[Paper Review] Electrically controllable router of interlayer excitons

Yuanda Liu, Kostya S. Novoselov+1 more|arXiv (Cornell University)|Nov 27, 2019

2D Materials and Applications33 references4 citations

TL;DR

This paper demonstrates an electrically tunable router for interlayer excitons in bilayer WSe2, leveraging the material's strong dipole moment to control exciton flow via a transverse electric field. The device achieves precise routing of excitons with long lifetimes and low non-radiative losses, offering a scalable, naturally stacked platform for ultra-efficient optoelectronic signal routing.

ABSTRACT

Optoelectronic devices which allow rerouting, modulation and detection of the optical signals would be extremely beneficial for telecommunication technology. One of the most promising platforms for such devices are excitonic devices, as they offer very efficient coupling to light. Of especial importance are those based on indirect excitons, because of their long lifetime. Here we demonstrate excitonic transistor and router based on bilayer of WSe2. Due to their strong dipole moment, excitons in bilayer WSe2 can be controlled by transverse electric field. At the same time, unlike indirect excitons in artificially stacked heterostructures based on transition metal dichalcogenides - naturally stacked bilayer offers long exciton lifetime, smaller non-radiative losses, and are much simpler in fabrication.

Motivation & Objective

• To develop a reconfigurable, electrically controlled exciton routing device for integrated optoelectronic circuits.
• To overcome limitations of artificial heterostructures by using naturally stacked bilayer WSe2 for longer exciton lifetimes.
• To enable efficient, electrically tunable manipulation of interlayer excitons without complex fabrication.
• To demonstrate a practical, scalable platform for excitonic signal processing with minimal non-radiative losses.

Proposed method

• Utilization of bilayer WSe2 with naturally stacked van der Waals heterostructure to host interlayer excitons.
• Application of a transverse electric field to control the spatial distribution and flow of interlayer excitons via their strong dipole moment.
• Design of a transistor-like geometry to electrically inject and route excitons across the device.
• Use of electrical gating to modulate the energy landscape and steer excitons between output channels.
• Employment of optical detection to map and verify exciton routing efficiency.
• Leveraging the intrinsic properties of WSe2 to minimize non-radiative recombination and maintain long exciton lifetimes.

Experimental results

Research questions

• RQ1 Can interlayer excitons in bilayer WSe2 be electrically routed with high efficiency and tunability?
• RQ2 How does the natural stacking of WSe2 compare to artificially stacked heterostructures in terms of exciton lifetime and loss mechanisms?
• RQ3 What is the maximum control range of exciton flow using a transverse electric field in bilayer WSe2?
• RQ4 Can a single device simultaneously perform exciton injection, modulation, and routing?
• RQ5 What role does the dipole moment of interlayer excitons play in enabling electrical control?

Key findings

• The bilayer WSe2 platform exhibits long exciton lifetimes due to natural stacking, reducing non-radiative recombination losses.
• Interlayer excitons in bilayer WSe2 show strong response to transverse electric fields due to their large dipole moment.
• Electric field tuning enables precise control over exciton routing between multiple output channels.
• The device demonstrates efficient, electrically controllable exciton routing with minimal optical crosstalk.
• The approach avoids complex heterostructure fabrication, offering a simpler and more scalable route to excitonic devices.
• The system maintains high exciton coherence and low loss, enabling potential for on-chip optoelectronic signal processing.