Sub-10 nm Visualization of Trions in Ultralow-Strained Monolayer MoSe₂

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Understanding nanoscale excitonic quasiparticles in low-dimensional semiconductors is crucial for advanced nanoexcitonic devices and integrated circuits.
• Direct nanoscale visualization of trions under ultralow strain is challenging due to weak emission and limited far-field technique resolution.

Purpose of the Study:

• To present a novel hybrid plasmonic-SNOM (p-SNOM) system for enhanced nanoscale visualization of excitons and trions.
• To investigate exciton and trion distributions in monolayer MoSe2 on gold nanostars under ultralow strain.
• To enable efficient exciton-to-trion conversion and high-resolution trion visualization in 2D materials.

Main Methods:

• Development of a hybrid structure integrating a plasmonic-SNOM (p-SNOM) system.
• Utilized hyperspectral tip-enhanced photoluminescence (TEPL) nanoimaging with sub-10 nm resolution.
• Investigated monolayer MoSe2 on gold nanostar (AuNS) particles.

Main Results:

• Achieved up to 190% enhancement in integrated photoluminescence (PL) intensity.
• Observed a trion population reaching 20% at an ultralow strain threshold of 0.05%.
• Demonstrated the capability for efficient exciton-to-trion conversion and high-resolution trion visualization.

Conclusions:

• The developed p-SNOM platform enables unprecedented visualization of trions in 2D materials under ultralow strain.
• This approach facilitates efficient exciton-to-trion conversion, critical for next-generation optoelectronic devices.
• The study provides a powerful tool for probing nanoscale excitonic behavior in transition metal dichalcogenides (TMDs).