Using soft lithography to fabricate gold nanoparticle patterns for bottom-gate field effect transistors

In this study we developed an efficient method for the direct patterning of Au, through the self-assembly of gold nanoparticles (AuNPs) from colloidal solutions, onto Si substrates. We used an integrated process involving soft lithography and self-assembly to fabricate patterns of sub-micrometer AuNPs on the Si surface. By exploiting soft lithography, we obtained nanoscale patterns of self-assembled monolayers (SAMs) without the need for traditional photolithography or etching processes. After using soft lithography to pattern a SAM of (3-mercaptopropyl)trimethoxysilane on a Si surface, we immobilized AuNPs, synthesized in a two-phase system, to form the bottom layer. We then used a cross-linking agent, 1,6-hexanedithiol, to construct multiple layers of AuNP aggregates, ultimately self-assembling five-layer structures that we employed as nanoscale metal electrodes in the fabrication of organic field effect transistors (OFETs), which exhibited output characteristics, including sheet resistance, drain-source voltage, and drain-source current, similar to those of corresponding OFETs prepared using traditional processing.