CVD growth of continuous and spatially uniform single layer graphene across grain boundary of preferred (111) oriented copper processed by sequential melting-resolidification-recrystallization
The properties of catalyst used for CVD growth has significant influence on the quality the graphene grown. Single crystalline or preferred (111) oriented with smooth surface is most essential criterion for growth of high quality graphene on copper substrate. Herein, the effective strategy of pre-heat treatment of copper substrate for the growth of improved quality single layer graphene is demonstrated. The sequential melting, resolidification and recrystallization with controlled slow cooling rate leads to preferred (111) oriented grain growth in copper substrate and was confirmed with XRD studies. The grain growth evolution and strain relaxation, correlated with surface smoothening was inferred from AFM studies. The Raman spectroscopy measurement signifies improved quality of the CVD grown graphene which is almost free from multilayer patches that are usually associated with the routine CVD growth process. The Raman mapping carried out directly on graphene/copper surface reveals spatial continuity and uniformity of graphene quality across the copper grain boundaries over large area which signifies the importance of the surface improvement, uniform catalytic and crystallographic environment of the beneath surface. Hence, the feasible process of the high quality graphene growth was achieved with simple but effective strategy of preheat treatment involving melting resolidification and recrystallization of copper substrate.