption corresponding to the excitonic 1s to 2p transition showing excitonic populations with formation times on a rather slow timescale of 100's of ps to ns. They claim to observe a nearly completely excitonic system 1 ns after excitation, while Chari et al. [13] only plasma contributions. Also, THz absorption is sensitive to both dark and bright excitons, and cannot answer if and how excitonic populations influence the PL.Here we address the following questions. Is the 1s PL ever dominated by plasma emission?If so, is it always dominated by plasma emission, i.e. what can we learn about excitonic populations from the 1s PL and nonlinear absorption?After ps continuum excitation, time resolved PL and corresponding probe absorption measurements are performed under identical conditions on a ns timescale. The sample (DBR42) consists of 20 MBE-grown 8 nm In 0.06 Ga 0.94 As quantum wells with 130 nm GaAs barriers; both sides are anti-reflection coated. This indium concentration places the 1s exciton resonance at 1.471 eV at 4 K, avoiding absorption in the bulk GaAs substrate that leads to impurity emission at 1.492 eV from unintentional carbon in the substrate. The results, checked on several other samples including a sample grown in a different MBE system, are insensitive to exciton linewidths or to interfacial or alloy disorder. Single-quantum-well data were noisier but exhibited a similar behavior, excluding significant radiative coupling effects.We excite nonresonantly 13.2 meV above the 1s resonance, into the heavy-hole continuum but below the light-h...

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Phonon-assisted exciton formation and relaxation in GaAs/AlxGa1
M. Gulia
¹
,
Fausto Rossi
²
,
Elisa Molinari
³

et al.

Cited by 38 publications

References 8 publications

Many-body dynamics and exciton formation studied by time-resolved photoluminescence

Many-body dynamics and exciton formation studied by time-resolved photoluminescence

Thermodynamic origin of the slow free exciton photoluminescence rise in GaAs

Excitonic Photoluminescence in Semiconductor Quantum Wells: Plasma versus Excitons

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Phonon-assisted exciton formation and relaxation in GaAs/AlxGa1M. Gulia1, Fausto Rossi2, Elisa Molinari3 et al.

Cited by 38 publications

References 8 publications

Many-body dynamics and exciton formation studied by time-resolved photoluminescence

Many-body dynamics and exciton formation studied by time-resolved photoluminescence

Thermodynamic origin of the slow free exciton photoluminescence rise in GaAs

Excitonic Photoluminescence in Semiconductor Quantum Wells: Plasma versus Excitons

Contact Info

Product

Resources

About

Phonon-assisted exciton formation and relaxation in GaAs/AlxGa1
M. Gulia
¹
,
Fausto Rossi
²
,
Elisa Molinari
³

et al.