Optical reflectance measurement of large-scale graphene layers synthesized on nickel thin film by carbon segregation

The change of surface roughness during graphene synthesis on evaporated Ni thin films was monitored. It was found that Ni is highly agglomerated during high temperature annealing but the surface roughness is made smoother by the coverage of graphene. It is demonstrated that diffuse reflectance is a fast and convenient technique for evaluating surface roughness over a large area of graphene on a metal film, and specular reflectance is a good indicator of the coverage of graphene on the metal film.