Impact of titanium ions in the hexagonal nanostructured ZnO thin films

ZnO thin films containing different ratios of Ti metal were prepared by the DC/RF sputtering technique. XPS analysis showed the presence of Ti content in the range from 0.9 to 1.5 at.%, and Ti was existed as Ti 4+ states. Zincite phase has been detected by XRD technique through all samples and the crystallite size, the strain, and the dislocation density were estimated. Surface morphology and roughness were examined by atomic force microscopy. Optical absorbance and optical band gap were measured and determined. The optical band gap is proposed to be direct and varied from 3.25 to 3.282 eV as the Ti content increase. Photoluminescence properties show a highly intense peak at 412 nm related to the transition from shallow donor level to valence band comes from the interface traps through the grain boundaries.