Filtering the photoluminescence spectra of atomically thin semiconductors with graphene

Etienne Lorchat (1) , Luis E Parra López (1) , Cédric Robert (2) , Delphine Lagarde (3) , Guillaume Froehlicher (1) , Takashi Taniguchi , Kenji Watanabe , Xavier Marie (4) , Stéphane Berciaud (3)

1 IPCMS - Institut de Physique et Chimie des Matériaux de Strasbourg
2 Optoélectronique Quantique (LPCNO)
3 LPCNO - Laboratoire de physique et chimie des nano-objets
4 LPCNO - Laboratoire de physique et chimie des nano-objets

Atomically thin semiconductors made from transition metal dichalcogenides (TMDs) are model systems for investigations of strong light-matter interactions and applications in nanophotonics, opto-electronics and valley-tronics. However, the photoluminescence spectra of TMD monolayers display a large number of features that are particularly challenging to decipher. On a practical level, monochromatic TMD-based emitters would be beneficial for low-dimensional devices but this challenge is yet to be resolved. Here, we show that graphene, directly stacked onto TMD monolayers enables single and narrow-line photoluminescence arising solely from TMD neutral excitons. This filtering effect stems from complete neutralization of the TMD by graphene combined with selective non-radiative transfer of long-lived excitonic species to graphene. Our approach is applied to four tungsten and molybdenum-based TMDs and establishes TMD/graphene heterostructures as a unique set of opto-electronic building blocks, suitable for electroluminescent systems emitting visible and near-infrared photons at near THz rate with linewidths approaching the lifetime limit.

Domaines: Matière Condensée [cond-mat]

Etienne Lorchat, Luis E Parra López, Cédric Robert, Delphine Lagarde, Guillaume Froehlicher, et al.. Filtering the photoluminescence spectra of atomically thin semiconductors with graphene. Nature Nanotechnology, 2020, 15 (4), pp.283-288. ⟨10.1038/s41565-020-0644-2⟩. ⟨hal-03089577⟩