Competitive transport and percolation in disordered arrays of molecularly-linked Au nanoparticles

We explore the electrical characteristics of disordered films of strongly coupled, molecularly-linked gold nanoparticles (NPs). dc conductivity vs temperature (g vs T) measurements exhibit features that can track a number of competing transport mechanisms. Films with fewer than 6 layers show clear signatures of both activated tunneling and thermionic emission. Our linked NPs admit locally metallic transport, likely through strong quantum interactions, and at room temperature, films with 6 or more layers exhibit a transition to metallic dominated behavior. Observed g vs T dependencies have been modeled treating arrays as disordered resistor networks and using an effective medium approximation (EMA). Our results show that percolation phenomena can play critical roles in transport through NP films, particularly near metal-insulator transitions. (C) 2002 American Institute of Physics.