Comparative study of electrical properties of Cu2ZnxFe1−xSnS4 thin films

Highlights: • CZFTS thin films deposited by thermal evaporation under vacuum. • Presenting an original combination of referred characterization means. • Original analysis in terms of frequency–temperature dependence of AC conductivity. • Outlining a new conjoint correlation between Zn content and CFTS compound. - Abstract: Cu₂Zn_xFe_1−xSnS₄ (CZFTS) multi-component powders were synthesized by direct melting of the constituent elements and the corresponding thin films were deposited by vacuum thermal evaporation technique. The structural and electrical properties were studied by the use of X-ray diffraction and impedance spectroscopy, respectively. X-ray Diffractogrammes indicating that the transition phase from stannite structure to kesterite structure has occurred with increasing the Zn conten. Although all post-sulfurized CZFTS thin films show that only CZFTS phase was present with preferential orientation along (1 1 2) plane. Electrical properties have been investigated by ac impedance spectroscopy measured in the range from 5 Hz to 13 MHz. All the complex impedance plots display one semicircle for CZFTS thin films indicating the grain response. The analysis of conductivity indicates that both AC and DC conductivities of materials increase with increasing temperature. The frequency and temperature dependence of AC conductivity supports the correlated barrier hopping (CBH) model. All the CZFTS thin films exhibit a-p type conductivity.