Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 39: 2D Materials III: Growth and Heterostructures (joint session O/HL)
O 39.12: Talk
Tuesday, March 17, 2020, 13:15–13:30, GER 38
Role of dark trions in the optical response of doped atomically thin semiconductors — •Ashish Arora1, Nils Kolja Wessling1, Thorsten Deilmann1, Till Reichenauer1, Paul Steeger1, Piotr Kossacki2, Marek Potemski2,3, Steffen Michaelis de Vasconcellos1, Michael Rohlfing1, and Rudolf Bratschitsch1 — 1University of Münster, Germany — 2University of Warsaw, Poland — 3Laboratoire National des Champs Magnétiques Intenses, Grenoble, France
We perform absorption and photoluminescence spectroscopy of intravalley and intervalley trions in transition metal dichalcogenide (TMDC) monolayers encapsulated in hBN, depending on temperature [1]. We find that an interplay between the thermal distribution of bright and dark trions, and their oscillator strengths gives rise to the unique optical response of each monolayer material. The observed trends in our experiments are excellently reproduced using a model based on the Fermi-Dirac distribution of bright and dark trions. Our analysis yields that there is a dark trion 19 meV below the lowest energy bright trion in WSe2 and WS2. However, in MoSe2, the dark trion lies 6 meV above the bright trion, while it almost coincides in energy with the bright trion in MoS2. These results are in excellent agreement with our GW-BSE ab-initio calculations of trions for these materials. Our observations provide a quantitative understanding of the temperature-dependent optical response of TMDCs. [1] Preprint at https://arxiv.org/abs/1911.06252