Spectroellipsometric characterization of plasma-deposited Au fluoropolymernanocomposite films

Nanocomposite thin film structures are presently being studied because of t heir interesting nonlinear optical properties. The microstructure of plasma -deposited nanocomposite films consisting of gold particles embedded in a p lasma-polymerized fluorocarbon matrix was fully characterized using a gener alized Maxwell-Garnett effective medium approach applied to ellipsometric d ata. The particle size dependence of the dielectric properties of gold was treated classically using a broadening parameter, A, equal to 0.25, as dete rmined from transmission electron microscopy analysis. In general, the mode l predicted correctly the dependence of microstructural characteristics on glow discharge parameters and post-deposition thermal treatments. However, careful interpretation of the model fit parameters is necessary in both the high gold volume fraction limit and small particle size limit. For the for mer, misleading results with respect to particle size and shape may be obta ined due to aggregation effects, the onset of which was determined to occur at a gold volume fraction of about 30%. For the latter, deviations from th e classical description of the permittivity of gold nanoparticles (occurrin g for particles smaller than 7 nm) can lead to misleading results with resp ect to particle shape. (C) 1999 American Vacuum Society. [S0734-2101(99)034 03-X].