Defect Structures in Graphene Grown by Chemical Vapor Deposition on Nickel(111)

This thesis examines the growth of graphene by chemical vapor deposition (CVD) on Ni(111) and the nickel carbide (Ni2C) reconstruction of Ni(111) with scanning tunneling microscopy (STM). The structural evolution of graphene on Ni(111) is investigated as a function of growth temperature. Low temperature (400--500 °C) growth results in a continuous but highly defective film with small ordered graphene domains and disordered domains composed of Stone-Wales-like defects. As the growth temperature is increased, the disordered domains shrink leaving small clusters of defects alongside epitaxially matched graphene. The presence of excess carbon, in the form of Ni2C, prevents graphene from adopting the preferred 1x1 configuration and leads to grain rotation. STM measurements show that residual Ni2C domains are present under rotated graphene. Nickel vacancy islands are observed at the periphery of rotated grains and indicate Ni2C dissolution after graphene growth. This work highlights the role of the graphene-substrate interaction on formation of defects in CVD-grown epitaxial graphene.