SKM 2023 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 22: 2D Materials IV (joint session HL/CPP)
HL 22.5: Talk
Wednesday, March 29, 2023, 10:45–11:00, POT 81
Tailoring Coulomb interactions 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 — 2Research Center for Functional Materials, Japan — 3International Center for Materials Nanoarchitectonics, Japan
The exciton binding energy and the quasiparticle bandgap in two dimensional semiconductors depend on their dielectric environment.
We investigate the screening of Coulomb interactions in heterostructures of WS2 and graphene, separated through thin spacer layers of hexagonal boron nitride (hBN). By using hBN spacers from one to 16 atomic layers, we experimentally determine the tuning of the exciton binding energy and the quasiparticle bandgap as a function of the WS2-to-graphene interlayer spacing.
This change in both energies is well described by a one over distance dependence, which is consistent with a screening arising from an image charge induced by the graphene layer.
Additionally, by doping the graphene with a graphitic back gate, we show that the ability of the graphene to screen Coulomb interactions in neighbouring layers is strongly modified. We determine the change in screening strength to be approximately 20% at room temperature, demonstrating that Coulomb-interactions in WS2 can be modified in-situ without changing the doping level of the material itself.