(Invited) Enhancing the Blue Emission in Ce Doped Silicon Oxynitrides Thin Films for Electroluminescence Device Applications

Ce-doped SiOxNy and SiAlON matrices are promising materials for blue LED applications. The uniqueness of this approach stems from the fact that SiOxNy, as a host, combines specific properties of individual SiOx and SiNy matrices like solubility, efficient emission, 5 eV gap etc. with a broad excitation range (400 to 500 nm) of Ce3+ due to the 4f-5d transitions. Furthermore, the co-doping with aluminum enhances the Ce3+ emission. In this work, we fabricated electroluminescent devices using SiOxNy: Ce3+ and SiAlON: Ce3+ as an active layers and studied the resulting emission under optical and electrical excitation as a function of nitrogen, cerium and aluminum concentrations. I-V measurements were conducted to determine the SiOxNy: Ce3+ layer electrical parameters. The transport through the devices obeys a Poole-Frenkel conduction mechanism. It was demonstrated that by optimizing the SiOxNy:Ce3+ material growth parameters an improvement of electroluminescence yield can be achieved with maximum intensity achieved for devices with Ce content of 4 at.%.