Charged nano-domes and bubbles in epitaxial graphene

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Epitaxial graphene grown on silicon carbide (SiC) is a promising material for electronic applications.
• Understanding the morphology and electronic properties of graphene nanostructures is crucial for device fabrication.

Purpose of the Study:

• To report the first observation of charged graphene nano-structures (bubbles and domes).
• To investigate the influence of these nanostructures on graphene's electronic, mechanical, and optical properties.

Main Methods:

• Atomic Force Microscopy (AFM) for surface topography.
• Ultrasonic Force Microscopy (UFM) for nanomechanical properties (stiffness).
• Raman Spectroscopy for material composition and electronic properties.

Main Results:

• Identified graphene bubbles and domes (150–200 nm to a few μm) with heights of 5–12 nm, indicating freestanding layers.
• Confirmed graphene composition and revealed defect variations and carrier density distribution.
• Observed charge redistribution at the bubble–substrate interface, forming a charged capacitance and potentially opening a 5 meV minigap.

Conclusions:

• The novel graphene nano-structures exhibit unique morphological and electronic characteristics.
• The charged bubble–substrate interface is a key feature influencing graphene's properties.
• These findings offer insights into controlling epitaxial graphene for advanced electronic applications.