2019/04/18 by Janina Rautert, J. Rautert, T. S. Shamirzaev +7 · 30 citations
Engineering · Materials Science · Mathematics · Physics and Astronomy · #Advanced Semiconductor Detectors and Materials #Band gap #Condensed matter physics #Direct and indirect band gaps #Exciton #Geometry #Materials science #Mathematics #Optoelectronics #Orientation (vector space) #Physics #Quantum #Quantum Dots Synthesis And Properties #Quantum dot #Quantum mechanics #Semiconductor Quantum Structures and Devices #cond-mat.mes-hall #quant-ph
paper · pdf · doi:10.1103/physrevb.99.195411
published in Physical review. B./Physical review. B 99(19) (American Physical Society)
arxiv created 2019/04/18 · openalex publication_date 2019/05/08 · arxiv updated 2019/05/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 \mathrm\ensuremathΓ-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.