Adlayer-Free Large-Area Single Crystal Graphene Grown on a Cu(111) Foil.

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Chemical vapor deposition (CVD) has yielded "single layer" graphene, but large areas often contain undesirable adlayers.
• Subsurface carbon in copper (Cu) foils is identified as the cause of adlayer formation during graphene growth.

Purpose of the Study:

• To develop a method for growing truly large-area, adlayer-free single layer graphene.
• To investigate the role of subsurface carbon in adlayer formation.
• To demonstrate the potential of the resulting graphene for electronic applications.

Main Methods:

• Copper foils were annealed in a hydrogen atmosphere to deplete subsurface carbon.
• Single layer graphene was grown on treated Cu(111) and polycrystalline Cu foils using CVD.
• Characterization of graphene films and their adlayer content was performed.
• Fabrication of field-effect transistors (FETs) on the synthesized graphene.

Main Results:

• Annealing in hydrogen effectively removed subsurface carbon from Cu foils.
• Adlayer-free single crystal graphene on Cu(111) exhibited parallel, centimeter-long folds.
• Adlayer-free polycrystalline graphene on Cu foils showed quasi-randomly distributed folds and wrinkles.
• High-performance FETs were successfully fabricated on the adlayer-free single crystal graphene.

Conclusions:

• Subsurface carbon depletion is crucial for achieving large-area, adlayer-free single layer graphene via CVD.
• The developed method yields high-quality graphene suitable for advanced electronic devices.
• This work overcomes a significant limitation in large-scale graphene production.