Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 19: 2D Materials Beyond Graphene II
O 19.1: Vortrag
Montag, 20. März 2017, 16:00–16:15, REC/PHY C213
2d Heterojunctions From Non-Local Manipulation of the Interactions: Single and Two-Particle Properties — •Christina Steinke1,2, Daniel Mourad1,2, Malte Rösner1,2, Michael Lorke1, Christopher Gies1, Frank Jahnke1, Gerd Czycholl1, and Tim Oliver Wehling1,2 — 1ITP, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany — 2BCCMS, Universität Bremen, Am Fallturm 1a, 28359 Bremen, Germany
In modern optoelectronics heterojunctions are central building blocks of various applications, which commonly rely on interfaces of different materials. Here, we propose a novel scheme to induce heterojunctions within a single homogeneous layer of a two dimensional (2d) material based on Coulomb-interaction effects. Therefore we make use of the fact that in 2d semiconductors the Coulomb interaction can modify band gaps on an eV scale and can be drastically manipulated by external screening. This allows to spatially control the band gap by structured dielectric surroundings. We provide a proof of principle by combining a real-space tight-binding description with a many-body formalism for a model system emulating transitionmetal dichalcogenides. We find sizeable spatial band-gap modulations yielding type-II heterojunctions as needed for solar cells or quantum dots and present detailed insights into their excitation-induced two-particle properties. Utilizing the Bethe-Salpeter equation we show that Rydberg-like higher excitonic states can be strongly tuned by the dielectric surroundings. This effect may be used for efficient trapping of these excitonic states upon tailoring of the environment.