The photocreation mechanisms and properties of nitrogen dangling bonds in amorphous hydrogenated silicon nitride (a‐ ) thin films are investigated. We find that the photocreation is strongly dependent on film deposition conditions, illumination temperature, and postdeposition thermal treatment. Our results suggest that H largely passivates N dangling bonds and/or precursor sites in the as‐deposited films. The N‒H bonds can then dissociate by a high‐temperature deposition or postdeposition anneal (T > 500°C), leaving behind charged N sites which become paramagnetic after exposure to UV light. The N dangling bond is found to be an electrically active point defect. Its electrical and magnetic properties can be explained by assuming that the N defect centers can be cycled between its positive, negative, and neutral charge states.