Tunable performance of nanostructured Eu-doped oxide and oxynitride thin films

5th International Conference on "Smart and Multifunctional Materials, Structures and Systems", Perugia, Italy, June 5-9, 2016 ; Session D-3 - Phosphors, Quantum Dots and Low Dimensional Materials for Lighting and Displays ; http://2016.cimtec-congress.org/Rare earth (RE) doped materials are ideal candidates for the development of reliable emitters for integrated lighting devices. Silicon oxynitrides are compatible with the current silicon technology and show excellent optical properties including high transparency in the VIS-IR, and a tunable refractive index from that of SiO2 (1.45) to that of Si3N4 (2.01). Moreover, the inclusion of Al2O3 (1.67) to form SiAlON is advantageous providing further tuning of the optical properties and decreases the maximum phonon energy, which enhances RE-light emission efficiency. Some RE doped SiAlON have been studied as phosphors, however it have been seldom produced as thin films. We report the optical properties and emission performance of both a-Al2O3 and SiAlON thin films with nanostructured Eu doping. The Eu is distributed in the films forming well-defined doping layers with different interlayer spacing. It will be demonstrated that this nanometric distribution is essential to obtain either the 2+ or 3+ Eu oxidation state. Therefore, the film emission could be tuned from a broadband white emission characteristic from the superposition of the 5d levels to the 4f levels of the Eu2+, to a narrow and well-defined emission peaks characteristic of the 4f-4f transitions of the Eu3+.Peer Reviewe