Millimeter sized graphene domains through in situ oxidation/reduction treatment of the copper substrate

In chemical vapor deposition of graphene, low nucleation density and large domain sizes are desirable. In the particular case of growth on copper, throughout recent years, several works have reported the oxidation of the substrate through various means, which leads to a reduced nucleation density. In this work, an in situ oxidation and reduction treatment is explored, establishing its connection with the removal of carbon impurities from the copper bulk, as well as clarifying the role of these impurities as graphene nucleation sites. The extent of the contribution of these impurities to the growth of graphene is inferred by experiments using carbon-13 methane feed. The effect of the oxidation and reduction treatment on the substrate’s surface roughness is also addressed. Lastly, the synthesis recipe based on this treatment is supplemented with a growth stage splitting, an increased argon flowrate and a short etching stage, resulting in millimeter sized hexagonal graphene domains (diameters 2–3 mm) with improved electrical transport properties. Thus, the deposition process presented here stands out on account of its streamlined nature, which makes it an attractive candidate for industrial scale-up.