Exciton-phonon coupling in InP quantum dots with ZnS and (Zn,Cd)Se shells
| Autor: | Mariana V. Ballottin, Jonathan Buhot, Annalisa Brodu, Daniel Vanmaekelbergh, Dorian Dupont, Freddy T. Rabouw, Mickael D. Tessier, Celso de Mello Donegá, Zeger Hens, Peter C. M. Christianen |
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| Rok vydání: | 2020 |
| Předmět: |
Photoluminescence
Phonon Exciton 02 engineering and technology Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 021001 nanoscience & nanotechnology Coupling (probability) 01 natural sciences Molecular physics Condensed Matter::Materials Science Dark state Quantum dot 0103 physical sciences Content (measure theory) Spontaneous emission 010306 general physics 0210 nano-technology |
| Zdroj: | Physical Review B. 101 |
| ISSN: | 2469-9969 2469-9950 |
| Popis: | InP-based colloidal quantum dots are promising for optoelectronic devices such as light-emitting diodes and lasers. Understanding and optimizing their emission process is of scientific interest and essential for large-scale applications. Here we present a study of the exciton recombination dynamics in InP QDs with various shells: ZnS, ZnSe, and (Zn,Cd)Se with different amounts of Cd (5, 9, 12%). Phonon energies extracted from Raman spectroscopy measurements at cryogenic temperatures (4--5 K) are compared with exciton emission peaks observed in fluorescence line narrowing spectra. This allowed us to determine the position of both the bright $F=\ifmmode\pm\else\textpm\fi{}1$ state and the lowest dark $F=\ifmmode\pm\else\textpm\fi{}2$ state. We could identify the phonon modes involved in the radiative recombination of the dark state and found that acoustic and optical phonons of both the core and the shell are involved in this process. The Cd content in the shell increases electron wave-function delocalization, and thereby enhances the exciton-phonon coupling through the Fr\"ohlich interaction. |
| Databáze: | OpenAIRE |
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