• Medientyp: E-Artikel
  • Titel: Unveiling Valley Lifetimes of Free Charge Carriers in Monolayer WSe 2
  • Beteiligte: Ersfeld, Manfred [VerfasserIn]; Volmer, Frank [VerfasserIn]; Shi, Jing [VerfasserIn]; Stampfer, Christoph [VerfasserIn]; Beschoten, Bernd [VerfasserIn]; Rathmann, Lars [VerfasserIn]; Kotewitz, Luca [VerfasserIn]; Heithoff, Maximilian [VerfasserIn]; Lohmann, Mark [VerfasserIn]; Yang, Bowen [VerfasserIn]; Watanabe, Kenji [VerfasserIn]; Taniguchi, Takashi [VerfasserIn]; Bartels, Ludwig [VerfasserIn]
  • Erschienen: ACS Publ., 2020
  • Erschienen in: Nano letters 20(5), 3147 - 3154 (2020). doi:10.1021/acs.nanolett.9b05138
  • Sprache: Englisch
  • DOI: https://doi.org/10.1021/acs.nanolett.9b05138
  • ISSN: 1530-6992; 1530-6984
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  • Beschreibung: We report on nanosecond-long, gate-dependent valley lifetimes of free charge carriers in monolayer WSe2, unambiguously identified by the combination of time-resolved Kerr rotation and electrical transport measurements. While the valley polarization increases when tuning the Fermi level into the conduction or valence band, there is a strong decrease of the respective valley lifetime consistent with both electron-phonon and spin-orbit scattering. The longest lifetimes are seen for spin-polarized bound excitons in the band gap region. We explain our findings via two distinct, Fermi-level-dependent scattering channels of optically excited, valley-polarized bright trions either via dark or bound states. By electrostatic gating we demonstrate that the transition-metal dichalcogenide WSe2 can be tuned to be either an ideal host for long-lived localized spin states or allow for nanosecond valley lifetimes of free charge carriers (>10 ns).
  • Zugangsstatus: Freier Zugang