Synthesis of large area, homogeneous, single layer graphene films by annealing amorphous carbon on Co and Ni

Abstract

The synthesis of large area, homogenous, single layer graphene on cobalt (Co) and nickel (Ni) is reported. The process involves vacuum annealing of sputtered amorphous carbon (a-C) deposited on Co/sapphire or Ni/sapphire substrates. The improved crystallinity of the metal film, assisted by the sapphire substrate, proves to be the key to the quality of as-grown graphene film. The crystallinity of the Co and Ni metal films was improved by sputtering the metal at elevated temperature as was verified by X-ray diffraction (XRD). After sputtering of a-C and annealing, large area, single layer graphene that occupies almost the entire area of the substrate was produced. With this method, 100 mm 2 -area single layer graphene can be synthesized and is limited only by the substrate and vacuum chamber size. The homogeneity of the graphene film is not dependent on the cooling rate, in contrast to syntheses using polycrystalline metal films and conventional chemical vapor deposition (CVD) growth. Our facile method of producing single layer graphene on Co and Ni metal films should lead to large scale graphene-based applications.

Growth Mechanism for Low Temperature PVD Graphene Synthesis on Copper Using Amorphous Carbon

“…The proposed growth mechanism can also explain the claim of inability of Graphene growth on Copper thin film using this method as reported by others1617. An attempt to achieve similar synthesis at comparatively lower temperature is presented and the growth mechanism is discussed for the same.…”

Dense Arrays of Highly Aligned Graphene Nanoribbons Produced by Substrate‐Controlled Metal‐Assisted Etching of Graphene

“…[ 40,42 ] Raman spectra were substantially different in the low etching density area, showing a broad D band overlapping with G band (Figure 3 a), a feature typically observed on spectra of amorphous carbon thin fi lms. [ 43,44 ] Amorphous carbon might have been formed by the reaction of the graphene with the methane gas evolved at the high-etching-density areas. Owing to a relatively high annealing temperature (1100 °C) compared with the typical CVD growth temperature of graphene and nanotubes, the carbon-catalyzed decomposition of methane on top of the graphene probably proceeds at a signifi cant rate, thus forming an amorphous carbon fi lm.…”

Porous platinum mesoflowers with enhanced activity for methanol oxidation reaction

“…The ratio between the forward (I f ) and reverse (I b ) anodic peak current densities, I f /I b , has been used to describe the tolerance of a catalyst to the accumulation of carbonaceous species [35][36][37][38][39][40]. Low I f /I b ratio is an indication of poor oxidation of methanol to carbon dioxide during an anodic scan and accumulation of carbonaceous residues on the catalyst surface.…”