Electron paramagnetic resonance investigation of charge trapping centers in amorphous silicon nitride films

We have explored the nature of the silicon dangling-bond center in amorphous hydrogenated silicon nitride (a-SiNx) thin films, and its relationship to the charge trapping centers using electron paramagnetic resonance (EPR) and capacitance-voltage (C-V) measurements. We have investigated the quantitative relationship between the concentration of silicon dangling bonds using EPR and the concentration of charge traps, measured by C-V measurements, for both UV-illuminated and unilluminated a-SiNx thin films subjected to both electron and hole injection sequences. A theoretical framework for our results is also discussed. These results continue to support a model in which the Si dangling bond is a negative-U defect in silicon nitride, and that a change in charge state of preexisting positively and negatively charged Si sites is responsible for the trapping phenomena observed in these thin film dielectrics.