Highly Strain-Tunable Interlayer Excitons in MoS₂/WSe₂ Heterobilayers

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Interlayer excitons in transition-metal dichalcogenide (TMDC) heterobilayers exhibit unique properties like permanent dipoles and long lifetimes.
• The influence of mechanical strain on these interlayer excitons remains largely unexplored.

Purpose of the Study:

• To experimentally investigate the effects of mechanical strain on the optoelectronic properties of interlayer excitons.
• To quantify the strain tunability of interlayer excitons in MoS2/WSe2 heterobilayers.

Main Methods:

• Fabrication of wrinkled MoS2/WSe2 heterobilayers.
• Experimental demonstration of strain tuning of Γ-K interlayer excitons using photoluminescence spectroscopy.
• Calculation of the deformation potential constant.

Main Results:

• Achieved a deformation potential constant of ~107 meV/% uniaxial strain for interlayer excitons, approximately double that of intralayer excitons.
• Observed a nonmonotonic dependence of photoluminescence intensity on strain, linked to band hybridization.
• Demonstrated higher strain tunability in heterobilayers compared to monolayers.

Conclusions:

• Mechanical strain offers a powerful tool for tuning the optoelectronic properties of interlayer excitons in TMDC heterobilayers.
• Strain engineering provides new avenues for controlling and enhancing the performance of excitonic devices.