Gas transport controlled synthesis of graphene by employing a micro-meter scale gap jig

The effect of gas transport inside a micrometer-scale jig gap on the growth of graphene on Cu foil located in the gap is reported. Due to the small size of the gap, a boundary layer is fully developed inside the gap, and the gas molecule transport is controlled by the molecular flow. Moreover, the conductance of the gas molecules can be tuned by decreasing the gap spacing from 1 mm to 100 mu m. First, the Cu surface is protected from the sublimation and re-deposition of Cu during pre-annealing, which results from the relatively static gas environment of the molecular gas flow. Second, suppression of the gas conductance resulted in strongly reduced overall graphene coverage with a smaller average grain size but with almost the same density as that of the graphene nuclei. Furthermore, the suppression of gas conductance leads to the formation of well-bounded graphene morphology instead of a dendritic morphology. We will describe how these results contribute to the overall understanding of the mechanism of graphene growth on Cu foil.