Multilayer graphene/amorphous carbon hybrid films prepared by microwave surface-wave plasma CVD: Synthesis and characterization

Hybrid films of multilayer graphene (MG) containing amorphous carbon (a-C) were synthesized on Al substrates by microwave surface-wave plasma chemical vapor deposition. Raman scattering and surface transmission electron microscopy showed that the carbon films contained a large quantity of MG when a radio frequency (RF) substrate bias was not applied. Amorphization of graphene in the carbon film was promoted by applying an RF bias, which generated Ar⁺ in the plasma. The bandgaps of the films were found to increase as the Raman intensity ratios between the 2D-band (at 2700cm^-1) and D-band (at 1350cm^-1) decreased, indicating the formation of a-C. The MG/a-C all-sp² phase of carbon hybrid films exhibited an increase in current density under 5mW/cm² of AM1.5G solar simulated irradiation as the RF bias increased because of Ar⁺-induced amorphization of the graphene.