Dresden 2020 – scientific programme
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DS: Fachverband Dünne Schichten
DS 29: Poster: 2D Materials and their Heterostructures
DS 29.7: Poster
Wednesday, March 18, 2020, 15:00–18:00, P1A
Electron and exciton phonon interaction in gate tunable TMDC layers — •David O. Tiede1, Hendrik Lambers1, Margaux Lassaunière1, Katharina Nisi2, and Ursula Wurstbauer1 — 1Institute of Physics, University of Münster, Germany — 2Walter Schottky Institute and Physics Department, Technical University of Munich, Garching, Germany
Semiconducting transition metal dichalcogenides are a class of 2D materials of great interest because of their unique properties such as valley selective optical excitation or phonon-mediated multi-valley superconductivity. Phonons are a significant mechanism for valley depolarization at elevated temperatures. We observe a significant coupling between the long-range oscillating electric field induced by the longitudinal optical (LO) phonon. This Fröhlich exciton LO-phonon interaction [1] is suppressed by doping and correlates with a distinct increase of the degree of valley polarization of up to 60 % even at elevated temperatures of 220 K [1]. Higher-doping is expected to turn the system to superconducting phase at low temperatures [2]. We study the electrical and optical response of gate tunable TMDC flakes by combined spectroscopic imaging ellipsometer, charge transport and Raman measurements.
[1] B. Miller et al. Nature Commun. 10, 807 (2019). [2] E. Piatti et al. Nano Lett. 18, 8, 4821-4830 (2018).