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1
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Many-Electron Effects in Low-Dimensional Semiconductor Structures

100%
Hawrylak P.
Acta Physica Polonica A
|
1995
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vol. 87
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issue 1
67-77
EN
Many-electron effects in low-dimensional semiconductor structures: quan­tum wells, wires, and dots are discussed. Three examples are given: (a) the quasi-particles of a Fermi liquid are illustrated with the calculation of the self-energy of a hot electron coupled to plasmons and optical phonons in modulation doped quantum wells, (b) the Fermi edge singularity and (c) the incompressible states of strongly correlated electrons in quantum dots tunable by applied magnetic field.
2
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Electronic Shells of Dirac Fermions in Graphene Quantum Rings in a Magnetic Field

51%
Potasz P., Güçlü A., Hawrylak P.
Acta Physica Polonica A
|
2009
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vol. 116
|
issue 5
832-834
EN
We present results of tight binding calculations demonstrating existence of degenerate electronic shells of Dirac fermions in narrow, charge neutral graphene quantum rings. We predict removal of degeneracy with finite magnetic field. We show, using a combination of tight binding and configuration interaction methods, that by filling a graphene ring with additional electrons this carbon based structure with half-filled shell acquires a finite magnetic moment.
3
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Interacting Electrons and Holes in Quasi-2D Quantum Dots in Strong Magnetic Fields

51%
Hawrylak P., Sheng W., Cheng S.
Acta Physica Polonica A
|
2004
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vol. 106
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issue 3
403-412
EN
Theory of optical properties of interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields is discussed. In two dimensions and the lowest Landau level, hidden symmetries control the interaction of the interacting system with light. By confining electrons and holes into quantum dots hidden symmetries can be removed and the excitation spectrum of electrons and excitons can be observed. We discuss a theory electronic and of excitonic quantum Hall droplets at a filling factorν=2. For an excitonic quantum Hall droplet the characteristic emission spectra are predicted to be related to the total spin of electron and hole configurations. For the electronic droplet the excitation spectrum of the droplet can be mapped out by measuring the emission for increasing number of electrons.
4
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Many-Exciton Complexes in Self-Assembled Quantum Dots

51%
Wójs A., Hawrylak P., Jacak L.
|
EN
The system of interacting electrons and holes confined in a lens-shaped InGaAs self-assembled dot is studied using exact diagonalization techniques. The single-particle energy spectrum of self-assembled dot is well approximated by that of a quasi-two-dimensional atom with parabolic lateral confinement. The electronic shell structure of self-assembled dot is responsible for a remarkable dependence of the absorption/emission spectrum on the number of excitons. This is explained in terms of hidden symmetries leading to a formation of coherent many-exciton states of weakly interacting excitons and bi-excitons.
5
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Spectroscopy of Charged Donors and Many-Electron Effects in Semiconductor Quantum Wells

45%
McCombe B., Jiang Z., Tischler J., Weinstein B., Hawrylak P.
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vol. 96
|
issue 5
559-572
EN
Far infrared magnetospectroscopic studies of negative donor ions (D^{-}), and donors in the presence of many excess electrons in high magnetic fields in GaAs/AlGaAs quantum wells are reviewed. Both singlet and triplet transitions of well-center D^{-}ions were observed and are in good agreement with recent theoretical calculations. For off-well-center D^{-}ions evidence for a predicted magnetic-field-induced "unbinding" of the second electron was found. In the presence of many excess electrons the D^{-}singlet and -triplet transitions are blue-shifted substantially and evolve into bound magnetoplasmon excitations. Cusps are observed at integral and fractional Landau-level filling factors (ν) in a plot of normalized blue-shift of the D^{-}singlet-like bound magnetoplasmon transition vs. ν. For ν<1, the singlet-like bound magnetoplasmon transition continuously approaches the isolated D^{-}singlet transition with increasing magnetic field, while the triplet-like transition loses strength, irrespective of the electron density. Exact diagonalization studies of a donor ion with a few electrons in a parabolic lateral confining potential show the importance of electron-electron interactions and localization due to the long-range fluctuating potential in explaining this behavior. High pressure studies in a specially designed diamond anvil cell exhibit a continuous evolution from bound magnetoplasmon transitions to isolated D^{-}transitions to neutral donor transitions in a single sample as the pressure is increased and the electron density in the wells is decreased.
6
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Influence of Configuration Mixing on Energies and Recombination Dynamics of Excitonic States in CdTe/ZnTe Quantum Dots

33%
Smoleński T., Kazimierczuk T., Goryca M., Kossacki P., Gaj J., Wojnar P., Fronc K., Korkusiński M., Hawrylak P.
Acta Physica Polonica A
|
2011
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vol. 119
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issue 5
615-617
EN
We study experimentally and theoretically excitonic recombination processes in CdTe/ZnTe quantum dots. The single quantum dot photoluminescence spectrum was observed and emission lines from X, X^-, X^+ and 2X excitonic states were identified. Experimental results were analysed in the theoretical model based on the effective mass approximation. Numerical calculations of energy positions and recombination probabilities of X, X^-, X^+ and 2X were performed. Computed results reproduce correctly the order and relative positions of emission lines and ratios of radiative lifetimes.
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