Optical orientation and alignment of excitons in direct and indirect band gap (In,Al)As/AlAs quantum dots with type-I band alignment
| Autor: | Petr Klenovský, J. Rautert, S. V. Nekrasov, Dmitri R. Yakovlev, Manfred Bayer, Yu. G. Kusrayev, T. S. Shamirzaev |
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| Rok vydání: | 2019 |
| Předmět: |
OPTICAL ORIENTATION
Materials science Exciton FOS: Physical sciences Physics::Optics ENERGY GAP SPIN FLUCTUATIONS ANISOTROPIC EXCHANGE SPLITTING 02 engineering and technology Electron Spin structure 01 natural sciences Molecular physics Condensed Matter::Materials Science Mesoscale and Nanoscale Physics (cond-mat.mes-hall) 0103 physical sciences TYPE I BAND ALIGNMENTS 010306 general physics Hyperfine structure ANISOTROPY Quantum Physics Condensed Matter - Mesoscale and Nanoscale Physics OPTICAL ALIGNMENTS Condensed Matter::Other EXCITONS EXCITON FINE STRUCTURE Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 021001 nanoscience & nanotechnology Polarization (waves) Magnetic field HYPERFINE INTERACTIONS NANOCRYSTALS EXCITON SPIN DYNAMICS Quantum dot MODEL CALCULATIONS Direct and indirect band gaps SEMICONDUCTOR QUANTUM DOTS Quantum Physics (quant-ph) 0210 nano-technology |
| Zdroj: | Phys. Rev. B Physical Review B |
| ISSN: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.99.195411 |
| Popis: | 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. © 2019 American Physical Society. |
| Databáze: | OpenAIRE |
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