Sputter Oriented Nickel and Defect Inhibitors in Graphene

Understanding of nickel (Ni) grain size, distribution, and structure are critical parameters in a sputter-deposited Ni catalyst for achieving the desired number of graphene layers [1] grown by atmospheric pressure chemical vapor deposition (APCVD). The size and distribution of grains can be controlled by variations in sputtering parameters, but the final crystal structure and defects are not apparent until after the high temperature annealing. We analyzed the x-ray diffraction patterns in the Ni catalyst to determine effect of thermal annealing on the Ni grain size, orientation, and structural defects. Experiments have shown that in-situ sputter-deposited Ni films at 250 °C are highly oriented in the direction [111] that produced the high yield of graphene films with desired number of layers. Low defect density in a sputtered nickel (Ni) catalyst is a necessary ingredient for achieving precision number of graphene layers. These sputtering parameters can accelerate or postpone the final preferred orientation of the Ni film. A sputter temperature of 250 °C achieved complete transformation from polycrystalline film to the preferred [111] orientated film.