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HL: Fachverband Halbleiterphysik
HL 74: Poster IIIA
HL 74.3: Poster
Donnerstag, 19. März 2020, 15:00–17:30, P2/2OG
Direct Measurement of the Radiative Pattern of Exciton Complexes in a Tungsten Diselenide Monolayer — •Lorenz Maximilian Schneider1, Shanece S. Esdaille2, Daniel A. Rhodes2, Katayun Barmak3, James C. Hone2, and Arash Rahimi-Iman1 — 1Faculty of Physics and Materials Sciences Center, Philipps-Universität Marburg, Marburg, 35032, Germany — 2Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA — 3Department of Applied Physics and Applied Math, Columbia University, New York, NY 10027, USA
Due to the extraordinary high Coulomb interaction found in monolayers of transition-metal dichalcogenides, not only the binding energies of higher-order excitonic complexes are in the tens of meV's but also their fine structure is considerable, arising from the short- and long-range part of the Coulomb exchange integral. Such strong electronic interaction also leads to the hybridization of dark excitonic states into one dipole-allowed for z-polarization but spin-forbidden exciton branch, referred to as "grey" exciton, and another one that is both spin and dipole forbidden. While there have been some indirect measurement reports revealing the presence of the grey z-polarized exciton mode, no direct measurement of the radiation pattern has been performed. Here, we present an investigation of a high-quality h-BN encapsulated monolayer, where angle resolved spectroscopy has been used to directly reveal and extract the radiation pattern of bright and grey excitons. The in-plane and out-of-plane dipole modes can indeed be directly identified by their emission under low and high emission angles.