The detailed calculations of optical properties of indium-doped CdO nanostructured films using Kramers-Kronig relations

The different ratios of Indium-doped cadmium oxide thin films were deposited on a glass substrate by a sol-gel assisted spin coating technique. The structure of the films was analyzed using XRD and depicts the amorphous nature of the doped films. All the films are highly transparent, and the value of transparency is around 80 % in the visible region. The optical constants were calculated based on Kramers-Kroning relations. The optical band gap value decreased with doping and is in the range of 2.73 to 2.31 eV. The enhancement in the linear optical properties such as refractive index, absorption index, and dielectric constant was also observed with an increase in the doping concentration. The linear refractive index value increased with doping concentration, and it was in the range of 2.16 to 2.62 indicates that the present sample is useful optical window applications. The nonlinear optical properties such as χ⁽¹⁾, χ⁽³⁾, and n⁽²⁾ are varying in the range of 0.005 to 0.468, 3.283 × 10⁻¹⁴² to 7.746 × 10⁻¹² esu, and 7.986 × 10⁻¹³ to 1.119 × 10⁻¹⁰ esu, respectively. The enhancement in the optical properties with increasing doping concentration suggests the present films are useful for various optical device applications. The maximum dielectric constants are varying from 4.54 to 6.42, which indicates that the present samples are suitable for optoelectronic devices. Furthermore, nonlinear optical properties were analyzed and reported.