Complex permittivity and predominance of non-overlapping small-polaron tunneling conduction process in copper indium selenide compound

Abstract

Abstract This paper presents a study of the complex permittivity of n-type copper indium selenide semiconductor compound at low temperatures down to −175 °C. Alternating current with frequency varying between 20 Hz and 1 MHz is applied to the material in order to measure the dielectric constant ɛ′ and dielectric loss D = ɛ″/ɛ′. ɛ′ is found to decrease with temperature and frequency, whereas D decreases with frequency and increases with temperature. The experimental data of ɛ″ agree with the expression ε ″ = A ω m ω , T ${\varepsilon }^{{\prime\prime}}=A{\omega }^{m\left(\omega ,T\right)}$ , where the frequency exponent m(ω, T), calculated through the relation m ω , T = ∂ ⁡ ln ε ″ / ∂ ⁡ ln ⁡ ω T $m\left(\omega ,T\right)={\left.\left(\partial \mathrm{ln}{\varepsilon }^{{\prime\prime}}/\partial \mathrm{ln}\omega \right.\right)}_{T}$ , shows a frequency and temperature dependence. The data are analyzed in light of existing theoretical models.