The Electrical Conduction at Early Stages of Cluster-Assembled Films Growth

Electrical conduction in Fe, Pd, Nb, W and Mo cluster-assembled films was investigated in-situ, during their growth by supersonic cluster beam deposition. We observed for clusterassembled films resistivity values several orders of magnitude larger than corresponding bulk, as well as an increase of resistivity by increasing the film thickness, in contrast to the behaviour of atom-assembled metallic films. This suggests that nanoscale morphology arising by growth dynamics of cluster-assembled films, such as the minimal cluster-cluster interconnection and the evolution of surface roughness with thickness, may play a crucial role in the observed behaviour. Theoretical models based on non-isotropic 3D distributions of clusters into the film would help for a deeper understanding of the behaviour of cluster-assembled films compared to atomassembled ones. Benefits are expected in the technological field of devices performing electrical read-out on active nanostructured layers, as in the case of chemoresistive sensors.