STM studies of passivated Au nanocrystals immobilised on a passivated Au(1 1 1) surface: ordered arrays and single electron tunnelling

We have employed scanning tunnelling microscopy (STM) in ultra-high vacuum (UHV) to explore the assembly and electron transport properties of an ordered layer of passivated gold clusters adsorbed onto an alkanethiol passivated Au(1 1 1) surface. The passivation of the Au(1 1 1) surface stabilises the cluster layer. STM images show ordered hexagonal arrays of the nanoparticles extending over distances >100 nm with a mean nearest neighbour spacing of 6.5 nm. I–V measurements show a strong non-linear I–V relationship, as well as equidistant steps of width ∼0.15 V above a bias voltage of ∼2 V, attributed to a Coulomb staircase, i.e., single electron charging, in this structure.