Efficient Interlayer Relaxation and Transition of Excitons in Epitaxial and Non-epitaxial MoS2/WS2 Heterostructures

Abstract

Semiconductor heterostructures provide a powerful platform for the engineering of excitons. Here we report the excitonic properties of two-dimensional (2D) heterostructures that consist of monolayer MoS2 and WS2 stacked epitaxially or non-epitaxially in the vertical direction. We find similarly efficient interlayer relaxation and transition of excitons in both the epitaxial and nonepitaxial heterostructures. This is manifested by a two orders of magnitude decrease in the photoluminescence and the appearance of an extra absorption peak at low energy region. The MoS2/WS2 heterostructures show weak interlayer coupling and can essentially act as atomicscale heterojunctions with the intrinsic bandstructures of the two monolayers largely preserved. They are particularly promising for the applications that request efficient dissociation of excitons and strong light absorption, including photovoltaics, solar fuels, photodetectors, and optical modulators. Our results also indicate that 2D heterostructures promise unprecedented capabilities to engineer excitons from the atomic level without concerns of interfacial imperfection.

References in corpus (6)

• Synthesis of Large-Area MoS2 Atomic Layers with Chemical Vapor Deposition
• Atomically thin p-n junctions with van der Waals heterointerfaces
• Ultrafast Charge Transfer in Atomically Thin MoS2/WS2 Heterostructures
• Vertical Field Effect Transistor based on Graphene-WS2 Heterostructures for flexible and transparent electronics
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• Giant Valley-Zeeman Splitting from Spin-Singlet and Spin-Triplet Interlayer Excitons in WSe2/MoSe2 Heterostructure
• Electronic and optical excitations of two-dimensional ZrS${}_2$ and HfS${}_2$ and their heterostructure
• Enhanced trion emission in monolayer MoSe2 by constructing a type-I van der Waals heterostructure
• Electric Field Tuning of Band Offsets in Transition Metal Dichalcogenides
• Room temperature infrared photodetectors with hybrid structure based on 2D materials
• Fast Fabrication of WS2/Bi2Se3 Heterostructures for High Performance Photodetection
• Optical properties of monolayer, multilayer, and bulk BiI${}_3$ studied using time-dependent density functional theory
• Exciton Mott Transition in Two-Dimensional Semiconductors
• Moiré exciton dynamics and moiré exciton-phonon interaction in a WSe${}_2$/MoSe${}_2$ heterobilayer