Chapter 4 - Surface nanopatterning by colloidal lithography

Abstract

The design of submicron- and nanoscaled isotropic or anisotropic surfaces leads to the activation of extraordinary surface and optical properties. Colloidal lithography consists in a top-down or a combination of bottom-up and top-down nanofabrication technique adequate to process large-area substrates. Basically, the nanopattern defined by a self-assembled 2-D crystal of nanoparticles is transferred to the substrate by hole-mask etching in one or two steps using an energetic ion beam. The separation among particles, their size, the ion beam incidence angle, and the variation of azimuthal angle with respect to the colloid mask during etching determine the final nanostructure on the substrate surface. The deposition of metal coating on top of the nanopatterned surface contributes to the plasmonic properties of the samples that can find applications in many field, from optics to biological devices and from photovoltaics to metamaterials. The anisotropy of the pattern confers to these samples optical activity, which makes them attractive for nanophotonic applications. Also, the deposition of diamond-like carbon films onto such structures envisages applications in the field of hard coatings with anisotropic tribological properties. Surface energy can also be tuned for microfluidic devices and for the performance as biocompatible coatings.