Dielectric dispersion of polycrystalline ferroelectric-semiconductor Sn2P2S6 films

The frequency dependence of real (ε′) and imaginary (ε″) components of the complex dielectric permittivity has been determined for tin-thiohypodiphosphate Sn2P2S6 films in the temperature region from 150 to 400 K. There are two dielectric relaxation regions in the frequency range between 10−1 and 107 Hz. The high-frequency dielectric dispersion region at 103-107 Hz exhibits Debye type behaviour due to a semiconductor-metal interface barrier similar to a Schottky barrier. At low frequencies from 10−1 to 103 Hz, dielectric response is nearly a “flat loss” at least in the low-temperature region. At elevated temperature, the flat dispersion region disappears and a strong linear decrease of ε″ (ω) is observed because of the dc conductivity.