Dresden 2020 – wissenschaftliches Programm
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DS 29.7: Poster
Mittwoch, 18. März 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  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 . Higher-doping is expected to turn the system to superconducting phase at low temperatures . We study the electrical and optical response of gate tunable TMDC flakes by combined spectroscopic imaging ellipsometer, charge transport and Raman measurements.
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