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HL: Fachverband Halbleiterphysik

HL 48: Two-dimensional Materials IV (joint session HL/CPP)

HL 48.2: Vortrag

Freitag, 5. April 2019, 09:45–10:00, H36

Exciton-lattice coupling in monolayer WSe2 investigated by femtosecond electron diffraction — •Shuo Dong¹, Daniela Zahn¹, Robert Schneider², Thomas Vasileiadis¹, Helene Seiler¹, Yingpeng Qi¹, Rudolf Bratschitsch², and Ralph Ernstorfer¹ — ¹Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany — ²Institute of Physics and Center for Nanotechnology, University of Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany

Exciton-phonon coupling as the essential exciton relaxation mechanism plays a crucial role in transition metal dichalcogenides (TMDC). Besides the bright exciton dynamics, the formation of dark excitons greatly impacts the optoelectronic properties of atomically thin TMDC, which requires spin flip-scattering or phonon-assisted momentum transfer. Here, we investigate the incoherent lattice excitation associated with exciton relaxation in monolayer WSe2 by femtosecond electron diffraction. We discuss the observed structural dynamics in terms of the intra- and inter-valley exciton scattering towards the lower-lying dark states. The direct measurement of lattice motion provides important complementary insights to exciton dynamics.