Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 27: 2D semiconductors and van der Waals heterostructures III (joint session HL/DS)
HL 27.7: Talk
Tuesday, March 17, 2020, 11:45–12:00, POT 81
Exciton diffusion in WS2 monolayers with suppressed disorder — •Koloman Wagner1, Jonas Zipfel1, Marvin Kulig1, Raül Perea-Causín2, Samuel Brem2, Jonas D. Ziegler1, Roberto Rosati2, Takashi Taniguchi3, Kenji Watanabe3, Mikhail M. Glazov4, Ermin Malic2, and Alexey Chernikov1 — 1Department of Physics, University of Regensburg, Regensburg, Germany — 2Department of Physics, Chalmers University of Technology, Gothenburg, Sweden — 3National Institute for Materials Science, Tsukuba, Ibaraki, Japan — 4Ioffe Institute, St. Petersburg, Russia
Excitons are known to dominate optical properties of semiconducting transition metal dichalcogenides (TMDCs) both for monolayers and heterostructures. While excitons can also propagate across large distances due to the two-dimensional nature of the system, their behavior remains highly sensitive to local environmental inhomogeneities. In our work, we take advantage of material encapsulation in high-quality hexagonal boron nitride to study inherent exciton propagation unobscured by disorder. Using spatially- and time-resolved photoluminescence microscopy we find highly efficient linear diffusion and pronounced non-linear phenomena. In order to explain our findings we employ a combination of numerical and analytical approaches, discuss the role of dark states as well as non-radiative exciton-exciton scattering and present a mechanism for rapid diffusion facilitated by free electron-hole plasma.