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HL: Fachverband Halbleiterphysik
HL 48: Two-dimensional Materials IV (joint session HL/CPP)
HL 48.1: Talk
Friday, April 5, 2019, 09:30–09:45, H36
Optical Valleytronic Properties of CVD-grown Tungsten Disulfide AA' and AB Bilayers — •Lorenz Maximilian Schneider1, Jan Kuhnert1, Simon Schmitt1, Ulrich Huttner1, Lars Meckbach1, Tineke Strouken1, Stepan W. Koch1, Wolfram Heimbrodt1, Shichen Fu2, Xiaotian Wang2, Kyung Nam Kang2, and Arash Rahimi-Iman1 — 1Faculty of Physics and Materials Sciences Center, Philipps-Universität Marburg, D-35032 Marburg, Germany — 2Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, 07030, USA
Two-dimensional semiconductors such as transition-metal dichalcogenides have attracted considerable attention due to their strong light-matter interaction as well as "valleytronic" properties. The valley-dependent polarization properties are of potential interest for future devices and, both, homojunctions as well as heterostructures of monolayer materials promise considerable valley-polarization degrees and valley coherence.
In this work, chemical-vapour-deposition-grown AA' and AB stacked tungsten-disulfide bilayers are investigated. The differences between AA' and AB stacked bilayers are characterized optically and attributed to the distinct interlayer coupling between k-space valleys. Our spectroscopic investigations are supported by calculations focusing on the difference in symmetry and interlayer electronic coupling for these bilayers. A comparably high valley polarization and valley coherence is found for the AB stacked case in contrast to the AA' case, which is in good agreement with the expectations.