Excitonic structure and pumping power dependent emission blue-shift of type-II quantum dots

Klenovský, Petr; Steindl, Petr; Geffroy, Dominique Alain

doi:10.1038/srep45568

Cited by 39 publications

(48 citation statements)

References 57 publications

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“…We have recently proposed one in Ref. [104], based on a semiself-consistent configuration interaction method (SSCCI) with an additional charge background due to impurities. In this model, the blueshift is then a result of "squeez-ing" of the wavefunction outside of the dot towards that inside.…”

Section: Gap Gaasmentioning

confidence: 99%

Optical response of (InGa)(AsSb)/GaAs quantum dots embedded in a GaP matrix

et al. 2019

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The optical response of (InGa)(AsSb)/GaAs quantum dots (QDs) grown on GaP (001) substrates is studied by means of excitation and temperature-dependent photoluminescence (PL), and it is related to their complex electronic structure. Such QDs exhibit concurrently direct and indirect transitions, which allows the swapping of Γ and L quantum confined states in energy, depending on details of their stoichiometry. Based on realistic data on QD structure and composition, derived from high-resolution transmission electron microscopy (HRTEM) measurements, simulations by means of k · p theory are performed. The theoretical prediction of both momentum direct and indirect type-I optical transitions are confirmed by the experiments presented here. Additional investigations by a combination of Raman and photoreflectance spectroscopy show modifications of the hydrostatic strain in the QD layer, depending on the sequential addition of QDs and capping layer. A variation of the excitation density across four orders of magnitude reveals a 50 meV energy blueshift of the QD emission. Our findings suggest that the assignment of the type of transition, based solely by the observation of a blueshift with increased pumping, is insufficient. We propose therefore a more consistent approach based on the analysis of the character of the blueshift evolution with optical pumping, which employs a numerical model based on a semi-self-consistent configuration interaction method.

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Section: Gap Gaasmentioning

confidence: 99%

Optical response of (InGa)(AsSb)/GaAs quantum dots embedded in a GaP matrix

et al. 2019

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“…On the one hand this approach allows a realistic treatment of the QD shape and composition 48,49 , including strain and piezoelectricity up to second order [50][51][52] . On the other hand it allows an intrinsic treatment of correlation effects, which are included in CI 31,49 via the excited SP states used to construct the Slater determinants. This is important, because we expect correlation effects between the confined carriers to play a dominant role in the weak confinement regime.…”

Section: Configuration Interaction Calculationsmentioning

confidence: 99%

“…We apply magnetic fields along the QD growth direction [001] (Faraday configuration) and along the [110] direction (Voigt configuration) and extract the diamagnetic coefficients and g-factors of several excited states in the GaAs QDs. To gain more insight into the physical properties of our QDs under an external magnetic field, we complement our experimental study with calculations using the method of Configuration interaction (CI) [28][29][30][31] . The theoretical results are in good agreement with the experimental data and confirm that correlation effects among the confined carriers have significant influence on the mag-netic properties.…”

Section: Introductionmentioning

confidence: 99%

Single-particle-picture breakdown in laterally weakly confining GaAs quantum dots

et al. 2019

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We present a detailed investigation of different excitonic states weakly confined in single GaAs/AlGaAs quantum dots obtained by the Al droplet-etching method. For our analysis we make use of temperature-, polarization-and magnetic field-dependent µ-photoluminescence measurements, which allow us to identify different excited states of the quantum dot system. Besides that, we present a comprehensive analysis of g-factors and diamagnetic coefficients of charged and neutral excitonic states in Voigt and Faraday configuration. Supported by theoretical calculations by the Configuration interaction method, we show that the widely used single-particle Zeeman Hamiltonian cannot be used to extract reliable values of the g-factors of the constituent particles from excitonic transition measurements. arXiv:1909.04906v1 [cond-mat.mes-hall]

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“…The whole method is detailed in Ref. [26]. We consider here the exchange interaction up to second order of the multipole expansion [27,28].…”

Section: Calculation Of Anisotropic Exchange Energymentioning

confidence: 99%

Optical orientation and alignment of excitons in direct and indirect band gap (In,Al)As/AlAs quantum dots with type-I band alignment

et al. 2019

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The spin structure and spin dynamics of excitons in an ensemble of (In,Al)As/AlAs quantum dots (QDs) with type-I band alignment, containing both direct and indirect band gap dots, are studied. Time-resolved and spectral selective techniques are used to distinguish between the direct and indirect QDs. The exciton fine structure is studied by means of optical alignment and optical orientation techniques in magnetic fields applied in the Faraday or Voigt geometries. A drastic difference in emission polarization is found for the excitons in the direct QDs involving a Γ-valley electron and the excitons in the indirect QDs contributed by an X-valley electron. We show that in the direct QDs the exciton spin dynamics is controlled by the anisotropic exchange splitting, while in the indirect QDs it is determined by the hyperfine interaction with nuclear field fluctuations. The anisotropic exchange splitting is determined for the direct QD excitons and compared with model calculations.c is the maximal circular polarization degree achieved in strong fields, µ B is the Bohr magneton, and g ex is the longitudinal exciton g-factor. The latter is composed of the Γ-electron (g e ) and heavy hole (g hh ) gfactors: g ex = g hh − g e . Both dependencies of ρ l (B) and

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Excitonic structure and pumping power dependent emission blue-shift of type-II quantum dots

Cited by 39 publications

References 57 publications

Optical response of (InGa)(AsSb)/GaAs quantum dots embedded in a GaP matrix

Optical response of (InGa)(AsSb)/GaAs quantum dots embedded in a GaP matrix

Single-particle-picture breakdown in laterally weakly confining GaAs quantum dots

Optical orientation and alignment of excitons in direct and indirect band gap (In,Al)As/AlAs quantum dots with type-I band alignment

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