| 摘要 |
PROBLEM TO BE SOLVED: To provide a light-emitting device having an enough lifetime, by inhibiting deterioration of a fluorescent substance. SOLUTION: This light-emitting device has the fluorescent substance 21 of which the surface is covered with a covering material 22 having quality different from that of the fluorescent material by a chemical vapor-phase reaction process, wherein any one of a metal oxide, a metal nitride, and a metal oxynitride is used as the covering material. The covering material is formed so that the surface of the fluorescent substance is coated with the covering material in an approximately smooth filmy state or the whole surface of the fluorescent substance is covered with aggregated particles of the covering material which are given by aggregating many fine particles considerably smaller than the fluorescent substance. One or more elements of Al, Si, and rare earth elements are used as metal elements for composing the covering material. Further, a water-soluble fluorescent substance having translucensy, an alkaline-earth silicon nitride fluorescent substance, an alkaline-earth silicon oxynitride fluorescent substance, etc., is used as the fluorescent material. A BET value of the covered fluorescent material is 1.0 to 10 times the BET value which is measured before the fluorescent material is covered, and an average thickness of the cover is 10 to 500 nm. COPYRIGHT: (C)2005,JPO&NCIPI
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