Frequency Dispersion of Dielectric Coefficients in Low-Dimensional TlGaSe2 and TlInSe2 Single Crystals

The features of the frequency dependence of the dielectric permittivity in defect-containing semiconductors are examined. Within the framework of the Drude–Lorentz model, it is shown that the theory of permittivity dispersion in semiconductors describes the transition from dielectric to metallic behavior with increasing frequency and carrier concentration. The frequency dispersion of the dielectric permittivity of low-dimensional TlGaSe2 and TlInSe2 single crystals is studied in the frequency range from 50 kHz to 35 MHz. The regularities of defect lifetime distributions in these crystals are established. Dielectric relaxation is revealed in TlGaSe2 and TlInSe2. Using the complex dielectric modulus method, the characteristic frequencies and dielectric relaxation times of TlGaSe2 and TlInSe2, as well as their high-frequency dielectric permittivities, are determined.