Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 57: Ultrafast Electron Dynamics I
O 57.9: Vortrag
Mittwoch, 19. März 2025, 12:45–13:00, H2
Formation and thermalization of non-equilibrium excitonic occupations — •Paul Werner1, Jan P. Bange1, Wiebke Bennecke1, Giuseppe Meneghini2, David Schmitt1, Marco Merboldt1, Anna Seiler1, AbdulAziz AlMutairi3, Samuel Brem2, Junde Liu1, Daniel Steil1, Stephan Hofmann3, R. Thomas Weitz1, Ermin Malic2, Stefan Mathias1, and Marcel Reutzel1 — 1I. Physikalisches Institut, Georg-August Universität Göttingen, Germany — 2Fachbereich Physik, Philipps-Universität Marburg, Germany — 3Department of Engineering, University of Cambridge, United Kingdom
Semiconducting transition metal dichalcogenides (TMDs) host a rich landscape of Coulomb-correlated electron-hole pairs, which makes them ideal candidates for future optoelectronic applications. After an initial optical excitation of bright excitons, it is known that subsequent scattering into optically dark excitons takes place [1]. However, these processes must involve non-thermal exciton distributions that thermalize to a quasi-equilibrium [2]. In this work we use time-resolved momentum microscopy to directly access these non-thermal exciton distributions in optically excited homobilayer MoS2. We identify the exciton landscape and relaxation pathways, and we find clear signatures of the non-equilibrium exciton distributions that are involved in the thermalization process. We compare our data with a full microscopic model calculation that confirms our experimental findings.
[1] Bange et al., 2D Materials 10 035039 (2023)
[2] Rosati et al., ACS Photonics 7, 2756–2764 (2020)
Keywords: momentum microscopy; excitons; ultrafast dynamics; transition-metal dichalcogenides; dark excitons