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We have investigated charge tunable devices based on WSe2 and WS2 monolayers encapsulated in hexag- onal boron nitride. In addition to the well-known radiative recombination of neutral and charged excitons, stationary photoluminescence measurements highlight a weaker-intensity optical transition that appears when the monolayer is electrostatically doped with electrons. We have carried out a detailed characterization of this photoluminescence line based on its doping dependence, its variation as a function of the optical excitation power, its polarization characteristics, and its g factor measured under longitudinal magnetic field. We interpret this luminescence peak as an impurity-assisted radiative recombination of the intervalley negatively charged exciton (triplet trion). In addition to the standard direct recombination, the triplet trion has a second recom- bination channel triggered by elastic scattering off the short-range impurity potential. The energy difference between the emitted photons from these two possible recombination processes of the same triplet trion is simply the single-particle conduction band spin-orbit splitting Dc . We measure Dc = 12 ± 0.5 meV for the WSe2 monolayer and Dc = 12 ± 1 meV for the WS2 monolayer. These results demonstrate the importance of second-order exciton recombination processes in transition-metal dichalcogenide structures.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Gate-defined quantum confined channels, conductance quantization, transition metal dichalcogenide

刊行年月日: 2023-07-15

出版者: Springer Science and Business Media LLC

掲載誌:

• npj 2D Materials and Applications (ISSN: 23977132) vol. 7 issue. 1 50

研究助成金:

• Gouvernement du Canada | National Research Council Canada QSP

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1038/s41699-023-00407-y

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更新時刻: 2025-02-23 22:47:42 +0900

MDRでの公開時刻: 2025-02-23 22:47:42 +0900