Dresden 2017 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 63: Poster: Quantum Dots and Optics
HL 63.65: Poster
Mittwoch, 22. März 2017, 15:00–19:00, P1A
Magneto-optical study to reveal the exciton fine structure in InP/ZnSe core/shell quantum dots. — •Annalisa Brodu1, Mariana Ballottin2, Dorian Dupont3, Zeger Hens3, Peter C. M. Christianen2, Celso de Mello Donega1, and Daniel Vanmaekelbergh1 — 1Debye Institute for Nanomaterials Science, Utrecht University, The Netherlands — 2High Field Magnet Laboratory, IMM, Radboud University, The Netherlands — 3Physics and Chemistry of Nanostructures, Ghent University, Belgium
Colloidal quantum dots (QDs) are of significant interest in nanoscience and opto-electronic applications due to their size-tunable emission spectrum in combination with broad absorption and excitation spectra. For decades, Cd-chalcogenide QDs have been the workhorse in this field. However, application in devices requires toxicologically harmless materials. As a result, the demand for Cd-free colloidal QDs is rising rapidly and therefore the knowledge of the electronic structure of InP-based core/shell QDs is of large interest.
In this work we studied the exciton fine-structure of InP/ZnSe QDs with various core diameters using different techniques: fluorescence line-narrowing spectroscopy, polarized photoluminescence (PL) spectroscopy and time-resolved PL spectroscopy, in high magnetic fields up to 30 T at temperatures down to 4 K. The high magnetic field allowed us to obtain a considerable Zeeman splitting of spin degenerate states and to induce significant mixing of exciton levels with different angular momentum. Combined with detection of the polarization of the emitted photons, the nature of the states has been resolved unambiguously.