Study On The Graphene Preparation On Cu–Ni Alloy Substrate By Chemical Vapor Deposition

Graphene is the latest member of the carbon material discovered recently. The perfect two-dimensional structure and many peculiar properties of graphene attract tremendous interest of the whole world scientists. Nowadays graphene is produced by many methods. However, most of the preparation methods are constrained by many factors, such as doping, catalysis, substrate, temperature and so on. Consequently, the application of graphene is restricted. In this paper, graphene is prepared on the Cu–Ni alloy substrate with benzene as carbon source by chemical vapor deposition. A new way of graphene preparation is developed.Three Cu–Ni alloy thin films were prepared by double targets magnetron sputtering method. Sputtering power of Ni target remained constant for 100W. Sputtering power of Cu target was 50W, 100W, 150W. The samples were characterized by energy dispersive analysis of X-rays (EDAX). The ratio of Cu and Ni was accurately determined. Meanwhile, Cu film and Ni film were prepared respectively , and measured with X-ray diffraction (XRD) for comparison.Three graphene samples were fabricated on the same kind of Cu–Ni alloy substrates at variable temperature of 800℃, 600℃and 400℃, respectively. The results show that graphene can be prepared at 400℃. We continued to lower the temperature and no graphene signal was observed below 200℃. Variable temperature experiments provide the basis for the preparation of graphene at low temperature.After variable temperature experiments, three graphene samples were produced on three different Cu–Ni alloy substrates at 400℃. The results reveal that the mass fraction of Cu in the alloy is higher, the growth rate of graphene is faster. Graphene is prepared by precipitation mechanism on the Ni surface and adsorption mechanism on the Cu surface. Because it is difficult that Ni dissolves a large number of carbon atoms at 400℃. The precipitation mechanism is difficult to play a role at low temperature. However, Cu dissolves few carbon atoms at any temperature. It is not significant that low temperature affects the growth of graphene on Cu substrate. Then, the graphene was produced on Cu substrate under the same conditions. However, the results are not perfect. After research, we believe that the catalytic activity of Ni is higher than Cu, so Ni make it easier for benzene decomposition. The mass fraction of Cu in the alloy is higher, the catalytic activity of the alloy is lower. Therefore, The mass fraction of Cu in the alloy also affects the growth rate of graphene.