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1999 | 96 | 5 | 559-572
Article title

Spectroscopy of Charged Donors and Many-Electron Effects in Semiconductor Quantum Wells

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EN
Abstracts
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.
Keywords
EN
Year
Volume
96
Issue
5
Pages
559-572
Physical description
Dates
published
1999-11
References
Document Type
Publication order reference
YADDA identifier
bwmeta1.element.bwnjournal-article-appv96z505kz
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