Physicals and electrochemical properties of ZnIn2S4 thin films grown by electrodeposition route

• ZnIn2S4 films were grown using electrodeposition technique of Zn–In–S system.
• Cyclovoltammetry study of binary Zn–S and In–S and ternary Zn–In–S systems.
• Study of the potential dependences on the properties of ZnIn2S4 semiconductor.
• Electrochemical impedance spectroscopy study of ZnIn2S4 thin films.
• ZnIn2S4 semiconductors are expected to have applications in photoelectrochemical technology.

We present a new work on the development of electrodeposition route for synthesis of ternary ZnIn2S4 alloy. These thin films were grown on (ITO)-coated glass substrate from acidic plating bath containing Zinc (II) Chloride (ZnCl2), Indium Chloride (InCl3) and sodium thiosulfate (Na2S2O3) at room temperature. Prior to deposition, a cyclic voltammetry study was performed in binaries (Zn–S, In–S) and ternary (ZnIn2S4) systems. The influence of various deposition potentials on structural, morphological, optical, and electrical properties of samples was investigated. X-ray diffraction patterns of samples demonstrate the presence of major crystalline phase of ZnIn2S4 at an applied potential of −1050 mV versus Ag/AgCl. Energy band gap of samples determined from optical measurements has been estimated in the range of 1.90–2.50 eV. From atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis, it was found that surface morphology, grain size and roughness were strongly influenced by varying the deposition potentials. Electrochemical impedance spectroscopy data have been modeled using an equivalent circuit approach. Flat-band potential and free carrier concentration have been determined from Mott–Schottky plot and are estimated to be around −0.72 V and 1.46 × 1017 cm−3 respectively. The film was n-type semiconductor.