Accurate Layer-Number Determination of Hexagonal Boron Nitride Using Optical Characterization

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Accurate layer number determination is critical for hexagonal boron nitride (hBN) in advanced applications.
• Integration of hBN with other 2D materials requires precise layer counting for controlled device properties.

Purpose of the Study:

• To develop and present a nondestructive method for accurate hexagonal boron nitride (hBN) layer number (N) determination.
• To enhance the efficiency of identifying monolayer and few-layer hBN for research and device fabrication.

Main Methods:

• Combining optical contrast analysis with second harmonic generation (SHG) measurements.
• Utilizing red-filtered optical images for initial layer contrast assessment on SiO2/Si substrates.
• Employing SHG to distinguish between even and odd hBN layers, reducing uncertainty.
• Implementing a real-time detection technique for rapid monolayer and few-layer hBN identification.

Main Results:

• The combined optical and SHG method achieves precise hBN layer number determination with reduced uncertainty.
• Red-filtered optical imaging provides a clear contrast step for layer counting (±1 layer).
• SHG successfully differentiates even and odd hBN layers, improving accuracy.
• Real-time detection significantly enhances the efficiency of identifying monolayer and few-layer hBN.

Conclusions:

• This nondestructive, combined optical and SHG approach offers a practical and accurate method for hBN layer number determination.
• The developed techniques are valuable for studies involving twisted hBN interfaces and van der Waals heterostructures.
• Improved flake identification efficiency facilitates future research and integration of hBN in novel electronic and photonic devices.