Photoluminescence and compositional-structural properties of ion-beam sputter deposited Er-doped TiO_(2-x)N_x films: Their potential as a temperature sensor

摘要

Er-doped TiO_(2-x)N_x films were grown by Ar~+ ion-beam sputtering a Ti + Er target under different N_2 + O_2 high-purity atmospheres. The compositional-structural properties of the samples were investigated after thermal annealing the films up to 1000 ℃ under a flow of oxygen. Sample characterization included x-ray photoelectron spectroscopy, grazing incidence x-ray diffraction, Raman scattering, and photoluminescence experiments. According to the experimental data, both composition and atomic structure of the samples were very sensitive to the growth conditions and annealing temperature. In the as-deposited form, the N-rich TiO_(2-x)N_x films presented TiN crystallites and no photoluminescence. As the thermal treatments proceed, the films were transformed into TiO_2 and Er~(3+)-related light emission were observed in the visible and near-infrared ranges at room-temperature. Whereas the development of TiO_2 occurred due to the insertion-diffusion of oxygen in the films, light emission originated because of optical bandgap widening and/or structural-chemical variations in the vicinity of the Er~(3+) ions. Finally, the photoluminescence results in the visible range suggested the potential of the present samples in producing an optically based temperature sensor in the ～150-500 K range.