Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 8: 2D Materials Beyond Graphene I

O 8.2: Vortrag

Montag, 20. März 2017, 10:45–11:00, REC/PHY C213

Photocarrier dynamics and interaction effects of interlayer excitons in WSe₂/MoSe₂ heterostructures — •Philipp Nagler, Gerd Plechinger, Alexey Chernikov, Christian Schüller, and Tobias Korn — Institut für Experimentelle und Angewandte Physik, Regensburg, Germany

Atomically thin transition metal dichalcogenides (TMDCs) such as WSe₂ or MoSe₂ have lately emerged as a promising platform to study the physics of excitons in strongly confined systems. Thereby, the use of transfer techniques allows for the fabrication of van der Waals heterostructures by deterministic stacking of individual monolayers. It is expected that type-II band alignment of the individual monolayers results in the formation of spatially indirect excitons. Here, we present a detailed study of the optical properties of interlayer excitons in a WSe₂/MoSe₂ heterostructure using static and time-resolved photoluminescence measurements. At low temperatures, we observe the emergence of an energetically separated (1.4 eV) and spectrally sharp (FWHM < 20meV) feature, which we attribute to the emission of interlayer excitons. Power-dependent measurements show a considerable blue shift of the interlayer exciton peak position due to dipolar exciton-exciton interaction effects. Finally, we employ a streak camera system in order to reveal the photocarrier dynamics of interlayer excitons for varying temperatures. The lifetime at low temperatures amounts to several nanoseconds, which is a consequence of the reduced oscillator strength of the interlayer exciton.