Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 29: Poster II
HL 29.13: Poster
Tuesday, March 18, 2025, 18:00–20:00, P1
Moiré superlattice effects in MoSe2-WS2 heterobilayers — •P. Parzefall1, N. Paulik1, M. Lorenz1, C. Serati de Brito1,2, J. Göser3, J. Trapp3, T. Taniguchi4, K. Watanabe4, A. Högele3, Y. Galvão Gobato2, and C. Schüller1 — 1Institut für Exp. und Angewandte Physik, Uni Regensburg (UR), Germany — 2Physics Department, Federal University of São Carlos, Brazil — 3Faculty of Physics, Munich Quantum Center and Center for NanoScience, LMU Munich, Germany — 4NIMS, Tsukuba Ibaraki, Japan
We report about optical studies on type-I MoSe2-WS2 heterostructures at cryogenic temperatures. We confirm the influence of the moiré superlattice on excitonic features of angle aligned R- and H-type structures in photoluminescence spectroscopy. The moiré-exciton and moiré-trion features are further studied by resonant low-frequency Raman spectroscopy. Here, we tune a Ti:Sapphire laser into close resonance to the MoSe2 intralayer excitonic transitions. We detect an efficient pumping of the moiré trion when exciting resonantly to the moiré exciton, as the binding energy is equivalent to a phonon energy.
In time-resolved measurements using a Streak camera, we measure the lifetimes of both H-type and R-type moiré-excitonic species. The detected short excitonic lifetimes in the R-type sample is indicative of a type-I band alignment and the longer moiré-exciton lifetimes in the H-type samples might be due to a hybridization in the conduction bands [1, 2]. [1] B. Polovnikov et al., Phys. Rev. Lett. 132, 076902 (2024), [2] Y. Galãvo Gobato et al., Nano Lett. 22, 8641 (2022)
Keywords: moiré; heterostructure; hybridization; type-I band alignment