Growth Dynamics of Single-Layer Graphene on Epitaxial Cu Surfaces

The growth of single-layer graphene on Cu metal by chemical vapor deposition (CVD) is a versatile method for synthesizing high-quality, large-area graphene. It is known that high CVD temperatures, close to the Cu melting temperature (1083 °C), are effective for the growth of large graphene domains, but the growth dynamics of graphene over the high-temperature Cu surface is not clearly understood. We investigated the surface dynamics of the single-layer graphene growth by using heteroepitaxial Cu(111) and Cu(100) films. At relatively lower temperatures, 900-1030 °C, the as-grown graphene showed the identical orientation with the underlying Cu(111) lattice. However, when the graphene was grown above 1040 °C, a new stable configuration of graphene with 3.4° rotation became dominant. This slight rotation is interpreted by the enhanced graphene-Cu interaction due to the formation of long-range ordered structure. Further increase of the CVD temperature resulted in graphene which is rotated with wide angle distributions, suggesting the enhanced thermal fluctuation of the Cu lattice. The band structures of CVD graphene grown at different temperatures are well correlated with the observed structural change of the graphene. The strong impact of high CVD temperature on a Cu catalyst was further confirmed by the structural conversion of a Cu(100) film to Cu(111) which occurred during the high-temperature CVD process. Our work presents important insight into the growth dynamics of CVD graphene, which can be developed to high-quality graphene for future high-performance electronic and photonic devices.