INFLUENCE OF HALOGEN IMPURITIES ON CHARGE-TRANSPORT IN GLASSY SE-AS SEMICONDUCTORS

The influence of halogen impurities I, Br, and Cl on carrier transport in glassy chalcogenide semiconductors of the composition Se100-xAsx w ith x=2-10 has been studied. The Br and Cl impurities present in conce ntrations of 10(-3)-10(-2) at.% were found to increase appreciably the drift mobility of carriers. The mobility of holes increased by four o rders of magnitude. The conductivity increased by an order of magnitud e and a high stability against crystallization was maintained. An anal ysis of the experimental results showed that a change in the density o f charged intrinsic (host) states which control the drift mobility, as a result of introduction of halogen impurities is attributable to the formation of charged impurity states and to a decrease in the concent ration of the original neutral defects.