Coalescence and epitaxial self-assembly of Cu nanoparticles on graphene surface: A molecular dynamics study

A detailed understanding of surface decoration and interconnecting technologies is essential in realizing high-performance functional devices incorporating metal nanoparticle/graphene nanohybrids. This study employs classical molecular dynamics (MD) simulations to investigate the formation of amorphous copper (Cu) layers on a graphene surface via the collision, coalescence and nucleation of individual Cu nanoparticles (NPs) at temperatures in the range of 300–1300 K. The results indicate that the coalescence and melting temperatures are both sensitive to the particle size and the presence of the substrate. Moreover, an epitaxial interaction is found between the Cu NPs and the graphene substrate, in which mobile Cu atoms are captured and dragged to the graphene surface to produce self-assembled NP layers via a nucleation process. A series of structural evolutions and phase transitions are revealed during the thermalization process of the NPs. Finally, the results show that the presence of the substrate and associated contact epitaxy phenomenon play a key role in governing the structural morphology and thermal behavior of the Cu NP-based thin film.