Highly efficient and thermally stable blue-emitting AlN:Eu²⁺ phosphor for ultraviolet white light-emitting diodes

An Eu²⁺-activated AlN phosphor was synthesized by firing the powder mixture of AlN, R-Si₃N₄, and Eu₂O ₃at 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 Eu ²⁺ 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.