Effect of the Chemical Composition of TlIn1 – xErxS2 (0 ≤ x ≤ 0.01) Crystals on Their Dielectric Characteristics and the Parameters of Localized States

Resumo

The frequency dependences of the real (ε') and imaginary (ε'') parts of the complex dielectric permittivity, the dielectric loss tangent (tanδ), and the ac conductivity (σ_ac) in the frequency range f = 5 × 10⁴–3.5 × 10⁷ Hz have been studied in the TlIn_1 – xEr_xS₂ (0 ≤ x ≤ 0.01) crystals synthesized in this work. It is found that, in TlIn_1 – xEr_xS₂, the relaxation dispersions of ε' and ε'' take place. The effect of the erbium concentration (Er) in the TlIn_1 – xEr_xS₂ crystals on their dielectric coefficients has been studied. At high frequencies, the ac conductivity of the TlIn_1 – xEr_xS₂ crystals obeys the relationship σ_ac ~ f ^0.8, which is characteristic of the hopping mechanism of the charge transfer over states localized near the Fermi level. The parameters of the states localized in the forbidden band of TlIn_1 – xEr_xS₂ and the influence of the chemical composition of the crystals on these parameters are estimated.