Silicon oxynitride films of various compositions were grown in situ by RF-plasma sputtering. The high-resolution electron-energy-loss spectra were analyzed in the framework of the dielectric theory after addition of a characteristic background structure. The evolution of the energy-loss peaks as a func-) concentration ratio clearly exhibits a one-mode behavior. This suggests that silicon oxynitride is characterized by a mixture of Si-0 and Si-N bonds at the atomic level. An exponential frequency shift of the main peak is observed as a function of the concentration ratio. Infrared optical parameter values are provided for thermal and RF-plasma sputtered oxides, and for two compositions of RF-plasma SiO N [y/(y +x) =0.37 and 0.80] silicon oxynitrides.

Multilayered structures were prepared by growing SiOXNy and SiOX films uponAl substrates. Different stoichiometries of the oxinitride layers were obtained by a reactive R.F sputtering technique. The infra -red reflectance experiments show that such multilayered structures should be better adapted for application to radiative cooling devices than single layers made with the same materials. This is explained by the presence of strongly absorbing radiative surface and interface modes which appear in the Reststrahlen frequencies because of the multilayered geometry. We performed ATR experiments so as to detect the presence of these modes and to demonstrate their correlation with the reflectance spectra.

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