Non-Linear Optics at Twist Interfaces in h-BN/SiC Heterostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Twistronics, the study of electronic properties in twisted 2D materials, faces challenges in precise control and single-crystalline requirements.
• Existing methods for creating twisted interfaces are complex and difficult to scale for practical applications.

Purpose of the Study:

• To introduce a simple, scalable method for achieving twisted-interface-dependent properties in 2D materials.
• To explore structure-property correlations in nanocrystalline hexagonal boron nitride (h-BN) films grown on 3D substrates.

Main Methods:

• Directly growing nanocrystalline h-BN thin films on silicon carbide (4H-SiC) substrates with high lattice mismatch.
• Utilizing first-principles calculations based on time-dependent density functional theory.

Main Results:

• Nanocrystalline h-BN films exhibited strong non-linear second-harmonic generation and ultra-low cross-plane thermal conductivity at room temperature.
• Twisted domain edges between van der Waals stacked nanocrystals with random in-plane orientations were identified as the cause of these properties.
• Calculations confirmed strong even-order optical nonlinearity in twisted h-BN layers.

Conclusions:

• Directly deposited 2D nanocrystalline films on 3D substrates offer an accessible route to engineered twist-interfaces.
• This method provides a simple and scalable approach for integrating 2D twistronics into 3D devices for advanced nanotechnology.