Infrared optical properties of silicon oxynitride films: Experimental data and theoretical interpretation

Abstract
Films of SiOxNy, with 0.25≲x≲2 and 0<y≲1.52, were prepared by reactive rf‐magnetron sputtering. The composition was determined by Rutherford backscattering spectrometry. Spectrophotometric measurements were conducted in the 2.5–50 μm range, and the complex dielectric function ε was extracted by computation. We interpreted ε by considering the vibrational properties of five basic Si‐centered tetrahedra, whose relative occurrence was given by the stoichiometry, and using the Bruggeman effective medium theory to average over the different tetrahedra. Theoretical and experimental data on ε were found to agree very well.