Nanostructured thin films - A critical review

Nanostructured thin films containing metal or conducting oxides underpin some existing technologies. Based on recent advances they will also enable many emerging opportunities. The optical properties from different nanostructures are linked to examples including, spectrally selective solar absorbers, solar control glazing, angular selective filters, optical bio-sensors, and decorative paints. This review will cover studies of various film and coating morphologies including cermets, and polymers containing metal or oxide conductor nanoparticles, oblique nano-metal columns in oxide, clusters and arrays of conducting nanoparticles, nanoholes in metal, granular metal networks and thin metal layers on nanostructures. Situations where quasi-static effective medium theories of optical response can be used and those where they are inadequate due to surface plasmon polariton effects will be compared. The latter includes very fine scale nano-features. Coupling between surface plasmons to form new modes is an important consideration. A brief look will also be given into an important new field - very thin metal films on nanoparticles which allow broad band tuning as thickness changes. The nanostructure within such films is quite influential.