Modeling charge transport in gold nanogranular films

Cluster-assembled metallic films show interesting electrical properties, both in the near-percolation regime, when deposited clusters do not form a complete layer yet, and when the film thickness is well above the electrical percolation threshold. Correctly estimating their electrical conductivity is crucial, but, particularly for the latter regime, standard theoretical tools are not quite adequate. We therefore developed a procedure based on an atomically informed mesoscopic model in which ab initio estimates of electronic transport at the nanoscale are used to reconstruct the conductivity of nanogranular gold films generated by molecular dynamics. An equivalent resistor network is developed, appropriately accounting for ballistic transport. The method is shown to correctly capture the nonmonotonic behavior of the conductivity as a function of the film thickness, namely, a signature feature of nanogranular films.