We present a new method for creating surface-confined gold nanostructures by electric field-induced scanning probe lithography (FISPL). In this technique, a gold-coated AFM tip is brought into contact with a doped SiO₂ substrate and the tip is negatively biased with respect to the substrate. Clusters of Au atoms (seeds) are concomitantly deposited onto the substrate due to the presence of extreme high electric fields (~10⁹ V/m). These seeds are subsequently developed in-situ, using a solution of HAuCl₄ and a reducing agent. We have studied the effect of important process variables, such as bias voltage, development time and reducing agent concentration on the Au nanostructure formation. We aim at gaining better control over the dimension, separation, shape (spheres, triangles, hexagons and rods) and orientation of the nanostructures at the nanometer-length scale. Our new fabrication approach is simple, can be extended to other metals, and shows promise for massively parallel implementation through anodization stamping. This new technique allows for the fabrication of nanoelectronic devices, biosensors, and surface plasmonic sensors.

SEM micrograph showing Au nanostructures on SiO₂ by FISLP deposition and subsequent chemical development.