Model for the radiation degradation of polycrystalline silicon films

The degradation of polycrystalline silicon (Poly-Si) films, subjected to 20-MeV alpha-ray irradiation, is studied. To investigate the radiation source dependence, 20-MeV proton and 1-MeV electron irradiation have been performed as well. The damage of alpha-rays is one and three orders of magnitude larger than for protons and electrons. The radiation source dependence of the performance degradation is attributed to the difference of mass and the probability of nuclear collisions for the formation of lattice defects. It is concluded that the combination of the induced lattice defects in the grain itself and the interface state density at its boundary are mainly responsible for the degradation of the Poly-Si films by high-energy particle irradiation. The degradation of the Poly-Si films can also be explained by a finite grain-bulk dynamic resistance r_c and a large-barrier dynamic resistance r_SCR based on the Schottky barrier diode degradation mechanism.