Effects of nitridation on the characteristics of silicon dioxide: Dielectric and structural properties from ab initio calculations

The ab initio calculations on the bulk phases of SiOxN y (x = 2 - 3y/2), SiOxNy-z(NH)z (x = 2 - 3y/2; z≤ y) systems derived from doping an α-SiO2 matrix were discussed. An entire range of nitrogen concentration was found for which the structural pattern of the oxide was preserved in bulk SiON and the dielectric constant increased due to variation of the ionic polarizability. The defects which were associated with electron states near the gap were mainly centered on undercoordinated nitrogen and undercoordinated silicon. Analysis shows that the highly defective structures with highly nonuniform nitrogen distribution tend to had lower dielectric constants.