posted on 2024-03-12, 21:12authored bySteffi Y. Woo, Fuhui Shao, Ashish Arora, Robert Schneider, Nianjheng Wu, Andrew J. Mayne, Ching-Hwa Ho, Mauro Och, Cecilia Mattevi, Antoine Reserbat-Plantey, Álvaro Moreno, Hanan Herzig Sheinfux, Kenji Watanabe, Takashi Taniguchi, Steffen Michaelis de Vasconcellos, Frank H. L. Koppens, Zhichuan Niu, Odile Stéphan, Mathieu Kociak, F. Javier García de Abajo, Rudolf Bratschitsch, Andrea Konečná, Luiz H. G. Tizei
Control over the optical properties of atomically thin
two-dimensional
(2D) layers, including those of transition metal dichalcogenides (TMDs),
is needed for future optoelectronic applications. Here, the near-field
coupling between TMDs and graphene/graphite is used to engineer the
exciton line shape and charge state. Fano-like asymmetric spectral
features are produced in WS2, MoSe2, and WSe2 van der Waals heterostructures combined with graphene, graphite,
or jointly with hexagonal boron nitride (h-BN) as
supporting or encapsulating layers. Furthermore, trion emission is
suppressed in h-BN encapsulated WSe2/graphene
with a neutral exciton red shift (44 meV) and binding energy reduction
(30 meV). The response of these systems to electron beam and light
probes is well-described in terms of 2D optical conductivities of
the involved materials. Beyond fundamental insights into the interaction
of TMD excitons with structured environments, this study opens an
unexplored avenue toward shaping the spectral profile of narrow optical
modes for application in nanophotonic devices.