Effect of Composition on Charge Transport in (TlGaSe2)1–x(TlGaS2)x (0 ≤ x ≤ 1) Solid Solutions

We have synthesized polycrystalline (TlGaSe2)1–x(TlGaS2)x (x = 0–1) solid solutions and used them to grow single crystals by the Bridgman–Stockbarger method. The dielectric properties of single-crystal samples of the solid solutions have been studied in ac electric fields in the frequency range f = 5 × 104 to 3.5 × 107 Hz. We have demonstrated relaxation behavior of the complex dielectric permittivity of the (TlGaSe2)1–x(TlGaS2)x solid solutions, found out the nature of the dielectric loss in them, and identified the hopping charge transport mechanism in them. With increasing x, the electrical conductivity of the (TlGaSe2)1–x(TlGaS2)x crystals and the average distance and time of carrier hopping between localized states in the band gap of the crystals decrease, whereas the scatter in the energy of Fermi level localized states and their density increase.