Prevalence of Coulomb blockade in electro-migrated junctions with conjugated and non-conjugated molecules

Conduction of electro-migration gap junctions coated with various organic molecules is studied to expose the prevalence of different transport processes. The principal comparison made here is between molecules with conjugated versus non-conjugated backbones. Coulomb blockade (CB) is observed in all junctions, including bare junctions and those with non-conjugated molecules, but at significantly lower prevalence than for conjugated molecules. Importantly, CB with high charging energy is seen almost exclusively on junctions with conjugated molecules. These results indicate that CB is ubiquitous in molecular electro-migration junction transport with prevalence that should be characterized using large numbers of samples.