Nicolas Reckinger, Alexandre Felten, Cristiane Nascimento Santos, Benoît Hackens, Jean-François Colomer
The growth of graphene by atmospheric pressure chemical vapor deposition in a vacuum-free system is investigated. The emphasis is put on the necessity of hydrogen presence during the graphene synthesis and during the cooling step. It is observed that, in the absence of hydrogen during the growth step or during cooling at slow rate, the surface of the copper catalyst is strongly oxidized, with weak carbon coverage, consisting mostly of oxidized and amorphous carbon. The oxidation plausibly originates from the inevitable occurrence of residual oxygen in the reactor's atmosphere. Graphene can be grown only when hydrogen is admitted during the synthesis step. After formation, it is preserved from the destructive effect of oxygen if its exposure at high temperature is minimized by fast cooling or hydrogen. Under these conditions, micrometer-sized hexagon-shaped graphene domains of high-quality structural quality are obtained.
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http://arxiv.org/abs/1303.3951
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