The photoluminescence spectroscopic study of anatase TiO2 prepared by magnetron sputtering

The TiO2 film was prepared by dc reactive magnetron sputtering using a pure Ti disk as target. Raman scattering microscope, transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) were used to identify the structure. The photoluminescence (PL) spectra were measured at room temperature. Some interesting features were found on the PL spectra. The emission peak at 3.69 eV is corresponding to the vertical radiative recombination of the photo-induced electrons and holes. The PL peaks at 3.40 and 3.36 eV arise from band-to-band radiative recombination, and it can be considered as a two phonon (Eg(ν5), Eg(ν6))–one photon coupling course. The PL band from 2.8 to 3.1 eV is ascribed to surface-state trapped exciton emission, including a single phonon–one photon coupling course with the Eg(ν1) phonon attendance. The bulk oxygen impurity trapped exciton emission is the physical reason of the peak at 2.65 eV and its incident peaks from 2.4 to 2.8 eV, which consists of single, two and three phonon–one photon coupling courses with B1g(ν2) and Eg(ν1) phonon assistance.