AC electrical conductivity and dielectric studies on evaporated nanostructured InSe thin films

Nanostructured InSe thin films were prepared by thermal evaporation technique under a vacuum of 10-4 Pa. The AC electrical conductivity and dielectric properties of the prepared films have been investigated in the frequency range from 100 Hz to 5 MHz and in the temperature range 293-393 K. The frequency dependence of σ(ω) follows the Jonscher's universal dynamic law with the relation σ(ω) = σdc + A ωs, where s is the frequency exponent. It is found that s has value ≤1 and decreases with increasing temperature suggesting a hopping conduction mechanism. It is found also that ln σac(ω) increases linearly with the reciprocal of the absolute temperature. This suggested that the AC conductivity is thermally activated process with AC activation energy decreased with increasing frequency. In spite of the absence of the dielectric loss peaks, application of the dielectric modulus formalism gives a simple method for evaluating the dielectric relaxation time and the activation energy of the dielectric relaxation. © 2013 Elsevier B.V. All rights reserved.