AC conductivity and dielectric studies of Cd_0.8Sn_0.2S thin films

Abstract

Thin films of Cd 0.8 Sn 0.2 S were prepared by spray pyrolysis method. The Dc and Ac electrical conduction of Cd 0.8 Sn 0.2 S thin films was investigated in this work. Ac conductivity study of the prepared sample is reported in the frequency range 5 Hz to 13 MHz at various temperatures (300-343 K) using impedance spectroscopy. The Cole-Cole plot shows a single semicircle, indicating an equivalent circuit with a single parallel resistor R and capacitance C. Ac conductivity Ac(ω) is found to be proportional to ω s where s < 1. The value of s tends to decrease depending on the temperature. The temperature dependence of both the Ac conductivity and the parameter s is interpreted by the correlated barrier hopping (CBH) model. The temperature-dependent Dc conductivity and the relaxation frequency are found to obey the Arrhenius law having activation energy of 0.17 eV. The density of states at Fermi level is calculated and is of the order of 10 15 eV −1 ·cm −3 . Dielectric constant ε′ and dielectric loss ε″ were found to decrease with frequency and increase with temperature in the investigated ranges.