Nanostructured Thin Films

Abstract

Nanostructured thin films containing metal or compound conductors are scientifically intriguing and technologically important. Their optical properties are linked to applications such as spectrally selective solar absorbers, solar control glazing, angular selective filters, optical biosensors and decorative paints. Film and coating morphologies discussed include nanograined thin metal layers; cermets and polymers containing metal, oxide and boride conductor nanoparticles; oblique nanometal columns in oxide; clusters and arrays of conducting nanoparticles; nanoholes in metal, and thin metal layers on nanostructures. Situations where quasi-static effective medium theories of optical response can be used, and those where they may be inadequate due to induced currents, including surface plasmon polaritons, are outlined. The wide variety of responses provided by coupling between surface plasmons in nanoparticle arrays to form new polarization modes is outlined. Very thin nanostructured conductor layers on dielectric nanoparticles are shown to allow broadband tuning as film thickness changes. Other advantages compared to metal particles are found. Metal nanoshells in practice exemplify a common attribute of nanostructured film systems, which often embody a hierarchy of nanofeatures that combine to determine final overall optical behavior.