Red light-emitting fluorescent substance and light-emitting device employing the same

1. A light-emitting device comprising:

a light-emitting element to emit light, and

a fluorescent substance (R) giving off luminescence under excitation by light of said light emitting element, wherein the fluorescent substance R is represented by the following formula (1):

(M 1-x EC x ) a M 1 b AlO c N d   (1)

in which

M is an element selected from the group consisting of IA group elements, IIA group elements, IIIA group elements, IIIB group elements, rare earth elements and IVA group elements;

EC is an element selected from the group consisting of Eu, Ce, Mn, Tb, Yb, Dy, Sm, Tm, Pr, Nd, Pm, Ho, Er, Cr, Sn, Cu, Zn, As, Ag, Cd, Sb, Au, Hg, Tl, Pb, Bi and Fe;

M 1 is different from M and is selected from the group consisting of tetravalent elements; and

x, a, b, c and d are numbers satisfying the conditions of

0<x<0.2,

0.63<a<0.80,

2.1<b<2.63,

0≦c≦0.24 and

4≦d≦5, respectively; and

emitting luminescence having a peak in the wavelength range of 620 to 670 nm under excitation by light in the wavelength range of 250 to 500 nm.

2. The device according to claim 1 , wherein

said light-emitting element emits light in the wavelength range of 250 to 500 nm, and

further comprising another fluorescent substance (Y) that gives off luminescence having a peak in the wavelength range of 540 to 580 nm under excitation by light of said light-emitting element.

3. The device according to claim 2 , wherein said fluorescent substance (Y) is selected from the group consisting of YAG phosphor, (Sr,Ca,Ba,Eu) 2 SiO 4 , (Sr,Ca,Ba,Eu) 3 SiO 5 , (CaEu)Ga 2 S 4 , and α-SiAlon phosphor.

4. The device according to claim 1 , wherein

said light-emitting element emits light in the wavelength range of 250 to 430 nm,

further comprising another fluorescent substance (Y) that gives off luminescence having a peak in the wavelength range of 540 to 580 nm under excitation by light of said light-emitting element, and

still another fluorescent substance (B) gives off luminescence having a peak in the wavelength range of 400 to 490 nm under excitation by light of said light-emitting element.

5. The device according to claim 4 , wherein said fluorescent substance (Y) is selected from the group consisting of YAG phosphor, (Sr,Ca,Ba,Eu) 2 SiO 4 , (Sr,Ca,Ba,Eu) 3 SiO 5 , (CaEu)Ga 2 S 4 , and α-SiAlon phosphor.

6. The device according to claim 4 , wherein said fluorescent substance (B) is selected from the group consisting of (Ba,Eu)MgAl 10 O 17 , (Sr,Ca,Ba,Eu) 10 (PO 4 ) 5 Cl 2 and (Sr,Eu)Si 9 Al 19 ON 31 .

7. The device according to claim 1 , wherein

said light-emitting element emits light in the wavelength range of 250 to 500 nm, and

further comprising another fluorescent substance (G) that gives off luminescence having a peak in the wavelength range of 490 to 540 nm under excitation by light of said light-emitting element.

8. The device according to claim 1 , wherein

said light-emitting element emits light in the wavelength range of 250 to 430 nm,

further comprising another fluorescent substance (G) that gives off luminescence having a peak in the wavelength range of 490 to 540 nm under excitation by light of said light-emitting element, and

still another fluorescent substance (B) that gives off luminescence having a peak in the wavelength range of 400 to 490 nm under excitation by light of said light-emitting element.

9. The device according to claim 8 , wherein said fluorescent substance (B) is selected from the group consisting of (Ba,Eu)MgAl 10 O 17 , (Sr,Ca,Ba,Eu) 10 (PO 4 ) 5 Cl 2 and (Sr,Eu)Si 9 Al 19 ON 31 .

10. A light-emitting device module comprising a plural number of the devices according to claim 1 and a substrate on which said plural devices are placed.

11. The module according to claim 10 , satisfying the condition of 1≦(d/a)≦5 in which a is the longitudinal length of each of said devices and d is the shortest interval between neighboring two of said devices.

12. The device according to claim 1 , wherein said M 1 in the formula (1) is Si.

13. The device according to claim 1 , wherein said M in the formula (1) is an element selected from the group consisting of Li, Na, K, Mg, Ca, Sr, Ba, B, In, Ga, Y, Sc, Gd, La, Lu and Ge.

14. The device according to claim 1 , wherein said b in the formula (1) is a number satisfying the condition of 2.1<b<2.5.

15. The device according to claim 1 , wherein said c in the formula (1) is a number satisfying the condition of 0.05<c≦0.21.