Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 47: 2D Materials: Heterostuctures
HL 47.4: Vortrag
Donnerstag, 21. März 2024, 15:45–16:00, EW 201
Distance dependence of the energy transfer mechanism in WS2-graphene heterostructures — •David Tebbe1, Marc Schütte1, Kenji Watanabe2, Takashi Taniguchi3, Christoph Stampfer1, Bernd Beschoten1, and Lutz Waldecker1 — 12nd Institute of Physics A, RWTH Aachen University, Aachen, Germany — 2Research Center for Functional Materials, National Institute for Materials Science, Japan — 3International Center for Materials Nanoarchitectonics, Japan
We investigate the mechanism of energy transfer in heterostructures of the two-dimensional semiconductor WS2 and graphene with variable interlayer distances achieved through spacer layers of hexagonal boron nitride (hBN). Our analysis of the emission and absorption line widths reveals that the energy transfer is dominated by states outside the light cone, indicating a Förster transfer process. The dependence of luminescence intensity on interlayer distances above 1 nm can be quantitatively reproduced using recently calculated values of the Förster transfer rates of thermalized charge carriers and a constant radiative rate. However, at smaller interlayer distances, the experimentally observed transfer rates exceed the predictions and depend on excess energy and excitation density. We conclude that at these distances, the transfer is driven by non-thermalized charge carrier distributions, as the transfer probability of the Förster mechanism depends on the momentum of electron-hole pairs.
Keywords: TMDc; 2D materials; Energy transfer; Photoluminescence spectroscopy; Heterostructures