Optical properties of Ti-doped ZnO films synthesized via magnetron sputtering

Highlights: ► Via magnetron sputtering technique, Ti-doped ZnO films were prepared. ► Optical properties in Ti-doped ZnO films were systematically investigated. ► A metallic conduction behavior was observed at higher sputtering power. ► The shift mechanism of blue emission is discussed in detail. - Abstract: Undoped and Ti-doped ZnO films were deposited using magnetron sputtering at various sputtering power. The crystal structures, surface morphology and optical properties in ZnO films were systematically investigated via X-ray diffraction (XRD), atomic force microscopy (AFM), Jasco V-570 UV/VIS/NIR and ultraviolet visible (UV–Vis) spectrophotometer. The results indicated that Ti-doped ZnO polycrystalline films with a hexagonal wurzite structure formed. Ti-doped ZnO films show more uniform and denser columnar structures with the increase of sputtering power, and a metallic conduction behavior was observed when sputtering powers is increased to 150 and 200 W. One main blue emission peak located at 445 nm was observed. However, blue emission centered at 445 nm continually blue shifted to 438 nm as sputtering power further increased. The shift mechanism of blue emission at different deposited conditions is discussed in detail.