Effect of Sulphide Concentration on Some Physical Properties of Cu₂BaSnS₄ Nanostructured Thin Films

In this work, Cu2BaSnS4 thin films were deposited on soda-lime glass by successive ionic layer adsorption and reaction (SILAR) technique at different concentrations of sodium sulfide, with a thickness of about 350 ±10 nm measured by the gravimetric method. The thin films structural and morphological properties were investigated using X-ray diffraction (XRD), Raman spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM), and Atomic Force Microscopy (AFM), as well as optical properties using a UV-Vis spectrophotometer at the wavelength range (300-900) nm. Optical band gap of CBTS thin films decreased from (1.818 to 1.673) eV when concentrations of sodium sulfide increased from (0.04 to 0.12) M. The Cu2BaSnS4 (CBTS) films have a high absorption coefficient (α 104 cm-1), indicating allowed direct electron transmission. XRD measurements of Cu2BaSnS4 (CBTS) films revealed a trigonal crystal structure. The XRD pattern preferred the (104) orientation, which has a high intensity and indicates that crystallization is most likely to occur along this plan. Raman spectroscopy of CBTS thin films revealed a protruding peak at ~341 cm-1. The morphological findings and FE-SEM photographs of the thin film surface revealed various structures and forms, one of which resembled cauliflower. Electrical tests revealed the conductivity of (p-type). The calculated electrical conductivity of CBTS thin films was found in the range of 0.06-0.242 (Ω.cm)-1. Based on the findings of the study, the Cu2BaSnS4 (CBTS) thin films look to be an excellent choice for an absorber layer in solar cells.