Enhancement of polaron-hopping-based a.c. conduction in semiconducting STS (Se–Te–Sn) glass by silver incorporation

Abstract

In the present work, we have synthesized novel Se_78−xAg_xTe₂₀Sn₂ (0 ≤ x ≤ 6) semiconducting glasses for improving thermally activated a.c. conduction in STS glass (x = 0). The results of the experimental analysis of thermally activated a.c. conduction have been reported in terms of frequency and temperature of Se_78−xAg_xTe₂₀Sn₂ (0 ≤ x ≤ 6) glasses. The frequency dependent experimental data of a.c. conductivity σ_ac show that σ_ac follows the Jonscher universal power law. Variation of a.c. conductivity with temperature obeys the Arrhenius relation. Further analysis confirms that the density of defect states can be determined on the basis of a correlated barrier hopping model using the frequency/temperature dependence of a.c. conductivity σ_ac (T,ω). The analysis of composition dependence of various electric parameters like potential barrier height W_m, hopping distances R_min and R_ω, dielectric constant (ε′) and the density of defect states N shows that hopping conduction is improved after silver incorporation into the parent glass. This is explained in terms of a dipolar model by considering the dipoles of Ag⁺ ions with negatively charged defect states.