Dielectric function of Si-SiO2 and Si-Si3N4 mixtures

Abstract

Expressions for the dielectric function of Si-SiO2 and Si-Si3N4 composites are obtained by combining the Si-centered tetrahedral model of Philipp with composite-media theory. The similarity between dielectric-function spectra of a-Si and Si3N4, with scaling parameters related by the plasma sum rule and the dielectric theory of Phillips and Van Vechten is used to obtain the polarization response function for the bond part of a given tetrahedron. By treating the N and O contributions on an equal basis with Si, reasonable agreement to existing spectra is obtained for these materials over an energy range of 0–8 eV.