▎ 摘　　要

Graphene is deposited on polycrystalline Co film by radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD), and the effect of deposition time on the crystallinity of graphene, such as graphitic degree and in-plane crystallite size, is explored. The findings are that graphene can be obtained on polycrystalline Co film for only 15 s, suggesting that a direct growth mechanism plays an important role in the formation of graphene. The first-principles density functional theory (DFT) results also reveal that the graphene is more easily formed on Co via a surface direct growth mechanism than that via a precipitation mechanism. Our studies are critical in guiding the graphene growth process as we try to achieve the highest quality graphene for electronic devices.