Ellipsometric characterization of SiOx films with embedded Si nanoparticles

In this work we present results on the ellipsometric study of SiOx films in the spectral range of 280–820 nm. The films were deposited by vacuum thermal evaporation of SiO onto Si substrates heated at 150 °C. To stimulate the formation of silicon clusters in the oxide matrix the films were annealed at temperatures 700, 1000 and 1100 °C in argon for 5, 15 and 30 min. By applying the Bruggeman effective-medium approximation theory and using multiple-layer optical models, from the ellipsometric data analysis the thickness, complex refractive index and composition of the films, as well as the size of the embedded Si nanocrystallites have been determined. Atomic-force microscopy imaging showed a very smooth surface, the roughness value of which correlated well with the top-layer thickness, determined from the ellipsometric data analysis.