Electrical conduction and persistent photoconductivity (PPC) effect in sandwich type a-Si:H doping-modulated superlattices have been studied. The electrical transport mechanism in sandwich a-SiLH superlattices varies from the exponential to the power law with p-layer doping concentrations while n-layer fixed (200ppm). And PPC effect was first observed in sandwich superlattices. Teh PPC effect in sandwich superlattices is caused by special centers which are in the p-layers near the n-p interfaces, or by enhancement of hopping probabilities in the p-layers. The PPC decay and annealing behaviors with electrical transport mechanisms perpendicular to the multilayers, which might depend on p-layer doping concentrations, are discussed.
