Selective Formation of Zigzag Edges in Graphene Cracks

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Graphene, a single layer of carbon atoms, possesses unique electronic properties.
• Chemical vapor deposition (CVD) is a common method for growing large-area graphene.
• Controlling edge structure in graphene is crucial for its electronic applications.

Purpose of the Study:

• To investigate the unconventional cracking of graphene during cooling after CVD.
• To characterize the crystallographic nature and quality of the generated graphene edges.
• To explore the potential of these crack-derived features for electronic device applications.

Main Methods:

• Observation of graphene films post-CVD cooling on copper (Cu) foil.
• Raman spectroscopy for edge characterization.
• Electrical transport measurements to demonstrate carrier tuning.
• Finite element analysis (FEA) for thermal stress modeling.

Main Results:

• Thermally induced, crystallography-selective cracking of graphene was observed.
• Crack-derived edges exhibit smoother zigzag structures compared to CVD grain boundaries.
• Graphene nanogaps formed by cracks allowed for effective carrier tuning via electric field effect.
• Cracking is attributed to uniaxial tension from Cu substrate cooling and stress concentration.

Conclusions:

• Unconventional thermal cracking offers a novel route to generate high-quality zigzag graphene edges.
• The observed cracking mechanism provides insights into graphene-substrate interactions during cooling.
• Crack-induced nanogaps are promising for fabricating graphene-based electronic devices with tunable properties.