Frequency-dependent dielectric coefficients of TlInS₂ amorphous films

Abstract

The frequency dispersion of the loss tangent (tgδ) and the ac conductivity (σac) of amorphous films prepared by evaporation of TlInS₂ has been investigated at frequencies f = 5⋅10⁴…3.5⋅10⁷ Hz. It is shown that, at f > 10⁶ Hz, relaxation losses take place. It is established that the hopping conduction near the Fermi level occurs in TlInS₂ amorphous films at frequencies up to 3⋅10⁶ Hz. The density of localized states at the Fermi level, the mean time for phonon-assisted tunneling, and the hopping distance have been evaluated for polymorphic TlInS₂ films. For frequencies above 10⁷ Hz, σac( f ) ~ f₂. Such a behavior is caused by optical transitions in TlInS₂ amorphous films.