Valley lifetimes of conduction band electrons in monolayer WSe2

Manfred Ersfeld; Frank Volmer; Lars Rathmann; Luca Kotewitz; Maximilian Heithoff; Mark Lohmann; Bowen Yang; Kenji Watanabe; Takashi Taniguchi; Ludwig Bartels; Jing Shi; Christoph Stampfer; Bernd Beschoten

doi:10.1117/12.2567652

20 August 2020 Valley lifetimes of conduction band electrons in monolayer WSe₂

Manfred Ersfeld, Frank Volmer, Lars Rathmann, Luca Kotewitz, Maximilian Heithoff, Mark Lohmann, Bowen Yang, Kenji Watanabe, Takashi Taniguchi, Ludwig Bartels, Jing Shi, Christoph Stampfer, Bernd Beschoten

Author Affiliations +

Proceedings Volume 11470, Spintronics XIII; 114702M (2020) https://doi.org/10.1117/12.2567652
Event: SPIE Nanoscience + Engineering, 2020, Online Only

Abstract

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 WSe₂. 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 gatedependent valley dynamics.

Citation Download Citation

Manfred Ersfeld, Frank Volmer, Lars Rathmann, Luca Kotewitz, Maximilian Heithoff, Mark Lohmann, Bowen Yang, Kenji Watanabe, Takashi Taniguchi, Ludwig Bartels, Jing Shi, Christoph Stampfer, and Bernd Beschoten "Valley lifetimes of conduction band electrons in monolayer WSe₂", Proc. SPIE 11470, Spintronics XIII, 114702M (20 August 2020); https://doi.org/10.1117/12.2567652

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