Operando atomic-scale study of graphene CVD growth at steps of polycrystalline nickel

Publication date: Available online 17 January 2020Source: CarbonAuthor(s): Zhiyu Zou, Virginia Carnevali, Laerte L. Patera, Matteo Jugovac, Cinzia Cepek, Maria Peressi, Giovanni Comelli, Cristina AfrichAbstractAn operando investigation of graphene growth on (100) grains of polycrystalline nickel (Ni) surfaces was performed by means of variable-temperature scanning tunneling microscopy complemented by density functional theory simulations. A clear description of the atomistic mechanisms ruling the graphene expansion process at the stepped regions of the substrate is provided, showing that different routes can be followed, depending on the height of the steps to be crossed. When a growing graphene flake reaches a monoatomic step, it extends jointly with the underlying Ni layer; for higher Ni edges, a different process, involving step retraction and graphene landing, becomes active. At step bunches, the latter mechanism leads to a peculiar ‘staircase formation’ behavior, where terraces of equal width form under the overgrowing graphene, driven by a balance in the energy cost between C–Ni bond formation and stress accumulation in the carbon layer. Our results represent a step towards bridging the material gap in searching new strategies and methods for the optimization of chemical vapor deposition graphene production on polycrystalline metal surfaces.Graphical abstract

Source: Carbon - January 17, 2020 Category: Materials Science Source Type: research