Thermodynamic origin of the slow free exciton photoluminescence rise in GaAs

Beck, Michael Edmund; Hübner, Jens; Oestreich, M.; Bieker, S.; Henn, T.; Kießling, T.; Ossau, W.; Molenkamp, Laurens W.

doi:10.1103/physrevb.93.081204

Cited by 17 publications

(10 citation statements)

References 37 publications

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“…The bare mass of the free exciton is m x = m n +m p , and we assume that the difference between the bare and effective exciton mass-defined as the inverse curvature of an excitonic band close to its minimumis negligible . The analogue of the Saha's equation for semiconductors reads [39,40]…”

Section: Exciton Dissociation Equilibriummentioning

confidence: 99%

An excitonic model for the electron–hole plasma relaxation in proton-irradiated insulators

et al. 2021

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The relaxation of free electron–hole pairs generated after proton irradiation is modelled by means of a simplified set of hydrodynamic equations. The model describes the coupled evolution of the electron–hole pair and self-trapped exciton (STE) densities, along with the electronic and lattice temperatures. The equilibration of the electronic and lattice excitations is based on the two-temperature model, while two mechanisms for the relaxation of free electron–hole pairs are considered: STE formation and Auger recombination. Coulomb screening and band gap renormalisation are also taken into account. Our numerical results show an ultrafast ($${\ll }\,{\mathrm {1}}$$ ≪ 1 ps) free electron–hole pair relaxation time in amorphous $${{\mathrm {SiO}}_{\mathrm {2}}}$$ SiO 2 for initial carrier densities either below or above the exciton Mott transition. Coulomb screening alone is not found to yield the long relaxation time ($${\mathrm {\gg }}{\mathrm {10}}$$ ≫ 10 ps) experimentally observed in amorphous $${{\mathrm {SiO}}_{\mathrm {2}}}$$ SiO 2 and borosilicate crown glass BK7 irradiated with high-intensity laser pulses or BK7 irradiated by short proton pulses. Another mechanism, e.g. thermal detrapping of STEs, is required to correctly model the long free electron–hole pair relaxation time observed experimentally. Graphical Abstract

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Section: Exciton Dissociation Equilibriummentioning

confidence: 99%

An excitonic model for the electron–hole plasma relaxation in proton-irradiated insulators

et al. 2021

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“…The experimental studies undertaken in the past were based on two main methods. The first one is the study of the PL kinetics 15,[18][19][20][21][22][23][24][25][26] . This is an indirect method of study of excitons in the reservoir because the PL appears only after the last process, namely, the exciton scattering into the light cone.…”

Section: Introductionmentioning

confidence: 99%

“…The theoretical modeling of the dynamics of the excitonic reservoir is challenging as it may only rely on a scarce experimental data available. First attempts of this kind of modeling [33][34][35] are followed by an extensive and contradictory discussion of the major mechanisms of the formation of the exciton PL signal [21][22][23][24]26,30,32,36,37 . The widely used model assumes the formation of excitons in the reservoir by photoexcited electrons and holes.…”

Section: Introductionmentioning

confidence: 99%

“…The authors suggested that the PL signal at the exciton resonance frequency can be caused by the recombination of Coulomb-correlated electron-hole pairs rather than the excitonic recombination. This idea was experimentally tested in many works [21][22][23][24]26,30,32 however no general conclusion was drawn so far. The reasons for the persisting umbiguity regarding the origin of the exciton PL signal are: (1) there are too many processes are involved in the PL signal dynamics, (2) the rates of these processes are sensitive to particular experimental conditions, (3) the experimental information is not sufficient to draw certain conclusions about each of the processes involved.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics and control of nonradiative excitons - free carriers mixture in GaAs/AlGaAs quantum wells

Kurdyubov,

Trifonov,

Gribakin

et al. 2021

Preprint

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Dynamics of nonradiative excitons with large in-plane wave vectors forming a so-called reservoir is experimentally studied in a high-quality semiconductor structure containing a 14-nm shallow GaAs/Al0.03Ga0.97As quantum well by means of the non-degenerate pump-probe spectroscopy. The exciton dynamics is visualized via the dynamic broadening of the heavy-hole and light-hole exciton resonances caused by the exciton-exciton scattering. Under the non-resonant excitation free carriers are optically generated. In this regime the exciton dynamics is strongly affected by the excitoncarrier scattering. In particular, if the carriers of one sign are prevailing, they efficiently deplete the reservoir of the nonradiative excitons inducing their scattering into the light cone. A simple model of the exciton dynamics is developed, which considers the energy relaxation of photocreated electrons and holes, their coupling into excitons, and exciton scattering into the light cone. The model well reproduces the exciton dynamics observed experimentally both at the resonant and nonresonant excitation. Moreover, it correctly describes the profiles of the photoluminescence pulses studied experimentally. The efficient exciton-electron interaction is further experimentally verified by the control of the exciton density in the reservoir when an additional excitation creates electrons depleting the reservoir.

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“…However, at low temperatures the most important types of quasiparticles interacting with optically active excitons are the free carriers and other excitons, es-pecially non-radiative excitons with large in-plane wave vectors exceeding the wave vector of light. Although experimental studies of these interactions have been conducted for already three decades [25][26][27][28][29][30][31][32][33], important characteristics of these interactions, such as the physical mechanisms and the scattering cross-section, are still not uniquely determined. The problem lies in the densities of the quasiparticles, which cannot be determined directly from experiments with sufficient accuracy.…”

Section: Introductionmentioning

confidence: 99%

Exciton-exciton and exciton-charge carrier interaction and the exciton collisional broadening in GaAs/AlGaAs quantum wells

Gribakin,

Khramtsov,

Trifonov

et al. 2021

Preprint

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Wave functions of heavy-hole excitons in GaAs/Al0.3Ga0.7As square quantum wells (QWs) of various widths are calculated by the direct numerical solution of a three-dimensional Schrödinger equation using a finite-difference scheme. These wave functions are then used to determine the exciton-exciton, exciton-electron and exciton-hole fermion exchange constants in a wide range of QW widths (5 − 150 nm). Additionally, the spin-dependent matrix elements of elastic excitonexciton, exciton-electron and exciton-hole scattering are calculated. From these matrix elements, the collisional broadening of the exciton resonance is obtained within the Born approximation as a function of the areal density of excitons, electrons and holes respectively for QW widths of 5, 15, 30 and 50 nm. The obtained numerical results are compared with other theoretical works.

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Thermodynamic origin of the slow free exciton photoluminescence rise in GaAs

Cited by 17 publications

References 37 publications

An excitonic model for the electron–hole plasma relaxation in proton-irradiated insulators

An excitonic model for the electron–hole plasma relaxation in proton-irradiated insulators

Dynamics and control of nonradiative excitons - free carriers mixture in GaAs/AlGaAs quantum wells

Exciton-exciton and exciton-charge carrier interaction and the exciton collisional broadening in GaAs/AlGaAs quantum wells

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