Disorder and Defect Healing in Graphene on Ni(111)

The structural evolution of graphene on Ni(111) is investigated as a function of growth temperature by scanning tunneling microscopy (STM). Low temperature (400-500 degrees C) growth results in a continuous but highly defective film with small ordered graphene domains and disordered domains composed of Stone-Wales (SW)-like defects. As the growth temperature is increased, the disordered domains shrink leaving small clusters of defects alongside epitaxially matched graphene. Density functional theory (DFT) calculations indicate the crucial role of the metallic support for the healing of SW defects, as the interaction with the substrate leads to a stabilization of the reaction intermediate. This work highlights the effect of the graphene-substrate interaction on the temperature dependence of the defect concentration in epitaxial graphene on Ni(111).