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O: Fachverband Oberflächenphysik

O 113: 2D materials beyond graphene: TMDCs, silicene and relatives V

O 113.2: Talk

Friday, March 16, 2018, 10:45–11:00, MA 043

k-space indirect interlayer excitons in MoS₂/WSe₂ van der Waals heterostructures — •J. Kunstmann¹, F. Mooshammer², P. Nagler², A. Chaves^3,4, F. Stein¹, N. Paradiso², G. Plechinger², C. Strunk², C. Schüller², G. Seifert¹, D. R. Reichman⁴, and T. Korn¹ — ¹TU Dresden, DE — ²Universität Regensburg, DE — ³Universidade Federal do Ceara, BRA — ⁴Columbia University, USA

In heterobilayers of transition metal dichalcogenides (TMDCs) a new type of exciton emerges, where electron and hole are spatially separated. These interlayer excitons allow exploration of many-body quantum phenomena and are ideally suited for valleytronic applications. Mostly, a basic model of fully spatially-separated electron and hole stemming from the K valleys of the monolayer Brillouin zones is applied to describe such excitons. Here, we combine photoluminescence spectroscopy and first principle calculations to expand the concept of interlayer excitons. We identify a partially charge-separated electron-hole pair in MoS₂/WSe₂ heterostructures residing at the Γ and K valleys. We control the emission energy of this new type of k-space indirect, yet strongly-bound exciton by variation of the relative twist angle. These findings represent a crucial step towards the understanding and control of excitonic effects in TMDC heterostructures and devices.