Photo Effects in Doping Modulated Amorphous Semiconductors

Abstract

ABSTRACTThe persistent photoconductivity (PPC) observed between 200 and 400K in npnp doping modulated hydrogenated silicon (a-Si:H) having individual layer thicknesses between 200 and 600Å iS compared with similar effects in compensated a-Si:H and in amorphous silicon/silicon nitride multilayers. The thermal activation barrier against creation of PPC in these materials, the low quantum efficiency, and the very slow recombination at 300K and higher temperatures suggest the presence of special traps that are spatially or energetically removed from the excess majority carriers. The PPC is accompanied by strongly nonohmic effects which exhibit similar metastabilities and long decay times.