▎ 摘　　要

Previous work has demonstrated that the growth temperature for the chemical vapor deposition of graphene can be decreased by tailoring the precursor composition. Here, we fix the precursor as CH4 and instead explore the effects of the catalyst facet, synthesis conditions, and growth rate on the quality of graphene grown at reduced temperature on Cu. We find that in order to obtain graphene films with low defect density, it is critical to maintain a slow growth rate, which is achieved using a low CH4 partial pressure. Furthermore, growth on Cu(111) is more efficient than on other low index Cu facets. Using optimized growth conditions, we achieve high-quality continuous monolayer graphene films, with a low nucleation density of 4 x 10(-2) mu m(-2) and a negligible Raman D:G ratio, at 750 degrees C, which is 125 degrees C cooler than previous reports achieving full graphene coverage on Cu. The field-effect mobility is 2600 cm(2) V-1 s(-1) at a carrier concentration of 10(12) cm(-2), and low-energy electron microscopy indicates that there is one predominant graphene crystallographic orientation with respect to the underlying Cu(111). These results demonstrate that by tailoring the catalyst facet and growth rate, the temperature required to achieve high-quality continuous films, using a given precursor, can be reduced without sacrificing the excellent properties of graphene.