Influence of silver additive on electronic and ionic natures in amorphousAs2Se3

Influences of silver additive on gap states and electrical conduction in amorphous ${\mathrm{As}}_2$ ${\mathrm{Se}}_3$ are discussed through measurements of low-frequency dielectric relaxation and dc conductivity. By addition of Ag in ${\mathrm{As}}_2$ ${\mathrm{Se}}_3$, two dielectric dispersions clearly separated are observed: a fast component and a slow one. The former is caused by classical hopping of holes between localized gap centers through tail states (valence band). The density of hole trap centers increases by addition of Ag atoms. About 15%-30% of Ag additive give electrons to positively charged states ($D^{+}, C_3^{+}$) and then the interstitial-like ${\mathrm{Ag}}^{+}$ ions jump over the potential barrier between sites in the network, which causes the latter process. Electrical properties are mainly determined by these ${\mathrm{Ag}}^{+}$ ions in doped samples. Ionic transport is predicted in other elements such as Cu and Mn in chalcogenide glasses.