Thickness identification of two-dimensional materials by optical imaging.

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Two-dimensional (2D) materials such as graphene and molybdenum disulfide (MoS2) are of significant research interest.
• Understanding the thickness of these materials is crucial for characterizing their unique properties and enabling applications.

Purpose of the Study:

• To propose and validate a simple, quantitative, and universal optical imaging method for determining the thickness of various 2D materials.
• To establish a fast and cost-effective technique for thickness identification suitable for large-scale production.

Main Methods:

• Utilizing optical imaging to capture images of 2D materials on a substrate.
• Quantifying image contrast by analyzing red (R), green (G), and blue (B) values of pixels.
• Correlating contrast values with material thickness through experimental measurements and Fresnel equation calculations.

Main Results:

• Demonstrated a linear relationship between optical image contrast and the thickness of 2D materials.
• Successfully identified the thickness of mechanically exfoliated graphene, nitrogen-doped CVD graphene, graphene oxide, and MoS2.
• Validated the findings through calculations based on the Fresnel equation.

Conclusions:

• Optical imaging provides a facile, rapid, and cost-effective approach for precise thickness determination of 2D materials.
• This method supports fundamental research and facilitates the development of future applications for 2D materials.