Dresden 2017 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 14: 2D Materials Beyond Graphene II (jointly with CPP)
DS 14.6: Vortrag
Montag, 20. März 2017, 17:15–17:30, REC/PHY C213
Electrostatically tuned 2D Heterostructures — •Christian Winkler, Shashank S. Harivyasi, and Egbert Zojer — Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
The family of two-dimensional (2D) materials has been growing rapidly since the discovery of graphene. This creates new scientific challenges as well as opportunities because the properties of layered, van der Waals bonded systems are often different from their 3D counterparts, which offers entirely new strategies for band-structure engineering.
In this work, using first principles approaches, we propose a novel strategy for engineering the level alignment in van der Waals heterostructures. In particular, we focus on the inclusion of self-assembling polar molecules (e.g. Titanyl phthalocyanine) into stacks consisting of 2D transition metal dichalcogenides (TMDCs) sheets (MoX2 and WX2, where X = S or Se). For structures of the type TMDC/TiOPc/TMDC we observe a shift in the frontier levels of successive TMDC layers by as much as 0.4 eV. Remarkably, for WSe2/TiOPc/MoS2 this allows switching between type I and type II alignment. Using multiple TiOPc layers even quantum cascades can be realized.
Beyond that, we aim to explore the interplay between strain applied to the individual layers (which is known to induce direct to indirect gap transitions) and the electrostatic design approach.