Patent ID: 7589358

Claim:
A phosphor substrate, comprising a nitride containing at least one element selected from Group XIII (IUPAC 1989) having: a general formula XN, wherein X is at least one element selected from B, Al, Ga and In, a general formula XN:Y, wherein X is at least one element selected from B, Al, Ga and In, and Y is at least one element selected from Be, Mg, Ca, Sr, Ba, Zn, Cd and Hg, or a general formula XN:Y,Z, wherein X is at least one element selected from B, Al, Ga and In, Y is at least one element selected from Be, Mg, Ca, Sr, Ba, Zn, Cd and Hg, and Z is at least one element selected from C, Si, Ge, Sn, Pb, O and S; and wherein said phosphor substrate contains alkali metals at a concentration of 0.1 ppm or more.