Optical reflectance imaging reveals interlayer coupling in mechanically stacked MoS₂ and WS₂ bilayers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Optical reflectance imaging is widely used for 2D material characterization due to its speed and simplicity.
• Its application in studying interlayer phenomena in stacked 2D materials has been limited.

Purpose of the Study:

• To demonstrate optical imaging's capability in revealing interlayer coupling in stacked 2D materials.
• To establish a method for characterizing interlayer coupling in MoS2 and WS2 bilayers.

Main Methods:

• Utilizing optical reflectance contrast against a substrate to probe interlayer coupling.
• Co-optimizing illumination wavelength and SiO2 film thickness for accurate measurements.
• Employing multilayer optical calculations and interlayer gap analysis.

Main Results:

• Optical imaging successfully revealed the nature of interlayer coupling in stacked MoS2 and WS2 bilayers.
• The study identified optimal conditions (wavelength and SiO2 thickness) for determining interlayer coupling.
• Multilayer optical calculations validated the experimental observations.

Conclusions:

• Optical reflectance imaging can be effectively used to study interlayer phenomena in stacked 2D materials.
• This technique offers a rapid method for characterizing constructed 2D material systems.
• The findings pave the way for advanced analysis of van der Waals heterostructures.