Contactless Modulation of Intralayer and Interlayer Excitons in MoS2/WSe2 heterostructures with Acoustoelectric Fields

TL;DR

This paper demonstrates a contactless platform using surface acoustic waves to dynamically modulate intralayer and interlayer excitons in MoS2/WSe2 heterostructures, enabling advanced optoelectronic and quantum device functionalities.

Contribution

It introduces a novel, fully contactless method to control excitonic properties in 2D heterostructures using coupled piezoelectric and strain fields of SAWs.

Findings

Identified two distinct interlayer excitons with twist-angle-independent energy splitting.

Achieved tunable modulation of photoluminescence via type-II band alignment.

Demonstrated selective manipulation of excitons inducing Stark effects.

Abstract

This work presents a platform that enables surface acoustic wave (SAW) modulation of both intralayer and interlayer excitons in MoS2/WSe2 heterostructures. Harnessing the coupled piezoelectric and strain fields of SAWs, this integrated approach allows for dynamic, precise, and fully contactless control of excitonic properties, a capability essential for the realization of next generation optoelectronic, quantum photonic, and excitonic devices. We identify two distinct modulable interlayer excitons in optical communication bands: IX$_{K\Gamma}$ in the O band (around 1300 nm) and IX$_{K\!-\!K}$ in the S band (around 1500 nm); these two excitons display a robust twist-angle-independent energy splitting of 120 meV, in agreement with density functional theory (DFT) calculations. The type-II band alignment induced by the SAW not only promotes efficient exciton dissociation but also enables direct and tunable modulation of photoluminescence via the formation of confined piezoelectric potential wells. Furthermore, by simultaneously generating in-plane and out-of-plane SAW fields, the platform achieves selective manipulation of intralayer and interlayer excitons, inducing quadratic Stark effects for intralayer excitons and linear Stark effects for interlayer excitons. These findings provide new insights into SAWexciton interactions in van der Waals heterostructures, broaden the operational spectral range, and establish pathways toward on-chip acousto-optic and quantum optoelectronic devices with advanced excitonic functionality.