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O: Fachverband Oberflächenphysik

O 120: Focus Session: Nonequilibrium Electron Transfer Across Interfaces in Real Time

O 120.1: Hauptvortrag

Freitag, 20. März 2020, 10:30–11:00, TRE Ma

Ultrafast charge transfer dynamics in 2D heterostructures — •Giulio Cerullo, Stefano Dal Conte, Zilong Wang, and Chiara Trovatello — Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy

In the last few years, the research on 2D materials has developed towards the engineering and realization of new heterostructures (HS) based on stacking two or more 2D crystals on top of each other. In such HSs, the electronic structure of the single layers is well retained because of the weak interlayer van der Waals coupling. Nevertheless, new physical properties and functionalities, depending on the type and the stacking sequence of layers, arise beyond their constituent blocks. These new HS have high potential in the field of flexible optoelectronics because they combine strong light matter interaction, high flexibility and high charge carrier mobility. The experimental study of the interlayer charge scattering process in such HS is of paramount importance for developing 2D HS-based optoelectronic devices. In this work we use optical pump-probe spectroscopy to study photoinduced charge transfer dynamics in two different 2D HS: a TMDs heterobilayer (WSe2/MoSe2) and a graphene/WS2 HS. We resolve interlayer exciton formation (200-fs) and decay dynamics in WSe2/MoSe2. We also monitor photothermoionic charge transfer dynamics from graphene to WS2 when pumped well below the semiconductor bandgap, due to hot carriers injection across the HS Schottky barrier.