Fabrication and electronic properties of gold nanoparticle superlattices

Well-defined planar 1D chains and 2D superlattices of gold (Au) nanoparticles in the 1.5~9.7 nm range were successfully fabricated by a self-assembly technique. When the nanoscale ridge-and-valley structured carbon substrates were dipped in toluene solution of 3.4-nm Au nanoparticles followed by a natural dry, a planar array of 1D chains of Au nanoparticles were formed at the valleys of carbon substrates. On the other hand, the 1.5~9.7-nm Au nanoparticles protected by alkanethiols or 2,6-bis(1'- n -thioalkyl)benzimidazol-2-yl)pyridine easily formed hexagonal 2D superlattices on the flat carbon substrates, the inter-particle spacing being tuned by the ligand length and so on. It was found that for 2D superlattices consisting of large particles of ~5 nm the electron behavior was dominated by the Coulomb blockade effect at low temperature while the I–V response was ohmic at room temperature.