Near-infrared luminescence of Tm3+-doped CeO2 films based on silicon substrates

CeO2/Tm2O3 multilayer films were deposited on silicon substrates by electron-beam evaporation. Tm3+ ions were doped in CeO2 after the films were annealed in oxygen atmosphere at 1000 °C. The doping concentration of Tm3+ varies in the range of 0.1–3 mol%. A series of near-infrared emission peaks were observed under the excitation of 330 nm, which correspond to 1G4–3H5, 3H4–3H6, 1G4–3H4, 3H5–3H6, 3F2–3H5, 3H4–3F4, 1G4–3F3,2 and 3F4–3H6 transitions of Tm3+, respectively. The dominant transition of 3H4–3H6 near 805 nm was within optical transmission window. The luminescence properties and the crystal structure of CeO2:Tm3+ films were investigated by excitation and emission spectroscopy and X-ray diffraction. Meanwhile, the substitution process of Ce4+ by Tm3+ was illustrated, and lattice expansion of the matrix CeO2 gave rise to the increase in FWHM of CeO2 diffraction peaks. In addition, the effect of Tm3+ concentration on photoluminescence was also studied, and the optimal concentration of Tm3+ was 0.5 mol%.