Effect of transparent conducting substrates on the structure and optical properties of tin (II) oxide (SnO) thin films: Comparative study

Tin (II) oxide (SnO) thin films were deposited onto indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO) and glass substrates using the thermal evaporation technique. The X-ray diffraction (XRD) patterns revealed that the evaporated SnO film was an amorphous structure. The shape and size distributions of surface grains for SnO/ITO, SnO/FTO, and SnO/glass were investigated using atomic force microscopy (AFM). The purity of the SnO onto ITO, FTO, and glass substrates was confirmed using Raman spectra. Tauc's relation for SnO/ITO, SnO/FTO, and SnO/glass thin films indicated the occurrence of direct transitions. The redshift of the E g Opt correlated with the grown of SnO nanoparticles. The electronic polarizability, dielectric constants, energy loss functions, and optical conductivity constants were directly derived from the extinction coefficient (k), and refractive index (n). In addition, the nonlinear susceptibility χ ( 3 ) , non-linear refractive index n ( 2 ) and nonlinear absorption coefficient (βc) were valued based on the semi-empirical relation for SnO/ITO, SnO/FTO, and SnO/glass. The SnO/ITO films displayed higher nonlinear parameters than SnO/FTO films. Therefore, SnO/ITO will be a promising optical system in the nonlinear optics field.