Regensburg 2022 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 25: Poster 1

HL 25.9: Poster

Mittwoch, 7. September 2022, 18:00–20:00, P2

Signature of lattice dynamics in twisted 2D homo/hetero-bilayers — •Yang Pan1,2, Shutong Li3, Mahfujur Rahaman1,2, Ilya Milekhin1,2, and Dietrich R. T. Zahn1,21Semiconductor Physics, Institute of Physics, Chemnitz University of Technology, Chemnitz, Germany — 2Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Chemnitz, Germany — 3Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA

Twisted 2D bilayer materials are created by artificial stacking of two monolayer crystal networks of 2D materials with a desired twisting angle θ. The material forms a moiré superlattice due to the periodicity of both top and bottom layer crystal structure. The optical properties are modified by lattice reconstruction and phonon renormalization, which makes optical spectroscopy an ideal characterization tool to study novel physics phenomena. Here, we report a Raman investigation on a full period of the twisted bilayer (tB) WSe2 moiré superlattice (i.e. 0 ≤ θ ≤ 60). We observe that the intensity ratio of two Raman peaks, B2g and E2g/A1g correlates with the evolution of moiré period. Using a series of temperature-dependent Raman and photoluminescence (PL) measurements as well as ab initio calculations, the intensity ratio IB2g/IE2g/A1g is explained as a signature of lattice dynamics in tB WSe2 moiré superlattices. By further exploring different material combinations of twisted hetero-bilayers, the results are extended for all kinds of Mo- and W-based TMDCs.

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