Dresden 2020 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 21: Layer Properties I: Electronic Properties

DS 21.4: Vortrag

Mittwoch, 18. März 2020, 10:15–10:30, CHE 91

Orbital- and thickness dependent band engineering of WSe2 by potassium surface functionalization — •Tom Klaproth1, Carsten Habenicht1, Roman Schuster1, Bernd Büchner1,2, Martin Knupfer1, and Andreas Koitzsch11Leibniz Institute for Solid State and Materials Research, Helmholtzstrasse 20, 01069 Dresden, Germany — 2Institute of Solid State Physics, TU Dresden, 01069 Dresden, Germany

Atomically thin transition metal dichalcogenides (TMDC) are promising candidates for implementation in next generation semiconducting devices, for which effective methods of property engineering are urgently needed. Alkali metal deposition is an important tool to tune the electronic properties of TMDCs and 2D materials in general. Here, by applying angle-resolved photoemission, electron-energy loss spectroscopy and density functional theory, we monitor how exactly potassium deposition alters the electronic structure of WSe2, a prototypical TMDC with large spin-orbit coupling. We find that the changes of the electronic structure are more complex than previously anticipated.

There are two main features: i) The bandstructure shifts down on a thickness dependent rate, implying effective electron delocalization. ii) The density of selenium vs tungsten states depends on the doping level, which leads to changes of the optical response beyond increased dielectric screening. Our work gives detailed insight into the effects of potassium deposition on WSe2, provides microscopic understanding thereof and improves the basis for property engineering of 2D materials.

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