A.C. conductivity of bulk glassy chalcogenides

The a.c. conductivity of amorphous Se, Se₉₀Ge₁₀, Se₇₅Ge₂₅, As₂Se₃, As₂S₃, and As₄₅Te₄₀Ge₁₅ has been measured at room temperature in the 20 MHz–35 GHz range. The results display a contact effect we explicit. For the six materials, the conductivity is roughly proportional to ω^s with $\text{s}{}^{\mathrm{\approx }}\text{1}$ up to the microwave region (no saturation is observed). The experimental results are analysed with regard to the electronic and the atomic contributions but a better estimate of some parameters is necessary to confirm any model.