Influence of Low Energy Barrier Contact Resistance in Charge Transport Measurements of Gold Nanoparticle+Dithiol-Based Self-Assembled Films

Abstract

Gold-thiol self-assembly is a widely employed strategy for engineering electronic devices using molecules and other nanostructures as building blocks. However, device behavior is expected to be governed by both building block architecture and contact effects. In order to elucidate the role of the latter in such devices, we have studied conductance of n-butanedithiol-linked Au nanoparticle (NP) films using different types of electrode configurations, namely, four-probe versus two-probe and break junctions before versus after dielectric break down of contact resistance. We find that contact resistance is governed by transport across a small barrier which can dominate device behavior when temperatures and resistances of the self-assembled devices are low. Accounting for such contact resistance reveals a more precise picture of device behavior in these regimes, including in the present system film properties near the onset of the percolation insulator-to-metal transition and beyond.