X-ray photoelectron spectroscopy study of thin TiO2 films cosputtered with Al

In this study, titanium dioxide (TiO2) films were fabricated by cosputtering of a titanium (Ti) target and an aluminum (Al) slice in a smaller area by an ion-beam sputtering deposition method. The sputtered films were postannealed at 450 °C. The x-ray photoelectron spectroscopy spectra were categorized by their oxygen bonding variations, which include high-binding-energy oxygen, (HBO), bridging oxygen, low-binding-energy oxygen, and shifts of the binding energies (BEs) of oxygen (O) and Ti signals. The enhancement of HBO and higher BE shifts of the O 1s spectra as a function of cosputtered Al in the film imply the formation of an Al-O-Ti linkage. Corresponding changes in the Ti 2p spectra further confirm the modification of properties of the cosputtered film that results from the variation of the chemical bonding environment. An observed correlation between the chemical structure and optical absorption of the Al cosputtered films can be used to modify the optical properties of the film.