A phosphor having a formula of T.sub.xE.sub.ySi.sub.zN.sub.rTb.sub.aL.sub.bM.sub.c is provided, in which T is Mg, Ca, Sr or Ba; E is Mg, Ca, Ba, Ti, Cu, Zn, B, Al, In, Sn, Sb, Bi, Ga, Y, La or Lu; L is Li, Na or K; M is Ce, Pr, Nd, Pm, Sm, Gd, Dy, Ho, Er, Tm, Yb or Mn; and 1.4x2.6, 0y0.5, 4.3z5.6, 7.4r9, 0.01a0.5, 0b0.5, 0c0.5, in which Tb ion is used as a luminescence center, and valence of the Tb ion is lower than 3+, and the phosphor is excited by an excitation light and has an emission band with a full width at half maximum greater than 50 nm. A method of forming the phosphor is also provided.

A phosphor having a formula of T.sub.xE.sub.ySi.sub.zN.sub.rTb.sub.aL.sub.bM.sub.c is provided, in which T is Mg, Ca, Sr or Ba; E is Mg, Ca, Ba, Ti, Cu, Zn, B, Al, In, Sn, Sb, Bi, Ga, Y, La or Lu; L is Li, Na or K; M is Ce, Pr, Nd, Pm, Sm, Gd, Dy, Ho, Er, Tm, Yb or Mn; and 1.4x2.6, 0y0.5, 4.3z5.6, 7.4r9, 0.01a0.5, 0b0.5, 0c0.5, in which Tb ion is used as a luminescence center, and valence of the Tb ion is lower than 3+, and the phosphor is excited by an excitation light and has an emission band with a full width at half maximum greater than 50 nm. A method of forming the phosphor is also provided.