저널

NaNbO3:Eu 3+ phosphor thin films were grown on quartz substrates by radio-frequency magnetron sputtering at a growth temperature of 100 oC, with subsequent annealing at temperatures of 800, 900, and 1000 oC. The effects of annealing temperature on the structural, morphological, and optical properties of the thin films were investigated. The NaNbO3:Eu 3+ sputtering target was synthesized by a solid-state reaction of raw materials Na2CO3, Nb2O5, and Eu2O3. The X-ray diffraction patterns exhibited that the thin films had two mixed phases of NaNbO3 and Eu2O3. Surface morphologies were investigated by using field emission-scanning electron microscopy and indicated that the grains of the thin film annealed at 1000 oC showed irregular shapes with an average size of approximately 300 nm. The excitation spectra of Eu 3+ -doped NaNbO3 thin film consisted of a strong charge transfer band centered at 304 nm in the range of 240–350 nm and two weak peaks at 395 and 462 nm, respectively, resulting from the 7 F0→5 L6 and 7 F0→5H2 transitions of Eu 3+ ions. The emission spectra under excitation at 304 nm exhibited an intense red band centered at 614 nm and two weak bands at 592 and 681 nm. As the annealing temperature increased from 800 oC to 1000 oC, the intensities of all the emission bands and the band gap energies gradually increased. These results indicate that the higher annealing temperature enhance the luminescent properties of NaNbO3:Eu 3+ thin films.

Thin Film, Photoluminescence, Annealing