Effects of impurities on the properties of amorphous silicon

Oxygen and nitrogen impurities increase the electrical conductivity of hydrogenated amorphous silicon (a-Si:H) films due to their donor-like behavior. An appropriate amount of boron doping compensates those donors so that the conductivity is restored to the original value unless alloying effects appear such as band gap widening. The creation of light-induced defects does not seem to be affected by the impurities, because the effects of the impurities are not obvious after light-soaking. The results indicate that the major effect of the oxygen and nitrogen is the creation of donors due to their small fraction and that a large amount of the rest impurities with inactive configurations show no other significant effect until alloying effects appear.