Blue-Emitting Eu²⁺-Doped CaAl₂O₄ Phosphor Thin Films Prepared Using Pulsed Laser Deposition Technique with Post Annealing

Abstract

Blue-emitting Eu 2+ -doped calcium aluminate phosphor thin films were obtained using the pulsed laser deposition technique with post annealing. As-deposited films were amorphous and showed weak red Eu 3+ photoluminescence (PL). By annealing in reducing atmosphere (N 2 /H 2 :2% mixed gas) at 950°C for 3 h, the film was crystallized and showed a PL emission band peaking at about 447 nm, which originated from the 4f 6 5d to 4f 7 transition of Eu 2+ ion. It is considered that the deposited film consists mainly of CaAl 2 O 4 and partly of other binary compounds of the CaO–Al 2 O 3 system. It was determined that the PL intensity of Eu 2+ in CaAl 2 O 4 can be controlled by the laser fluence, target-substrate distance and injection gas.