Frequency dependence of conductivity in the layered In$_4$Se$_3$ crystals

Abstract

The frequency dependence of conductivity in In$_4$Se$_3$, pure and with copper admixture crystals, in the region of nitrogen temperatures is investigated. It was found out that variable length hops on the localized levels in the vicinity of Fermi level is pre-dominant mechanism of charge transfer in the crystals. For pure In$ _4$Se$ _3$ crystals the density of localized states is $10^{17}-10^{18}$ eV$^{-1}\cdot$cm$^{-3}$, the mean hop length is 220--350 {\AA}. The reasons for the occurrence of localized states are considered within the model of a layered crystal as a quasi-disordered system.