Mesoscale Epitaxy in Two-Dimensional Anisotropic ReS₂/MoS₂ Vertical Heterostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Epitaxy in 2D vertical heterostructures is well-studied, but the impact of in-plane anisotropy remains largely unknown.
• Understanding anisotropy is crucial for designing novel 2D heterostructures with tailored electronic and optical properties.

Purpose of the Study:

• To investigate the effects of in-plane anisotropy on epitaxy in 2D vertical heterostructures.
• To synthesize and characterize ReS2/MoS2 vertical heterostructures, combining anisotropic ReS2 and isotropic MoS2.
• To elucidate the complex interplay between interfacial epitaxy, lattice mismatch strain, and anisotropy.

Main Methods:

• Chemical vapor deposition (CVD) for synthesizing ReS2/MoS2 vertical heterostructures.
• Scanning/transmission electron microscopy (S/TEM) for detailed microstructural analysis.
• Density functional theory (DFT) calculations to model interfacial phenomena and strain relaxation.

Main Results:

• Observed differing abilities to relax interlayer registry along crystallographic directions due to lattice mismatch.
• Identified a novel phenomenon termed "mesoscale epitaxy" where variations in Re chain direction create stripe domains.
• Demonstrated an overall effective lattice registry on longer length scales through a quilt-like pattern.

Conclusions:

• In-plane anisotropy significantly influences epitaxy in 2D vertical heterostructures.
• Mesoscale epitaxy is a key mechanism for managing lattice mismatch and achieving registry in anisotropic heterostructures.
• This work provides fundamental insights into the growth mechanisms of complex 2D materials.