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Atomic Composition and Structural Properties of Blue Emitting BaAl 2 S 4 :Eu Electroluminescent Thin Films

2001; Institute of Physics; Volume: 40; Issue: 4R Linguagem: Inglês

10.1143/jjap.40.2451

1347-4065

Youji Inoue, Isao Tanaka, Katsu Tanaka, Yoshitaka Izumi, Shinji Okamoto, Mitsuhiro Kawanishi, Daisuke Barada, Noboru Miura, Hironaga Matsumoto, Ryotaro Nakano,

Ammonia Synthesis and Nitrogen Reduction

We have investigated the compositional and structural properties of blue emitting BaAl 2 S 4 :Eu electroluminescent thin films fabricated by switching electron-beam evaporation using two targets. The use of X-ray photoelectron spectroscopy (XPS) revealed that the ratio of barium to sulfur in thin films is 1.0:2.0, which is identical to the stoichiometry of BaAl 2 S 4 . The X-ray diffraction (XRD) peaks from the thin film were assigned to those of a BaAl 2 S 4 crystal. The photoluminescence (PL) spectrum shows emission from the 4f 6 5d→4f 7 transition of the activated Eu 2+ ions in BaAl 2 S 4 crystals. These results indicate that the crystalline phase in thin films is only BaAl 2 S 4 . The thin films also contain a large amount of oxygen impurities, which result in the formation of an Al 2 O 3 layer and amorphous barium aluminate.