Facile deposition and study of substrate temperature effect on the structural and physical properties of Cu₂FeSnS₄ (CFTS) thin films

Chalcogenide thin films of Cu₂FeSnS₄ (CFTS) were deposited through spray pyrolysis method, and effect of substrate temperature on the structure, morphology, optical, and electrical properties of the thin films was investigated. The samples were characterized by X-ray diffraction (XRD), UV–Vis spectroscopy, field emission scanning electron microscopy, and electrical measurements. XRD results describe the existence of the stannite phase of CFTS thin films, which is modified after increasing the substrate temperature. All polycrystalline thin films show peaks related to (112), (204), and (116) planes. FESEM images represent growth of the grains for higher substrate temperatures. Hall and Seebeck effect experiments confirm p-type conduction in all of the samples. The carrier density is found in the order of magnitude of 10²⁰ cm⁻³ which increases by increasing the substrate temperature. Optical band gap measurements based on UV–Vis spectroscopy describe the values between 1.33 and 1.54 eV for all the samples. It is found that the CFTS absorber layers can be fabricated via facile method and their physical properties are adjustable through regulation of substrate temperature.