Engineering 2D material exciton lineshape with graphene/h-BN encapsulation

Abstract

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. Remarkable advances have been achieved through alloying, chemical and electrical doping, and applied strain. However, the integration of TMDs with other 2D materials in van der Waals heterostructures (vdWHs) to tailor novel functionalities remains largely unexplored. Here, the near-field coupling between TMDs and graphene/graphite is used to engineer the exciton lineshape and charge state. Fano-like asymmetric spectral features are produced in WS${}_2$, MoSe${}_2$ and WSe${}_2$ vdWHs 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 WSe${}_2$/graphene with a neutral exciton redshift (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.

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Cited by in corpus (4)

• Nano-optics of transition metal dichalcogenides and their van der Waals heterostructures with electron spectroscopies
• Electrically Controlled Interfacial Charge Transfer Induced Excitons in MoSe2-WSe2 Lateral Heterostructure
• Photonics in Flatland: Challenges and Opportunities for Nanophotonics with 2D Semiconductors
• Excitons in epitaxially grown WS2 on Graphene: a nanometer-resolved EELS and DFT study