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DS: Fachverband Dünne Schichten
DS 19: 2D semiconductors and van der Waals heterostructures IV (joint session HL/DS/O)
DS 19.1: Vortrag
Dienstag, 17. März 2020, 14:00–14:15, POT 81
Resolving the interlayer charge transfer in van der Waals heterostructures by ultrafast THz emission nanoscopy — •Markus Plankl1, Martin Zizlsperger1, Fabian Mooshammer1, Felix Schiegl1, Fabian Sandner1, Markus A. Huber1, Tom Siday1, Jessica L. Boland2, Tyler L. Cocker3, and Rupert Huber1 — 1Department of Physics, University of Regensburg, 93053 Regensburg, Germany — 2Photon Science Institute, University of Manchester, Manchester M13 9PL, UK — 3Department of Physics and Astronomy, Michigan State University, 48824 Michigan, USA
In van der Waals heterostructures composed of two transition metal dichalcogenide monolayers, photogenerated electron-hole pairs are spatially separated on ultrafast timescales, giving rise to the formation of interlayer excitons. Yet, the underlying interlayer charge transfer has only been investigated in a spatially averaged manner. Consequently, probing nanoscale transfer efficiencies and tunneling rates has so far remained elusive. Since the tunneling of photoexcited charge carriers between adjacent layers represents an ultrafast current along the out-of-plane direction, a concomitant electromagnetic pulse in the terahertz spectral range is emitted. By combining electro-optic time-domain spectroscopy with near-field microscopy, we resolve this characteristic fingerprint of the interlayer carrier dynamics on the nanoscale with sub-cycle temporal resolution. Thereby, we infer tunneling characteristics, which we relate with the nanoscale conductivity of the heterostructure.