The ac and dc conductivities (σ ac and σ dc ) of amorphous semiconductor Sm doped Se (namely, SeSm 0.005 ) films, prepared by thermal evaporation, were measured under vacuum in a wide range of frequency and temperature. The ac conductivity versus frequency plots were analysed by considering a power law: σ ac ∝ ω s (s 1). A comparison between values of the index s with those numerically calculated from different conduction models reveals that correlated barrier hopping (CBH) is a fairly good model to describe the dominant ac conduction mechanism. The concept of the Meyer-Neldel (MN) rule in the expression of the relaxation time is considered for both ac and dc experimental data. The validity of the CBH model based on the MN (normal and inverted) rule is studied and discussed. Besides, results of the real dielectric constant (ε ), loss factor (ε ) and loss tangent (tan δ) together with the Cole-Cole diagrams and the optical (ε ∞ ) and static (ε s ) dielectric constants for a-SeSm 0.005 films are given and discussed.

The dc and ac conductivity of polycrystalline SeSm0.005 bulk samples have been measured under vacuum in the temperature range 363–93 K. The samples displayed dielectric dispersion in the frequency range 50 Hz–80 kHz. The calculated values of the exponent s of the function σ = Aωs showed that correlated barrier hopping is the suitable model to describe the ac conduction mechanism. Calculation of the real dielectric constant (ε′), loss factor (ε″) and loss tangent (tan δ) are given in the studied frequency and temperature ranges. The loss factor displayed a loss peak that gives direct evidence of the existence of a Debye relaxation type. Also, the arc shape of Cole–Cole diagrams has been used to determine and discuss the optical (ε∞) and static (εs) dielectric constants besides the macroscopic relaxation (τ0) and molecular relaxation (τ) times.