Evaluation of the inter-particle distance of gold nanoparticles dispersed on silane-treated substrates to fabricate dithiol-connected arrays

Abstract

Small tunnel junctions using gold nanoparticles (GNPs) as electrodes have been studied to fabricate single-electron devices. GNPs connected via dithiol molecules have been used as small tunnel junctions, and a two-stage dispersion method was used to fabricate dithiol-connected GNP arrays. In this process, the GNPs were fixed on silane-treated substrates by immersing the substrate in a colloidal gold solution. For fabricating dithiol-connected arrays, the inter-particle distance of the dispersed GNPs must be smaller than the GNP diameter. Consequently, the inter-particle distance controlled by the immersion time (TIM1) was evaluated. For TIM1 values exceeding 8 h, the inter-particle distance was less than the GNP diameter. A second dispersion of GNPs after treating samples with dithiol realized particle connections. For the GNP arrays produced with TIM1 values greater than 8 h, the I–V characteristics were measured at 77 K, and the yield of devices exhibiting nonlinear I–V curves was 23%.