2, Nanochemistry and Nanoengineering, Aalto, , Finland
Highly filled particulate nanocomposite films consisting of metal nanoparticles in a dielectric organic or ceramic matrix have unique functional properties with hosts of applications. In most applications, a high filling factor close to the percolation threshold with control of the particle separation on the nm scale is essential because the functional properties often require short-range interaction between nanoparticles. The present talk demonstrates how vapor phase deposition techniques can be employed for tailoring the nanostructure and the resulting properties. Vapor phase deposition, inter alia, allows excellent control of the metallic filling factor and its depth profile as well as the incorporation of alloy nanoparticles with well-defined composition. We applied various methods such as sputtering, evaporation, and plasma polymerization for the deposition of the matrix, and the metallic component was mostly sputter-deposited or evaporated. Here we put emphasis on generation of the nanoparticles by means of high-rate gas aggregation cluster sources to obtain independent control of filling factor and size of the embedded nanoparticles. Results include findings from UV vis in situ measurements on the early stages of formation of plasmonic nanoparticles, formation of multiple core-shell particles and in situ control of the composition of alloy nanoparticles. Examples of fabricated nanocomposites range from optical composites with tuned particle surface plasmon resonances for plasmonic applications and magnetic high frequency materials with cut-off frequencies well above 1 GHz through sensors for volatile organic compounds and photoswitchable devices that are based on the huge change in the electronic properties near the percolation threshold to biocompatible antibacterial coatings with tailored release rate.