L'oxynitrure de silicium: Si 2N 2O I. Attribution des absorptions du spectre infrarouge aux vibrations fondamentales

Abstract

Infrared absorption frequencies (4000 − 200 cm −1) are assigned to stretching and bending normal vibrations of the various inter-atomic bonds in silicon oxinitride. The two kinds of atoms linked to the silicon with different force constants as well as numerous results on the Si1bO1bSi bridge in materials with quite the same symmetry make Si 2N 2O a suitable material for such an investigation. The study of silicon oxygen bonds is more particulary supported by the analysis of vibrations in a “pseudo-molecule” (N 3Si1bO1bSiN 3), with a simplified computation of valence force field, and by their correlation with normal modes in the primitive cell. The assigment is also supported by a study using internal coordinates of the reduced representation of the degrees of freedom and by the behavior of the absorption bands at low temperature.