Fabrication and growth of linear and nonlinear optical behaviour of Cu 2 FeSnS 4 spherical nanostructured thin films

For cost-effective synthesis of Cu 2 FeSnS 4 (CFTS) thin films, a chemical bath deposition technique was carried out at temperature of 343 K. The formation of tetragonal phase and highly oriented CFTS thin films was confirmed by XRD technique. The morphology and composition of the CFTS thin films were characterized by field emission scanning electron microscopy and EDX techniques. Linear and nonlinear optical studies of the CFTS thin films were executed to determine a future device application. The chemically prepared CFTS thin films reveal a direct energy gap which decreased from 1.54 to 1.31 eV with increasing the thickness. The nonlinear optical constants of the chemically prepared CFTS thin films such as the nonlinear absorption coefficient β c , the nonlinear refractive index n 2 and the third-order susceptibility χ (3) were evaluated and analysed.