Radiative behavior of negatively charged excitons in CdTe-based quantum wells: A spectral and temporal analysis

Ciulin, V.; Kossacki, P.; Haacke, Stefan; Ganière, Jean‐Daniel; Deveaud, B.; Esser, A.; Kutrowski, M.; Wójtowicz, T.

doi:10.1103/physrevb.62.r16310

Cited by 76 publications

(89 citation statements)

References 26 publications

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“…Apart from a factor of 1.5 attributed to the Bragg mirrors that enhances the coupling of the excitons and charged excitons to the field and hence diminishes the radiative decay time, the agreement with the expected theoretical behavior is very good [10,11,27].…”

supporting

confidence: 55%

“…Additionally, the abundance of free electrons in the solar atmosphere is indirectly measured in terms of H À concentration. In semiconductor quantum wells (QWs), trions show a number of properties very similar to excitons [4], such as strong coupling in microcavities [5], absorption bleaching [6,7], transport [8] and diffusion [9] properties, and radiative recombination efficiency [10,11], and thus have attracted considerable interest. Moreover, trions promise to play a key role in future applications, notably in quantum-information science [12] and in the future development of all-spin-based scalable quantum computers [13,14].…”

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confidence: 99%

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Dynamics of Trion Formation inInxGa1−xAsQuantum Wells

et al. 2009

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We show a double path mechanism for the formation of charged excitons (trions); they are formed through bi-and trimolecular processes. This directly implies that both negatively and positively charged excitons coexist in a quantum well, even in the absence of excess carriers. The model is substantiated by time-resolved photoluminescence experiments performed on a very high quality In x Ga 1Àx As quantum well sample, in which the photoluminescence contributions at the energy of the trion and exciton and at the band edge can be clearly separated and traced over a broad range of times and densities. The unresolved discrepancy between the theoretical and experimental radiative decay time of the exciton in a doped semiconductor quantum well is explained by the same model. Positively and negatively charged excitons (X þ and X À trions) [1,2] are usually compared to their atomic counterpart ions of helium He þ and hydrogen H À , respectively. In astronomy, the dynamics of the formation of these atomic ions is of great importance [3]; indeed, H À is the primary source of the continuum opacity in most stellar photospheres and contributes to the production of hydrogen and other elements in various parts of the Universe. Additionally, the abundance of free electrons in the solar atmosphere is indirectly measured in terms of H À concentration. In semiconductor quantum wells (QWs), trions show a number of properties very similar to excitons [4], such as strong coupling in microcavities [5], absorption bleaching [6,7], transport [8] and diffusion [9] properties, and radiative recombination efficiency [10,11], and thus have attracted considerable interest. Moreover, trions promise to play a key role in future applications, notably in quantum-information science [12] and in the future development of all-spin-based scalable quantum computers [13,14]. They are correlated with excitons and the free carrier plasma and offer the possibility to test a model of formation of three-particle complexes.The formation process of neutral excitons (X) in QWs has been extensively investigated over the past two decades [15,16] and recently shown to be strongly density-and temperature-dependent [17]. This is a bimolecular process, in which an electron (e) and a hole (h) are bound by Coulomb interaction with the emission of the appropriate phonon. Conversely, the formation process of trions has been much less studied. It is largely believed that trions can be formed only if a population of excess carriers is trapped in the well, producing exclusively trions with the same charge. Consequently, existing models discriminate the formation channel yielding trions of opposite charge. Current models for trion formation [18,19] surmise that trions are exclusively formed through a bimolecular process, i.e., the coalescence of an exciton and a charged free carrier. While this is conceivable at low densities, nothing attests that genuine formation of the trion from an unbound electron-hole plasma (trimolecular formation) is negligible at higher densities.In...

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confidence: 55%

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confidence: 99%

Dynamics of Trion Formation inInxGa1−xAsQuantum Wells

et al. 2009

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“…The sample studied here has been fully characterized in previous studies [10][11][12][13]. It is a one-sided graded modulation-doped CdTe/CdMgTe heterostructure containing a single quantum well of 8 nm.…”

Section: Methodsmentioning

confidence: 99%

“…3b and c). At these temperatures, the homogeneous broadening of the electron distribution is essentially due to electron-acoustic phonon scattering, which is the dominant electron scattering process in this temperature range [11]. Therefore, the exciton-electron interaction does not modify the electron distribution enough to induce an increase in the trion absorption at low energies.…”

Section: Resonant Excitation Of Neutral Excitonsmentioning

confidence: 98%

Many-Body Interaction Evidenced through Exciton-Trion-Electron Correlated Dynamics

et al. 2004

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Interactions among excitons, trions, and electrons are studied in CdTe modulation-doped quantum wells. These many-body interactions are investigated through the nonlinear dynamical properties in the excitonic complexes using time and spectrally resolved pump and probe techniques. This study is performed as a function of temperature and densities of excitons, trions, and electrons. The results reveal that the nonlinearities induced by trions differ from those induced by excitons and moreover they are mutually correlated. The correlated behavior of excitons and trions manifests itself by crossed trion-exciton effects. We propose that the main source of these correlations is due to the presence of electrons in the quantum well and that its physical origin is the Pauli exclusion-principle. We find that, at 5 K, trions are formed from excitons within 10 ps; at 20 K a thermal equilibrium is reached within 5 ps.

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“…In the latter two cases the exciton, after its formation, is attached to an existing free electron (or hole). The dynamics of the three processes are different 7 . The other method involves the injection of electrons and holes by doping regions close to the structure.…”

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The role of excitons and trions on electron spin polarization in quantum wells

Aceituno¹,

Hernández‐Cabrera²

2011

Journal of Applied Physics

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We have studied the time evolution of the electron spin polarization under continuous photoexcitation in remotely n-doped semiconductor quantum wells. The doped region allows us to get the necessary excess of free electrons to form trions. We have considered electron resonant photoexcitation at free, exciton and trion electron energy levels. Also, we have studied the relative effect of photoexcitation energy density and doping concentration. In order to obtain the two-dimensional density evolution of the different species, we have performed dynamic calculations through the matrix density formalism. Our results indicate that photoexcitation of free electron level leads to a higher spin polarization. Also, we have found that increasing the photoexcitation energy or diminishing the doping enhances spin polarization.

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Radiative behavior of negatively charged excitons in CdTe-based quantum wells: A spectral and temporal analysis

Cited by 76 publications

References 26 publications

Dynamics of Trion Formation inInxGa1−xAsQuantum Wells

Dynamics of Trion Formation inInxGa1−xAsQuantum Wells

Many-Body Interaction Evidenced through Exciton-Trion-Electron Correlated Dynamics

The role of excitons and trions on electron spin polarization in quantum wells

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