Scanning tunnelling microscopy of suspended graphene

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Graphene, a single layer of carbon atoms, exhibits unique electronic and mechanical properties.
• Studying suspended graphene is crucial for understanding its intrinsic characteristics, free from substrate interactions.
• Previous studies often involved graphene supported on substrates, potentially influencing observed phenomena.

Purpose of the Study:

• To investigate suspended graphene using scanning tunneling microscopy (STM) at atomic resolution.
• To characterize the surface morphology and identify any structural features present in suspended mono- and bi-layer graphene.
• To establish a method for preparing clean suspended graphene surfaces for atomic-scale analysis.

Main Methods:

• High-temperature annealing of suspended graphene samples to remove surface contaminants.
• Utilizing scanning tunneling microscopy (STM) to achieve atomic resolution imaging.
• Analysis of mono-layer and bi-layer suspended graphene structures.

Main Results:

• Achieved atomic resolution imaging of suspended graphene for the first time.
• Successfully removed surface contamination through high-temperature annealing.
• Observed static local corrugations, or ripples, on both mono-layer and bi-layer suspended graphene.

Conclusions:

• High-temperature annealing is an effective method for preparing clean suspended graphene surfaces for STM analysis.
• Suspended graphene, even in its clean state, exhibits intrinsic structural features like ripples.
• This study provides a foundation for further investigations into the properties of freestanding graphene.