Irradiation effects on electron trapping in thin dielectric films

This paper focuses on an analytical approach to determine the concentration of trapped electrons in thin dielectric films when they are irradiated by a charge-neutral radiation source (e.g. γ-rays) with a constant intensity. By using the band gap model, we apply a set of differential rate equations to deal with the charge buildup in the trapping level of thin dielectric films. We further assume that the change rate of electron concentration in conduction band is much slower than that in the traps. The calculations show that electron trapping is dominated by the total trap state density and the number of electron-hole pairs created in a unit time. If irradiation time is very long and the radiation source is strong, in principle, all trap states can be filled by irradiation induced electrons. However, the film still maintains electrical neutrality all the time, if radiation is charge-neutral and no external electric stress is applied