Influence of lithium ions on the structural, optical, and electrical properties titanium niobium oxide thin films

This work successfully prepared TiO2:Nb thin films with various Li ions content using the sol-gel and immersing method. These films' crystal, morphological, optical, and electrical properties are investigated to study the impact of Li ions using various techniques starting with X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis spectrophotometer, and four-point probe. XRD pattern and SEM micrographs of the thin films referred to the tetragonal crystal structure; it was found that the crystallite size increased by adding Li ions in the TiO2:Nb thin films. The transmittance value and the bandgap energy are reduced by introducing the Li ions in the films; in contrast, the refractive index and the extinction coefficient are boosted. Finally, the conductivity value is enhanced depending on the Li ions content due to increasing the charge carriers' concentration in the thin films, where the highest possible value was achieved at 5 wt% of Li ions.