Visualising the strain distribution in suspended two-dimensional materials under local deformation

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Two-dimensional (2D) materials exhibit unique properties sensitive to mechanical strain.
• Understanding strain distribution at the nanoscale is crucial for 2D material applications.
• Current methods for strain analysis in 2D materials have limitations.

Purpose of the Study:

• To develop and demonstrate a combined atomic force microscopy (AFM) and Raman spectroscopy technique.
• To investigate strain distribution around localized deformations in suspended 2D materials.
• To enable nanoscale strain engineering of 2D materials.

Main Methods:

• Simultaneous AFM and laterally resolved Raman spectroscopy.
• Using AFM tip for nanoindentation to induce localized strain in suspended few-layer graphene.
• Hyperspectral Raman mapping to visualize strain via G and 2D band frequency shifts.

Main Results:

• Demonstrated in situ visualization of strain distribution around AFM tip-induced deformations.
• Showed that nm-sized AFM tip contact creates a 2D strain field with μm dimensions.
• Validated the strain-dependent frequency shifts of graphene's G and 2D Raman bands.

Conclusions:

• The combined AFM/Raman approach is effective for studying nanoscale strain in 2D materials.
• This technique provides a critical tool for nanoscale strain engineering.
• Enables precise control and understanding of mechanical properties in 2D materials.