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Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 9: Ultrafast Electron Dynamics at Surfaces and Interfaces 2

O 9.11: Talk

Monday, September 5, 2022, 17:30–17:45, H3

SHG imaging microscopy of ultrafast charge-transfer dynamics in twisted TMDC heterostructures — •Marleen Axt, Jonas E. Zimmermann, Gerson Mette, and Ulrich Höfer — Fachbereich Physik, Philipps Universität Marburg, Germany

Two-dimensional heterostructures of transition metal dichalcogenides (TMDC) represent very well-defined model systems of van-der-Waals interfaces. Many material combinations feature a type-II band alignment, which can separate photoexcited electrons and holes into different layers through ultrafast charge transfer leading to the formation of so-called interlayer excitons or interface excitons.

We investigate the ultrafast charge-transfer dynamics in TMDC heterostructures as a function of the stacking angle using time-resolved second-harmonic generation (SHG) imaging microscopy. This experimental technique combines the advantages of SHG with high temporal and spatial resolution. For differently twisted MoS2/WSe2 heterostructures the electron transfer from WSe2 to MoS2 after resonant excitation (1.70 eV) was found to depend considerably on the twist angle. The transfer time is reduced from 85 fs down to 12 fs when going from a larger rotational mismatch (16) towards 2H-stacking (52).

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