Electrical characterization of SnSb4S7 thin films by impedance spectroscopy

SnSb4S7 thin films were deposited on glass substrate by vacuum thermal evaporation method. The effect of annealing on the structural and electrical properties of the SnSb4S7 thin films was investigated. The X-ray diffraction analysis revealed that the powder crystallized in monoclinic structure with a preferred orientation along (2¯13¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar{2}1\bar{3}$$\end{document}) plane. SnSb4S7 thin films are polycrystalline in nature and the average grain size increases by increasing annealing temperature. Atomic force microscopy and scanning electron microscopy were used to characterize the surface morphology of the layers. Electrical properties have been investigated by ac impedance spectroscopy over a wide range of temperature up to 673 K starting from room temperature in the frequency range 5 Hz–13 MHz. The complex impedance plots display one semicircle with equivalent circuit functions as typical parallel RC. By increasing the temperature, the Impedance spectroscopy analysis shows that the resistance decreases from 107 Ω to 104 Ω. In addition, the analysis of conductivity indicates that both AC and DC conductivities of materials increase with increasing temperature The activation energy values calculated from DC conductivity and angular frequency relaxation are almost identical, indicating that the conduction mechanism was thermally activated and was assured by hopping between localized states.