Silver as a dopant and as a constituent in As-Ag-Te glasses: Electrical conductivity

Electrical conductivity data (from 200 to 360 K) on fifteen glass compositions of the As-Ag-Te system are reported and discussed. The glasses were prepared using a two-stage melt-quenching method. For the (As2Te3)(1-x)Ag, glasses, features are seen in the electronic properties, corresponding to a change in the role of Ag from a dopant (for Ag less than or equal to 1 at.%), to a constituent (for Ag > 1 at.%.). At this composition, step-like changes occur, in the activation energy for electrical conductivity and in the pre-exponential factor. Examination of the data indicate that, as a dopant, Ag acts as neutral scattering centres for charge carriers. As a constituent, Ag enhances the hopping channel for conductivity near the valence band edge.