Cluster-Assembled Materials: From Fabrication to Function

The deposition of preformed clusters on a substrate enables the careful control of the nanoscale topography of thin films and hence the tuning of the structural and functional properties of nanostructured surfaces and interfaces. In this article, we show that cluster beam deposition (CBD) is an effective bottom-up approach for the engineering of nanostructured thin films with tailored properties. As a prototypical example of the possibilities offered by CBD, we present and discuss in detail how fabrication parameters affect the functional properties of very important systems such as titania, zirconia, and silicon nanostructured films. The use of pulsed microplasma and magnetron cluster sources allows the control of the characteristics of the building blocks and hence of the reproducibility of the deposition process and the functional properties of the cluster-assembled systems. We discuss the implications of these mechanisms on the possibility of predicting and controlling the properties of cluster-assembled surfaces, presenting examples of applications where nanoscale morphology has a strong and direct impact on the physical behavior of the surface.