Inverse exciton spin orientation due to trion formation in modulation doped quantum wells

Time-resolved and time-integrated circularly polarized photoluminescence of excitons and trions in external magnetic fields up to 10 T has been studied in undoped and n-type doped quantum well structures based on ZnSe. In an undoped structure, a circular polarization of photoluminescence induced by...

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Bibliographic Details
Published in:arXiv.org 2023-10
Main Authors: Kotova, Lyubov, Platonov, Alexei, Kochereshko, Vladimir
Format: Article
Language:English
Subjects:
Boltzmann distribution
Carrier density
Circular polarization
Electric fields
Excitons
Magnetic fields
Orientation
Photoluminescence
Quantum wells
Trions
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Summary:Time-resolved and time-integrated circularly polarized photoluminescence of excitons and trions in external magnetic fields up to 10 T has been studied in undoped and n-type doped quantum well structures based on ZnSe. In an undoped structure, a circular polarization of photoluminescence induced by magnetic fields corresponded to the Boltzmann distribution of excitons on Zeeman sublevels. The inverse spin orientation of excitons is observed in doped samples with a carrier density of \(3 \times 10^{10}\) cm\(^{-2}\) and higher. Model calculations show that the reason for the inverse spin orientation is the effective depletion of the lowest-exciton Zeeman sublevel as a result of the spin-dependent formation of trions. The trion formation time as a result of exciton-electron binding was determined as 2 ps. This is noticeably shorter than the characteristic time of the exciton-photon interaction. The observed effect can be considered as a way of spin manipulation by electric fields.
ISSN:2331-8422
DOI:10.48550/arxiv.2310.06651