Dresden 2020 – scientific programme

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DS: Fachverband Dünne Schichten

DS 11: 2D semiconductors and van der Waals heterostructures II (joint session HL/DS)

DS 11.8: Talk

Monday, March 16, 2020, 17:30–17:45, POT 81

Theory of Exciton-Electron Coupling in Two-Dimensional Semiconductors — •Frederik Schirdewahn¹, Dominik Christiansen¹, Andreas Knorr¹, Tommaso Venanzi², Stephan Winnerl², and Malte Selig¹ — ¹Technische Universität Berlin, Germany — ²Helmholtz Zentrum Dresden-Rossendorf, Germany

The strong Coulomb interaction in monolayers of doped transition metal dichalcogenides (TMDCs) leads to the formation of tightly bound excitons and electron gas assisted exciton transitions (trions)[1,2]. Here we present a microscopic approach within the Heisenberg equation of motion formalism for the excitonic absorption including trion signatures[3]. We discuss the impact of doping density and temperature on the absorption spectrum. Additionally we present a joint experiment theory study for THz pump VIS probe experiments of doped monolayer MoSe₂, where we find a red shift of exciton and trion lines which we trace back to a heating of the electrons due to the THz pulse finding a good comparison between theory and experiment.

[1] G. Plechinger et al., Nat. Commun. 7, 12715 (2016)

[2] T. C. Berkelbach et al., Phys. Rev. B 88, 045318 (2013)

[3] A. Esser et al., phys. stat. sol. (b) 2, 317 (2001)