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Optimized Fabrication Procedure for High-Quality Graphene-based Moiré Superlattice Devices
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Soliton superlattices in twisted hexagonal boron nitride
Nature Communications
|September 27, 2019
Summary
Researchers visualized strain in hexagonal boron nitride (hBN) moiré superlattices. They found solitons forming hexagonal networks, revealing strain distribution and its impact on hBN
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Atomic van der Waals heterostructures' properties depend on interlayer coupling.
- Moiré superlattices arise from rotational misalignment or lattice mismatch, causing periodic stacking modulation.
- Lattice relaxation in large superlattice periods concentrates strain at solitons.
Purpose of the Study:
- To visualize long-range periodic superstructures in hexagonal boron nitride (hBN) crystals.
- To analyze the strain distribution and its effect on hBN's infrared-active phonons.
Main Methods:
- Atomic-force microscopy (AFM) for topography.
- Nano-infrared spectroscopy for infrared contrast analysis.
- Visualization of sub-surface hexagonal networks formed by solitons.
Main Results:
- Successfully visualized moiré superlattices in thin hBN crystals.
- Identified solitons forming sub-surface hexagonal networks with periods of hundreds of nanometers.
- Obtained spatial distribution of local strain and its correlation with infrared phonon behavior.
Conclusions:
- Solitons in hBN moiré superlattices are key to understanding strain localization.
- AFM and nano-IR spectroscopy are effective tools for probing strain in 2D materials.
- Strain significantly influences the optoelectronic properties of van der Waals heterostructures.
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