Nano-optical Visualization of Interlayer Interactions in WSe₂/WS₂ Heterostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Exciton-phonon interactions are crucial for the optical and electronic properties of transition metal dichalcogenides (TMDs).
• Existing characterization methods for excitons and phonons in TMDs lack nanoscale resolution for ultralow-frequency and interlayer modes.

Purpose of the Study:

• To develop and apply a novel nanoscale technique for direct probing of ultralow-frequency and interlayer phonons in TMD heterostructures.
• To investigate phonon behavior in nanobubbles within WSe2/WS2 heterobilayers.

Main Methods:

• Development of ultralow-frequency tip-enhanced Raman spectroscopy (UFL-TERS).
• Application of UFL-TERS for spectrally and spatially resolved nanoimaging of WSe2/WS2 heterostructures.
• Correlation analysis of spectral images to study exciton-phonon interplay.

Main Results:

• Demonstrated direct probing of interlayer (de)coupling using a novel structurally sensitive nano-optical probe.
• Analyzed phonons within nanobubbles in WSe2/WS2 heterobilayers.
• Revealed the interplay between excitons and interlayer/intralayer phonons through nanoscale spectral imaging.

Conclusions:

• The developed UFL-TERS technique provides unprecedented nanoscale insight into phonon dynamics in TMDs.
• This method allows direct characterization of interlayer coupling and exciton-phonon interactions at the nanoscale.
• The findings are crucial for understanding and engineering optoelectronic properties of 2D materials.