We report graphene films composed mostly of one or two layers of graphene grown by controlled carbon precipitation on the surface of polycrystalline Ni thin films during atmospheric chemical vapor deposition(CVD).Cont...We report graphene films composed mostly of one or two layers of graphene grown by controlled carbon precipitation on the surface of polycrystalline Ni thin films during atmospheric chemical vapor deposition(CVD).Controlling both the methane concentration during CVD and the substrate cooling rate during graphene growth can signifi cantly improve the thickness uniformity.As a result,one-or two-layer graphene regions occupy up to 87%of the fi lm area.Single layer coverage accounts for 5%11%of the overall fi lm.These regions expand across multiple grain boundaries of the underlying polycrystalline Ni fi lm.The number density of sites with multilayer graphene/graphite(>2 layers)is reduced as the cooling rate decreases.These fi lms can also be transferred to other substrates and their sizes are only limited by the sizes of the Ni fi lm and the CVD chamber.Here,we demonstrate the formation of fi lms as large as 1 in^(2).These fi ndings represent an important step towards the fabrication of large-scale high-quality graphene samples.展开更多
基金by the Materials,Structures and Devices(MSD)Focus Center,one of the five centers of the Focus Center Research Program,a Semiconductor Research Corporation program.Support from NSF/CTS 05-06830(X.J.and M.S.D)and NSF/DMR07-04197(A.R.and M.S.D.)is also acknowledged.Raman measurements were carried out in the George R.Harrison Spectroscopy Laboratory supported by NSF-CHE 0111370 and NIH-RR02594 grants.
文摘We report graphene films composed mostly of one or two layers of graphene grown by controlled carbon precipitation on the surface of polycrystalline Ni thin films during atmospheric chemical vapor deposition(CVD).Controlling both the methane concentration during CVD and the substrate cooling rate during graphene growth can signifi cantly improve the thickness uniformity.As a result,one-or two-layer graphene regions occupy up to 87%of the fi lm area.Single layer coverage accounts for 5%11%of the overall fi lm.These regions expand across multiple grain boundaries of the underlying polycrystalline Ni fi lm.The number density of sites with multilayer graphene/graphite(>2 layers)is reduced as the cooling rate decreases.These fi lms can also be transferred to other substrates and their sizes are only limited by the sizes of the Ni fi lm and the CVD chamber.Here,we demonstrate the formation of fi lms as large as 1 in^(2).These fi ndings represent an important step towards the fabrication of large-scale high-quality graphene samples.
