Self-assembly of single thin Au nanoparticle chains on Si along V-groove-etched lines between micrometre-distant electrodes by dielectrophoresis

Abstract

In this study we investigated the self-assembly of 40 nm size Au colloidal nanoparticles with citrate stabilization on oxidized flat or V-groove-etched Si substrates between micrometre-distant electrodes using an ac electric field and the technique of dielectrophoresis. We demonstrated that pre-patterning of the Si surface by forming micrometre-wide V-groove lines perpendicular to the gold electrodes facilitates single nanoparticle chain formation along the V-groove-etched lines. Single thin (∼100–200 nm thick) Au nanoparticle chains 1–10 µm in length were thus formed on oxidized Si between integrated electrodes. The effect of the applied voltage and frequency of the electric field on nanoparticle chaining was investigated in detail. The selective growth along the V-grooves was interpreted by considering the electric field distribution between the electrodes. The samples were characterized by scanning electron microscopy and current–voltage measurements. The Au nanoparticle chains obtained were conductive and are interesting for applications in biomolecule sensing.