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DS: Fachverband Dünne Schichten

DS 20: 2D materials: Chalcogenides I (joint session HL/DS)

DS 20.13: Vortrag

Mittwoch, 14. März 2018, 12:45–13:00, A 151

Highly polarized excitons in atomically thin and bulklike 1T^′-ReSe₂ — •A. Arora¹, J. Noky², M. Drüppel², B. Jariwala³, T. Deilmann⁴, R. Schneider¹, R. Schmidt¹, O. Del Pozo-Zamudio¹, T. Stiehm¹, A. Bhattacharya³, P. Krüger², S. Michaelis de Vasconcellos¹, M. Rohlfing², and R. Bratschitsch¹ — ¹Institute of Physics, University of Münster, Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany — ²Institute of Solid State Theory, University of Münster, D-48149 Münster, Germany — ³Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India — ⁴Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark

Using low-temperature polarized optical absorption and photoluminescence spectroscopy, supported by GW-BSE ab initio calculations, we investigate excitons in the van der Waals semiconductor 1T^′-ReSe₂ [1]. A red shift of the excitonic transition energy is observed when the crystal thickness is reduced from bulk towards a monolayer. The excitons exhibit a strong polarization anisotropy within the plane of the crystal, with dipole vectors pointing towards different crystal directions. This polarization behavior persists from bulk to monolayer thickness. We find that the excitons are strongly confined within the individual crystal layers, even for the bulklike case. We find a direct band gap in 1T^′-ReSe₂ in our calculations, regardless of the crystal thickness. Our results pave the way for polarization-sensitive applications using two-dimensional semiconductors. [1] A. Arora et al., Nano Lett. 17, 3202-3207 (2017).