Patent ID: 8551360

Claim:
A method of manufacturing a rare-earth doped alkaline-earth silicon nitride phosphor, said method comprising the steps of: selecting one or more compounds each comprising the groups consisting of the rare-earths elements, the alkaline-earth elements, silicon and nitrogen wherein together the selections comprise necessary elements to form a rare-earth doped alkaline-earth silicon nitride phosphor; bringing the one or more compounds to an elevated temperature in between 1,200 and 1,700 degrees Celsius in reaction for forming the rare-earth doped alkaline-earth silicon nitride phosphor, wherein an amount of oxygen is being incorporated in the rare-earth doped alkaline-earth silicon nitride phosphor thus formed; partly substituting nitrogen anions of the alkaline-earth silicon nitride phosphor for carbon by which vacancies are created, filled or annihilated within the lattice of the phosphor resulting in the formation of a modified alkaline-earth silicon nitride phosphor having a stoichiometric composition so as to at least partly prevent the creation of defects by formation of a non-stoichiometric oxygen-containing alkaline-earth silicon nitride phosphor, wherein the resulting rare-earth doped alkaline-earth silicon nitride phosphor is characterized by a general formula of: AE 2 Si 5 N 8-2x C x O x :RE wherein AE is an alkaline-earth element; RE is a rare earth element; and wherein x is smaller than 1; determining a suitable amount of carbon to substitute by determining an oxygen content in the starting material or the amount of oxygen introduced during the reaction; and incorporating the suitable amount of carbon in the phosphor to prevent defect creation.