Atomic-scale investigation of the graphene growth on flat and stepped (001) nickel surfaces
Peressi M., Zou Z., Carnevali V., Patera L.L., Jugovac M., Sala A., Panighel M., Cepek C., Comelli G., Africh C.
II - Fisica della materia
GSSI Ex ISEF - Aula C - Venerdì 27 h 09:00 - 12:00
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On (001) nickel grains, a continuous graphene layer can form by chemical vapor deposition on both flat terraces and, more interestingly, stepped regions. On flat terraces, due to the mismatch with the substrate, a variety of moiré patterns with different corrugation are present, whose atomic-scale structure is well characterized by combining scanning tunneling microscopy (STM) images and density functional theory (DFT) simulations. Segregation at the graphene/substrate interface of additional carbon atoms upon cooling, changes the carbon/nickel interplay, tailoring the formation of nanostructured 1D or 2D regions of free-standing--like graphene, evidenced by STM and spectroscopic results and extensive numerical investigations also including Monte Carlo simulations. At step edges, peculiar growth mechanisms leading to a smooth carpeting and downhill landing of graphene are unveiled by STM time-series acquired up to video rate and rationalized by DFT.