Bias-induced anomalies in doping-modulated superlattices have been studied. The electrical properties of doping-modulated superlattices consisting of P-doped and B-doped hydrogenated amorphous silicon(a-Si:H) layers possess several anomalies that are not observed in unlayered a-Si:H samples. As bias voltage is increased, the effects of current decay with time and the magnitude of persistent photoconductivity (PPC) are increased, steady-state dark conductivity and PPC relaxation time are decreased, and the PPC v.s. illumination time curve is more rapidly saturated. The bias effects is removed almost completely after 300℃ annealing. The results are explained by electron trapping to interface states due to inhomogeneities at the p-n interface in multilayer films.
