Modifying the Dielectric Properties of the TlGaS2 Single Crystal by Electron Irradiation

Abstract: The dielectric properties and ac conductivity of an electronically irradiated layered TlGaS2 single crystal are studied in the frequency range of 5 × 104–3.5 × 107 Hz. It is established that electron irradiation of TlGaS2 single crystal samples with doses of 2 × 10l2 to 2.4 × 1013 e/cm2 leads to a decrease in the real component (ε') of the complex dielectric permittivity in a high-frequency region (f > 106 Hz) and an increase in its imaginary component (ε''), the dielectric loss tangent (tanδ), and ac conductance (σac) across the layers in the entire studied frequency range. At irradiation doses of 2 × 10l2 to 2.4 × 1013 e/cm2, losses in the reach-through conductivity of TlGaS2 occur, and, as the electron irradiation dose accumulates, the dispersion of ε'' and tanδ increases significantly. In the frequency range of f = 5 × 104–2 × 107 Hz, in the irradiated TlGaS2 samples, the ac conductivity changes according to the law σac ~ fn (where n = 0.7–0.8), which is typical of the hopping mechanism of charge transfer via localized states near the Fermi level. The parameters of localized states in TlGaS2 (the density of the states near the Fermi level and their energy spread) are estimated versus the electron irradiation dose. © 2020, Pleiades Publishing, Ltd.