Low temperature growth of complete monolayer graphene films on Ni-doped copper and gold catalysts by a self-limiting surface reaction

We report on the fabrication of completely uniform monolayer graphene on a metal thin film over a 150 mm Si substrate at a low temperature of 600 °C by inductively coupled plasma-enhanced chemical vapor deposition (ICPCVD). Through novel use of bimetallic catalyst such as CuNi and AuNi alloys we were able to control catalytic reaction at the metal surface and grow complete monolayer graphene with a Ni content less than 20 at.%. We also found that the 2D/G intensity ratio in the Raman spectra was almost invariant with growth time and the C 1s peak in the XPS spectra was observed only at the metal surface. This implies that monolayer graphene was possibly grown on these Ni-doped copper and gold catalysts by a self-limiting surface reaction under our CVD condition. From DFT calculations, it was shown that the catalytic activity of normally inactive Cu and Au could be enhanced through the addition of Ni atoms at surface sites, providing graphene growth at lower temperatures than pure Cu or Au. The carrier mobility of graphene films grown on these CuNi and AuNi alloy catalyst was measured to be over 9000 cm2 V−1 s−1 at room temperature, which is comparable to that of CVD graphene film grown on Cu foil. Therefore, we suggest an efficient way in growing a complete monolayer graphene on thin films at low temperatures, which could be a key issue in the application of graphene devices.