LIGHT EMITTING DEVICE, PHOSPHOR AND METHOD FOR PREPARING PHOSPHOR

摘要

A light emitting device which comprises a phosphor having a surface being coated with a coating material different form the phosphor preferably through the chemical vapor deposition method, wherein the coating material is a metal oxide, a metal nitride or a metal oxynitride, and preferably wherein the coating material is applied on the surface in an almost flat and smooth manner, or in a manner such that numbers of fine particles thereof having a size considerably smaller than that of the phosphor are coagulated and covers the whole of the surface, and preferably wherein the coating material comprises at least one of metal elements consisting of Al, Si and rare earth elements, and preferably wherein the phosphor has light transmitting property and solubility in water and is an alkaline earth silicon nitride phosphor, an alkaline earth silicon oxynitride phosphor or the like, and preferably wherein the coated phosphor has a BET value 1.0 to 10 times that of the phosphor before coating, and preferably wherein the phosphor is coated in an average thickness of 10 nm to 500 nm.