Competitive growth between the top and bottom layers of few-layer graphene at the domain boundary merging stage

Compared with monolayer graphene, few-layer graphene (FLG) also has a broader application prospect in the fields of composite materials, conductive coatings, metal corrosion prevention and electronic devices requiring tunable electronic structures. Herein, FLG is grown on Cu foil by chemical vapor deposition (CVD) and the merging of graphene domain boundary (GDB) network is directly observed by optical microscope (OM). Raman spectra and energy dispersive spectroscopy (EDS) results show that the defect degree of graphene at GDBs is lower than that at domain interior. Raman mapping results indicate that the structure of FLG grown at 980 degrees C is inhomogeneous and there exist a terraced structure at the GDBs. The atomic force microscopy (AFM) results show that the FLG grown at 980 degrees C has about -7 layers at the GDBs and -13 layers at domain interior, respectively. In addition, the Raman spectra results also disclose an unusual phenomenon that graphene at GDBs grown at 980 degrees C has lower ID/IG ratios than that grown at 1000 degrees C. A competitive growth mechanism of the top and bottom layers of FLG is proposed to shed light on the synergistic effect of catalysis of Cu and temperature on the late growth stage of FLG.