Controlled synthesis of bilayer graphene on nickel

We report a uniform and low-defect synthesis of bilayer graphene on evaporated polycrystalline nickel films. We used atmospheric pressure chemical vapor deposition with ultra-fast substrate cooling after exposure to methane at 1,000A degrees C. The optimized process parameters, i.e., growth time, annealing profile and flow rates of various gases, are reported. By using Raman spectroscopy mapping, the ratio of 2D to G peak intensities (I (2D)/I (G)) is in the range of 0.9 to 1.6 over 96% of the 200 mu m x 200 mu m area. Moreover, the average ratio of D to G peak intensities (I (D)/I (G)) is about 0.1.