Effect of the chemical composition of TlIn$_{1-x}$Er$_{x}$S$_{2}$ (0 $\le x\le$ 0.01) crystals on their dielectric characteristics and the parameters of localized states

The frequency dependences of the real $(\varepsilon)$' and imaginary $(\varepsilon)$" components of the complex dielectric constant, tangent of dielectric loss (tan$\delta$) and ac conductivity $(\sigma_{\operatorname{ac}})$ of the obtained TlIn$_{1-x}$Er$_{x}$S$_{2}$ (0 $\le x\le$ 0.01) crystals have been studied in the frequency range $f$ = 5 $\times$ 10$^4$ - 3.5 $\times$ 10$^7$ Hz. It is established that in TlIn$_{1-x}$Er$_{x}$S$_{2}$ a relaxation dispersion of $\varepsilon$' and $\varepsilon$" takes place. The effect of erbium concentration (Er) in TlIn$_{1-x}$Er$_{x}$S$_{2}$ crystals on their dielectric coefficients was studied. In the high frequency range, the ac conductivity of TlIn$_{1-x}$Er$_{x}$S$_{2}$ crystals obeyed the $\sigma_{\operatorname{ac}}\sim f^{0.8}$ law, which is characteristic of a hopping charge transfer mechanism at states localized near the Fermi level. The parameters of states localized in the band gap and the influence of the chemical composition of the TlIn$_{1-x}$Er$_{x}$S$_{2}$ crystals on these parameters are estimated.