Conductance resonance studies of gold cluster-assembled nanofilms

STM/STS are used to study single electron tunneling effect of gold clusters deposited on H-terminated Si crystal substrate. We find that the gold clusters are randomly stacking up on the surface of the substrate and sharp conductance resonance peaks appear when the tip of STM is positioned right above the top of one of the Au clusters while they disappear when the tip approaches towards the boundaries between the clusters on the nanofilm. Furthermore, the conductance peaks are not equidistant with fine structures and negative differential resistances (NDR) are observed at bias voltage higher than 0.3 V. By the generalized Breit-Wigner formula in a tight-binding approximation we find that in the conductance resonance the multi-peak structure may come from the interaction between Au clusters of the cluster-assembled nanofilm and the different arrangement of Au clusters may cause difference of the conductance resonance