Structural, Morphological, and Optical Analysis of La-Doped NiO Films Fabricated by the Sol-Gel Spin-Coating Technique for Solid-State Electronics

La-doped nanostructured NiO films are fabricated by the sol-gel spin-coating technique on a fluorine-doped tin-oxide glass. The atomic-force microscopy of La : NiO films demonstrates a change in the grain size of the film due to doping with La. X-ray diffraction shows that La : NiO films are of a nanocrystalline nature, the crystallite size decreases as the La content increases. The optical constants are calculated by the Kramers–Kronig method. The band gap decreases at a higher La dopant content due to the quantum-confinement effect. The values of the nonlinear susceptibility of the films of first and third orders are also calculated, and these parameters behave in a similar way. A highly effective radiation-protective material based on La : NiO films is obtained.