Regensburg 2022 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 7: 2D Materials 2 (joint session HL/CPP/DS)

DS 7.4: Vortrag

Montag, 5. September 2022, 15:45–16:00, H36

Dark and bright exciton dynamics probed by time-resolved photoluminescence in hBN-encapsulated MoWSe₂ monolayers — •Julian Schröer^{1, 3}, Joanna Kutrowska-Girzycka², Leszek Bryja², Joanna Jadczak², and Jörg Debus¹ — ¹TU Dortmund, Experimentelle Physik 2, AG Debus — ²Wroclaw University of Science and Technology, Department of Experimental Physics — ³Universität Rostock, Institut für Physik, AG Korn: Zweidimensionale Kristalle und Heterostrukturen

Semiconducting monolayers of ternary MoWSe₂ alloys combine the unique properties of the binary transition metal dichalcogenide (TMDC) materials MoSe₂ and WSe₂. The alloying leads to, for example, brightening of the momentum- and spin-forbidden dark exciton states. Detailed studies on the dynamics of these brightened dark states are missing. We report on the exciton and trion formation lying in the 1-3 ps range, while the decay time approaches hundreds picoseconds. Additionally, strong dependences on the temperature and exciting laser light polarization are observed. In time-resolved and stationary photoluminescence measurements, we reveal the impact of the crystal disorder potential on the exciton properties. The polarization dynamics of the exciton and trion photoluminescence indicate possible contributions from chiral phonons as well as electrons and holes from different valleys of the Brillouin zone. Our work is a further step towards a deeper understanding of the dynamics of dark excitons in TMDC materials.