Temporal evolution of low-temperature phonon sidebands in WSe$_2$ monolayers
| Autor: | Rosati, Roberto, Brem, Samuel, Perea-Causín, Raül, Wagner, Koloman, Wietek, Edith, Zipfel, Jonas, Selig, Malte, Taniguchi, Takashi, Watanabe, Kenji, Knorr, Andreas, Chernikov, Alexey, Malic, Ermin |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | ACS Photonics 2020, 7, 10, 2756-2764 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1021/acsphotonics.0c00866 |
| Popis: | Low-temperature photoluminescence (PL) of hBN-encapsulated monolayer tungsten diselenide (WSe$_2$) shows a multitude of sharp emission peaks below the bright exciton. Some of them have been recently identified as phonon sidebands of momentum-dark states. However, the exciton dynamics behind the emergence of these sidebands has not been revealed yet. In this joint theory-experiment study, we theoretically predict and experimentally observe time-resolved PL providing microscopic insights into thermalization of hot excitons formed after optical excitation. In good agreement between theory and experiment, we demonstrate a spectral red-shift of phonon sidebands on a timescale of tens of picoseconds reflecting the phonon-driven thermalization of hot excitons in momentum-dark states. Furthermore, we predict the emergence of a transient phonon sideband that vanishes in the stationary PL. The obtained microscopic insights are applicable to a broad class of 2D materials with multiple exciton valleys. Comment: 10 pages, 5 figures |
| Databáze: | arXiv |
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