Optical study of zinc blend SnS and cubic In₂S₃:Al thin films prepared by chemical bath deposition

Multilayers of zinc blend SnS crystalline thin film have been deposited onto glass substrates by a chemical bath deposition (CBD) method. The envelope method, based on the optical transmission spectrum taken at normal incidence, has been successfully applied to determine the layer thickness and to characterize optical properties of thin films having low surface roughness. Optical constants such as refractive index n, extinction coefficient k, as well as the real (ε_r) and imaginary (ε_i) parts of the dielectric constant were determined from transmittance spectrum using this method. Obtained low value of the extinction coefficient in the transparency domain is a good indication of film surface smoothness and homogeneity. To perform the heterojunction structure based on SnS absorber material, cubic In₂S₃:Al was deposited on SnO₂:F/glass as window layer using CBD with different aluminum content. Optical properties of these films were evaluated.