Temperature dependence of structural and luminescence properties of Eu3+-doped Y2O3 red-emitting phosphor thin films by pulsed laser deposition

Pulse laser deposition was used to obtain nanocrystalline red-emitting Y2O3:Eu3+ thin-film phosphors. X-ray diffraction measurements show that the un-annealed thin film was amorphous, while those annealed were crystalline. At lower annealing temperature of 600-700 degrees C, cubic bixbyite Y2O3:Eu3+ was formed. As the annealing temperatures were increased to 800 degrees C, hexagonal phase emerged. The average crystallite size of the film was 64 nm. Photoluminescence measurement indicates intense red emission around 612 nm due to the D-5(0) -> F-7(2) transition. Scanning electron microscopy indicated that agglomerates of non-crystalline particles with spherical shapes were present for the un-annealed films. After annealing at high temperature, finer morphology was revealed. Atomic force microscopy further confirmed the formation of new morphology at the higher annealing temperatures. UV-Vis measurement indicated a band gap in the range of 4.6-4.8 eV. It was concluded that the annealing temperature played an important role in the luminescence intensity and crystallinity of these films.