Hyperspectral imaging of structure and composition in atomically thin heterostructures.

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Two-dimensional (2D) materials like graphene and hexagonal boron nitride (h-BN) form complex heterostructures with diverse functionalities.
• Characterizing these ultrathin heterostructures, including lateral junctions and twisted bilayers, presents significant challenges.

Purpose of the Study:

• To develop and demonstrate a DUV-vis-NIR hyperspectral microscope for comprehensive characterization of 2D material heterostructures.
• To establish quantitative structure-property relationships in graphene/h-BN lateral heterojunctions and twisted bilayer graphene (tBLG).

Main Methods:

• Utilized a DUV-vis-NIR hyperspectral microscope for all-optical mapping of chemical composition and interlayer rotations.
• Employed transmission electron microscopy (TEM) for complementary structural analysis.
• Investigated samples on both transparent and nontransparent silicon/SiO2 substrates.

Main Results:

• Achieved comprehensive, all-optical mapping of chemical composition in graphene/h-BN lateral heterojunctions.
• Quantified interlayer rotations in twisted bilayer graphene (tBLG) via hyperspectral imaging.
• Confirmed abrupt interfaces in graphene/h-BN heterojunctions and a direct correlation between twist angle and optical resonances in tBLG.
• Demonstrated facile fabrication of atomically thin heterostructure devices on silicon/SiO2 substrates with known composition and structure.

Conclusions:

• The DUV-vis-NIR hyperspectral microscope is a powerful tool for characterizing complex 2D material heterostructures.
• This technique facilitates the understanding and fabrication of advanced heterostructure devices with tailored properties.
• Enabled precise characterization of interfaces and twist angles, crucial for device performance.