CF4/H2 Plasma Cleaning of Graphene Regenerates Electronic Properties of the Pristine Material

The impact on the electronic and structural properties of chemical vapor deposition (CVD) graphene transferred onto SiO2/silicon (Si) of continuous H2-based plasmas, used to remove sticky residues composed of poly(methyl methacrylate) (PMMA) and Si-based nanoparticles at the surface, was investigated. By combining X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), we found that H2 plasma treatment, which allows the simultaneous etching of Si-based nanoparticles and PMMA, causes fragmentation of a CVD graphene layer into nanoplatelets and subsequent etching of the uncovered SiO2/Si surface. We added CF4 to the H2 plasma to allow the selective etching of Si-based impurities while maintaining the quality and stability of the CVD graphene. The increase in the sp2/sp3 ratio and decrease in the Si–C bonds, evaluated from XPS analysis, reveal the removal of all residual contamination. AFM analysis confirms the efficient and selective etching of residues from the surface of graphene, which ...