Stretched exponential illumination time dependence of positive charge and spin generation in amorphous silicon nitride

We report for the first time on the stretched exponential time dependence of positive charge and spin generated by subband-gap ultraviolet illumination in gate-quality nitrogen-rich amorphous silicon nitride films. We have found that a stretched exponential function, which characterizes dispersive charge transport in silicon nitride, gives the best description of our experimental results. We also propose a mechanism which we believe is responsible for the creation of the positive charge and spin in the amorphous silicon nitride films.