Abstract

Composite films composed of a dielectric matrix with imbedded metal nanoparticles are primarily of interest as spectrally selective optical coatings for such applications as photothermal conversion, radiative cooling, infrared furtivity, etc. More recently, they have received attention for their non-linear optical properties.¹ Detailed knowledge of the microstructure becomes critical for the latter application as the nanoparticle size and shape (through their effect on the local field) as well as the volume fraction (filling factor) affect the magnitude of the non-linear response. Microstructural characterization of these materials generally involves TEM measurements, which can influence the microstructure through electron beam induced coalescence of the metal grains.² Alternatively, optical characterization, namely transmission measurements, have been used³,⁴, but the results are generally qualitative and thickness and filling evaluations need to be made by other methods. It is the purpose of this work to demonstrate the applicability of ellipsometric measurements to characterize fully (film thickness, nanoparticle filling, size and shape) the microstructure of these nanocomposite materials.

© 1998 Optical Society of America