Theory of neutral and charged exciton scattering with electrons in semiconductor quantum wells

Ramon, Guy; Mann, A.; Cohen, E.

doi:10.1103/physrevb.67.045323

Cited by 53 publications

(67 citation statements)

References 43 publications

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“…In fact, the scattering rates depend on the free electron density. 25 In our model, if the electron density is higher than the critical value, n s , the rates are diminished by a factor k s . This change in the scattering rates generates the discontinuity presented in Fig.…”

Section: Discussionmentioning

confidence: 86%

Kinetics of excitonic complexes on tunneling devices

et al. 2005

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In this work we have investigated the effects of trion formation on the tunneling current from both experimental and theoretical viewpoints. We have measured the current-voltage characteristics and the quantum-well photoluminescence emission of GaAs-Ga 1−x Al x As n-i-n double barrier diodes. We have observed a preresonance shoulder in the current-voltage curve under high laser intensities associated with the formation of trions in the quantum well, which increase the number of free states in the resonant and excitonic levels, thus enhancing the tunneling mechanism. These excitonic complexes were detected through the photoluminescence spectra under bias. We have observed that the preresonance shoulder occurs under the same conditions for which a trion peak in the luminescence spectrum is present. This trion-assisted mechanism is terminated when neutral and charged excitons are dissociated either by thermal excitation or by scattering with free carriers in the quantum well. A phenomenological rate equation model has allowed us to confirm our assumptions on the effect of trion formation on the charge transport.

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Section: Discussionmentioning

confidence: 86%

Kinetics of excitonic complexes on tunneling devices

et al. 2005

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“…Electrons, for instance, are known to strongly screen the exciton oscillator strength 8,9 and to modify their linewidth and binding energy through exchange interactions. 10 Thus, the shape of the exciton line, as well as that of the trion line, depends strongly on the strength of electron scattering with excitons and trions. Indeed, we have observed, as others before us, that a high-energy tail develops at both exciton and trion resonances upon increasing electron concentration.…”

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confidence: 99%

Dressed excitons within an incoherent electron gas: Observation of a Mollow triplet and an Autler-Townes doublet

2008

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We demonstrate that the interaction between excitons and a sea of incoherent electrons does not preclude excitons dressing by light. We investigate if exciton-electron scattering plays some inhibiting role in the coherent light-exciton coupling by measuring the dynamical absorption spectrum of a modulation-doped CdTe quantum well that shows clear evidence for significant electron scattering of the excitonic states. We show the occurrence of dressed and correlated excitons by detecting quantum coherent interferences through excitonic Autler-Townes doublet and ac Stark splitting that evolves into a Mollow triplet with gain. We also evidence the partial inhibition of the electron-exciton scattering by exciton-light coupling. DOI: 10.1103/PhysRevB.77.121301 PACS number͑s͒: 78.67.De, 71.35.Cc, 71.35.Ee, 78.47.Ϫp The absorption spectrum of semiconductor quantum wells is dominated by a strong exciton resonance. Excitons are bound, conduction electron valence-hole pairs and are quite often compared to a two level system as a hydrogen atom. The role of many body interactions and exciton correlations in the exciton dynamical absorption spectrum has attracted much interest for several decades. The response of the exciton absorption to an incoherent and thermalized electronhole population obtained through nonresonant pumping in the continuum corresponds mainly to a broadening of the exciton resonance that is dominated by collision broadening ͑excitation-induced dephasing͒ rather than by a bleaching due to the saturation of the oscillator strength caused by phase space filling.1 The effect increases with electron-hole concentration. In the regime of coherent pumping at the exciton resonance, the light-field dresses the electron-hole gas and dynamical Stark splitting has been clearly observed in GaAs quantum wells embedded 2 or not 3,4 in a microcavity. Actually, in this coherent regime, the excitation-induced dephasing is found to be reduced as a result of the significant decrease of the Coulomb collision rates.5 As a consequence, the light-induced exciton dressing renders this many-body excitonic system comparable to a noninteracting atom system. 6 This issue is very important if one tries to extend coherent manipulations as those performed in atomic systems 7 to semiconductors in view of possible applications. In modulation-doped semiconductor quantum wells, excess carriers coalesce with excitons to form charged excitons ͑trions͒. The absorption spectrum is then modified: a trion resonance appears below the exciton resonance.8 However, many-body interactions also tend to become more complex. Electrons, for instance, are known to strongly screen the exciton oscillator strength 8,9 and to modify their linewidth and binding energy through exchange interactions.10 Thus, the shape of the exciton line, as well as that of the trion line, depends strongly on the strength of electron scattering with excitons and trions. Indeed, we have observed, as others before us, that a high-energy tail develops at both exciton and trion res...

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“…34 which cannot be computed analytically. Differently from the direct interaction term, the exchange term contains the factor e − 2 L 0 coming from the overlap integral between wave functions of the electron forming the exciton and the free electron from the 2DEG and decays exponentially with increasing distance between QWs even at q = 0.…”

Section: Effective Interactions In a Hybrid Bose-fermi Systemmentioning

confidence: 99%

Elementary excitations in spinor polariton-electron systems

Kyriienko

Shelykh

2011

Phys. Rev. B

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We consider effective interactions in a two-dimensional (2D) hybrid polariton-electron system and calculate dispersion of elementary excitations by accounting for the spin degrees of freedom of the particles. Due to the crucial role played by the exchange term in polariton-electron interactions the dispersions of this system become spin dependent and show unusual behavior. The coupling of the excitations of the condensate with 2D plasmons can result in the appearance of roton minimum in the dispersion and destruction of the condensate for close enough situated quantum wells with electrons and excitons.

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Theory of neutral and charged exciton scattering with electrons in semiconductor quantum wells

Cited by 53 publications

References 43 publications

Kinetics of excitonic complexes on tunneling devices

Kinetics of excitonic complexes on tunneling devices

Dressed excitons within an incoherent electron gas: Observation of a Mollow triplet and an Autler-Townes doublet

Elementary excitations in spinor polariton-electron systems

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