Deposition of ultrathin rare-earth doped Y2O3 phosphor films on alumina nanoparticles

Ultrathin films of Eu3+ doped Y2O3 were deposited onto alumina nanoparticles using a unique solution synthesis method. The surface structure, composition, and morphology of the thin films deposited were analysed using high resolution transmission electron microscopy (TEM) and high angle annular dark field scanning TEM imaging and energy dispersive x-ray measurements. The films deposited were extremely thin, on the order of 3–5 nm, and uniformly covered all the alumina nanoparticles. X-ray diffraction was used to investigate the phases and structures of the thin films deposited. At the heat treatment temperature of 600 ◦C, cubic Y2O3 nanocrystals were found in the film while as-coated layers exhibited mainly amorphous features. As the heat treatment temperature increased to 750 ◦C, the amorphous thin film became well crystallized. Optical properties of Eu3+ doped Y2O3 films were characterized by fluorescence spectroscopy. Strong photoluminescence was observed in the sample annealed at 750 ◦C, from the fluorescence of Eu3+ ions in a well-crystallized film, consistent with the x-ray diffraction and TEM observations.