Detailed investigation of optical linearity and nonlinearity of nanostructured Ce-doped CdO thin films using Kramers-Kronig relations

Sol-gel-assisted spin coating technique has been employed to deposit Ce-doped cadmium oxide films (CdO) thin films on a glass substrate. Structural analysis carried out by XRD revealed that the films are polycrystalline and crystallize in a cubic structure. The preferential directions for the CdO growth are (2 0 0), and (2 1 0) and doping of Ce ions inhibits the growth. In addition to XRD, Raman analysis also supports the crystalline phase with no impurities. Using the Kramers-Kronig relations, the dispersion relation is evaluated from which the refractive index and the absorption coefficient were derived. The deposited doped and pure CdO films are highly transparent. The energy gap values of pure and doped CdO films are in the range of 2.2-4.2 eV, making them suitable for optoelectronic applications. The lower values of 'n' and 'k' are making the films most significant. The dielectric constant and nonlinear optical properties showed an increasing tendency on doping Ce ions into CdO films.