SKM 2023 – scientific programme

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O: Fachverband Oberflächenphysik

O 19: Poster: Ultrafast Electron Dynamics at Surface and Interfaces I

O 19.9: Poster

Monday, March 27, 2023, 18:00–20:00, P2/EG

Ultrafast dynamics of CT excitons in 2d heterostructures investigated with SHG imaging microscopy — •Marleen Axt, Jonas E. Zimmermann, Gerson Mette, and Ulrich Höfer — Fachbereich Physik, Philipps-Universität Marburg, Germany

The exciton dynamics in vertically stacked TMDC heterostructures can be modified by variation of the twist angle between the two layers. Using time-resolved second hamornic (SH) imaging microscopy we observe the ultrafast formation of charge transfer (CT) excitons in micrometer-sized MoS₂/WSe₂ heterostructures with different stacking angles. We make use of the strong anisotropy of the nonlinear SH response to selectively probe the carrier dynamics in individual layers of the system. For misaligned layers with a stacking angle of 16^∘ the formation of CT excitons takes place within 85 fs after resonant excitation of the WSe₂ A excition. In contrast, an alignment close to 2H stacking (52^∘) leads to an enhanced electronic coupling between the layers resulting in a much faster CT exciton formation time of only 12 fs. Moreover, different formation and relaxation pathways are identified depending on the pump-photon energy.