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O: Fachverband Oberflächenphysik

O 8: Ultrafast Electron Dynamics I: Surfaces and Interfaces (joint session O/MA)

O 8.4: Vortrag

Montag, 16. März 2020, 11:15–11:30, TRE Phy

Ultrafast hole-transfer in MoSe₂/WSe₂ revealed by polarisation dependent second-harmonic imaging microscopy — •Jonas Zimmermann, Ulrich Höfer, and Gerson Mette — Fachbereich Physik, Philipps-Universität Marburg, Germany

Charge transfer across heterointerfaces plays a fundamental role for the functionality of electronic devices. 2D heterostructures based on transition metal dichalcogenides (TMDC) with their wide variety of materials and stacking combinations represent a unique opportunity for systematic studies of the interfacial charge-carrier dynamics.

Here, we present results on a MoSe₂/WSe₂ heterostructure investigated by time-resolved second-harmonic (SH) imaging microscopy. The transient SH-response after resonant optical excitation reveals a delayed filling and an enhanced lifetime for the heterostructure which is absent for the individual monolayers, indicating the formation of interlayer excitons. By careful selection of the polarisation of the probe laser, we are able to enhance the sensitivity to the individual layers in the heterostructure and with that to the charge transfer. Systematic measurements in dependence of the pump photon energy and the probe polarisation exhibit temporal signatures which are attributed to hole transfer from WSe₂ to MoSe₂ and vice versa with transfer times of a few hundred femtoseconds in both cases.