Highly Efficient and Thermally Stable Blue-Emitting AlN:Eu2+ Phosphor for Ultraviolet White Light-Emitting Diodes

Abstract

An Eu2+-activated AlN phosphor was synthesized by firing the powder mixture of AlN, α-Si3N4, and Eu2O3 at 1500−2050 °C for 4 h under 1.0 MPa N2. The phase purity, photoluminescent properties, thermal quenching, and quantum efficiency of the fired samples were investigated. A single AlN wurtzite phase was formed at low doping concentrations of Eu2+ (≤0.1 mol %) and Si (≤2.2 mol %). The introduction of Si is essential for the solubility of Eu2+ in the AlN lattice. Intense blue luminescence with a peak emission wavelength of 465 nm was observed in AlN:Eu2+, when Si was doped simultaneously. This blue phosphor shows a small thermal quenching, retaining the luminance of 90% at 150 °C. The absorption and external quantum efficiencies of AlN:Eu2+ are 63%μ and 46% upon 365 nm excitation, respectively. These results indicate that AlN:Eu2+ has great potential as a blue phosphor for white light-emitting diodes (LEDs) utilizing UV chips as the light source.