Microscopic origin of the light-induced defects in hydrogenated nitrogen-rich amorphous silicon nitride films

The electron photo-excitation from the K^- state and its subsequent trapping by K⁺ state is probably at the origin of the silicon dangling bonds (K⁰) formation during broad-band UV illumination of the N-rich amorphous silicon nitride films. Because the photo-excited electron will move towards the metal electrode the positive charge is expected to accumulate near the nitride-silicon interface with illumination time. Our data also suggest that the N-H group may be at the origin of the nitrogen dangling bonds creation in N-rich films.