Metal-modified amorphous arsenic selenide films were prepared by spinning a solution containing an amine salt, thioacetamide and chlorides of the impurifying metals Zn, In, Sb, Co and V on thoroughly cleaned flat glass substrates. X-ray analyses show excess total metal components for the V- and Co-modified films whilst the In-, Zn- and Sb-doped films are selenium-rich. The electrical conductivity and optical absorption measurements reveal that only the transition metals V and Co have significant effects on the transport. A narrowing of the optical band gap as well as the conductivity activation energy is observed as the impurity concentration is increased. The room temperature electrical conductivity increases from 10 11(Ω m) 1 to 10 7(Ω m) 1 for samples doped with vanadium and cobalt to a concentration of about 2 at%. The results are interpreted in terms of the charged dangling bond defect models. At concentrations beyond 2–3 at%, the shift of the Fermi level becomes virtually independent of the impurity concentration pointing to a model in which an impurity level appears and is rigidly connected to one of the bands.
Physica B Condensed Matter 07/1993; 190(2-3):136-144. DOI:10.1016/0921-4526(93)90458-I