Valley lifetimes of conduction band electrons in monolayer WSe$_2$
| Autor: | Ersfeld, Manfred, Volmer, Frank, Rathmann, Lars, Kotewitz, Luca, Heithoff, Maximilian, Lohmann, Mark, Yang, Bowen, Watanabe, Kenji, Taniguchi, Takashi, Bartels, Ludwig, Shi, Jing, Stampfer, Christoph, Beschoten, Bernd |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Spintronics XIII 11470, 114702M (2020) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1117/12.2567652 |
| Popis: | One of the main tasks in the investigation of 2-dimensional transition metal dichalcogenides is the determination of valley lifetimes. In this work, we combine time-resolved Kerr rotation with electrical transport measurements to explore the gate-dependent valley lifetimes of free conduction band electrons of monolayer WSe$_2$. When tuning the Fermi energy into the conduction band we observe a strong decrease of the respective valley lifetimes which is consistent with both spin-orbit and electron-phonon scattering. We explain the formation of a valley polarization by the scattering of optically excited valley polarized bright trions into dark states by intervalley scattering. Furthermore, we show that the conventional time-resolved Kerr rotation measurement scheme has to be modified to account for photo-induced gate screening effects. Disregarding this adaptation can lead to erroneous conclusions drawn from gate-dependent optical measurements and can completely mask the true gate-dependent valley dynamics. Comment: 5 pages, 3 figures |
| Databáze: | arXiv |
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