Topological analysis of Au particles in Au/SiO₂nanocomposite films designed for molecular conduction measurement through Voronoi diagram

Monolayered Au/SiO2 nanocomposite films with a high Au particle number density and insulating property were prepared by radio frequency magnetron co-sputtering to develop a new substrate for molecular conduction measurement. The topologies of Au nanoparticles distributed in the SiO2 matrix were statistically evaluated by morphology observation using a field emission scanning electron microscope (FE-SEM) and the Voronoi diagram of a circle set by regarding the Au nanoparticles as a circle generator. The mean Au particle size and the interparticle distance between neighbours increased with deposition time. However, the fraction of the neighbouring Au nanoparticle combinations having interparticle distance shorter than a certain length increased as the deposition time increased. The results also demonstrated that many conducting paths several tens of nanometres long can be created by attaching conductive molecules 2.4 nm long between the Au nanoparticle combinations. Thus this suggests that the nanocomposite substrate can provide a facile way to measure conducting properties of molecules.