Fabrication of vertical van der Waals gap array using single-and multi-layer graphene.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Vertically aligned graphene layers are crucial for advanced electronic and optical devices.
• Understanding the properties of graphene in metal-graphene-metal structures is essential for device optimization.

Purpose of the Study:

• To develop a manufacturing method for graphene van der Waals gaps.
• To investigate the optical properties of graphene in THz frequencies within these structures.

Main Methods:

• Graphene synthesis on copper (Cu) films using plasma-enhanced chemical vapor deposition (PECVD).
• Fabrication of Cu-graphene-Cu laminated structures.
• Characterization using resonant Raman spectroscopy, transmission electron microscopy, and terahertz-time domain spectroscopy (THz-TDS).

Main Results:

• Optimized PECVD synthesis of graphene on Cu films.
• Demonstrated constant THz amplitude transmission through graphene van der Waals gaps, irrespective of gap width.
• Established a linear relationship between graphene's out-of-plane optical dielectric constant and gap width at THz frequencies.

Conclusions:

• A novel manufacturing method for graphene van der Waals gaps was successfully developed.
• The optical dielectric constant of graphene at THz frequencies is directly proportional to the gap width.
• The methodology can be extended to study other 2D materials and applied to metal-graphene-metal devices.