Blue-violet phosphate phosphor thin films for EL

Photoluminescence (PL) and electroluminescence (EL) in blue-violet emission were observed in newly developed phosphate phosphor thin films such as Ba3(PO4)2:Eu and Ba3(PO4)2:Ti. These phosphate phosphor thin films were first deposited on thick BaTiO3 ceramic sheets by r.f. magnetron sputtering using powder targets and then post-annealed in various atmospheres. Blue-violet PL and EL emissions were obtained in Ba3(PO4)2:Eu and Ba3(PO4)2:Ti phosphor thin films that were deposited in an Ar + H2 (10%) gas atmosphere and then post-annealed above about 900 °C in an Ar + H2 (10%) gas atmosphere. In particular, the EL observed in Ba3(PO4)2:Eu thin films exhibited two peaks, a red emission peaking at about 615 nm and a blue-violet emission peaking at about 420 nm. A luminance of 2.0 cd/m2 in blue-violet emission was obtained in a thin-film EL device using a two step post-annealed Ba3(PO4)2:Eu thin-film emitting layer: step 1, post-annealing at 1000 °C in air for 1 h, and step 2, post-annealing at 1000 °C in an Ar + H2 atmosphere.