Effect of Li doping on the structural, linear and nonlinear optical properties of NiO thin films

Abstract

Nickel oxide (NiO) is a transparent conductive oxide material that has interesting physical properties, making it one of the most promising materials for a variety of modern technological applications. The interest of this work is to study the structural and optical properties of pure and Li doped NiO thin films deposited using spray pyrolysis on glass substrates. The samples were prepared at 480 °C with various concentrations of Li doping (1, 2, 3, and 5%). X-Ray Diffraction (XRD) was employed to study the structural characteristics including the crystallite size, dislocation density, and lattice strain. Meanwhile, UV visible spectroscopy was used to study the optical properties. The results revealed a polycrystalline cubic structure with (200) crystal plan being the preferred orientation for the produced films. On the other hand, (Li: NiO) films have shown a high transmittance ranging between 60 and 80%. Also, the bandgap values (Eg), were found to be significantly affected by the Li doping ratios to take values from 3.38 to 3.66 eV. Furthermore, diverse linear and nonlinear optical properties were examined. It was found that the nonlinear properties values of χ1, χ3, and n2 to were improved when lithium doping is incorporated into the NiO lattice.