Lighting emitting device employing nanowire phosphors

1. A light emitting device, comprising:

a light emitting diode to emit light having a first wavelength with a main peak in at least one wavelength range selected from ultraviolet, blue and green wavelength ranges; and

nanowire phosphors to convert at least a portion of light having the first wavelength emitted from the light emitting diode into light with a second wavelength longer than the first wavelength,

wherein the nanowire phosphor is a nanowire comprising a nitride expressed by a general formula Al x In y Ga (1-x-y) N (0≦x<1, 0<y<1, 0<x+y≦1), and

wherein the Al x In y Ga (1-x-y) N nanowire phosphor has a composition ratio varying in a longitudinal direction such that the light having the second wavelength has at least two main peaks.

2. The light emitting device as claimed in claim 1 , wherein the nanowire phosphor is at least one nanowire selected from the group consisting of nanowires made of ZnO, ZnO doped with Ag, ZnO doped with at least one element selected from Al, Ga, In and Li, ZnO:Cu,Ga, ZnS:Cu,Ga, ZnS (1-x) Te x (0<x<1), CdS:Mn capped with ZnS, ZnSe, Zn 2 SiO 4 :Mn, and (Ba, Sr, Ca) 2 SiO 4 :Eu.

3. The light emitting device as claimed in claim 1 , further comprising a resin covering the light emitting diode,

wherein the nanowire phosphors are dispersed within the resin.

4. The light emitting device as claimed in claim 1 , wherein the nanowire phosphors are prepared by forming them on a substrate using an MOCVD, MOHVPE or MBE method and separating them from the substrate.

5. The light emitting device as claimed in claim 4 , wherein the substrate is a silicon substrate.

6. A light emitting device, comprising:

a light emitting diode to emit light having a first wavelength with a main peak in at least one wavelength range selected from ultraviolet, blue and green wavelength ranges; and

nanowire phosphors to convert at least a portion of light having the first wavelength emitted from the light emitting diode into light with a second wavelength longer than the first wavelength,

wherein the nanowire phosphor comprises a core nanowire and a nanoshell for covering the core nanowire, and

wherein the core nanowire comprises a nitride expressed by a general formula Al x In y Ga (1-x-y) N (0≦x<1, 0<y<1, 0<x+y≦1);

the nanoshell is made of a nitride expressed by a general formula Al x In y Ga (1-x-y) N (0≦x≦1, 0≦y<1, 0≦x+y≦1); and

the nitride forming the nanoshell has a bandgap larger than that of the nitride forming the core nanowire.

7. The light emitting device as claimed in claim 6 , wherein the core nanowire has a composition ratio varying in a longitudinal direction such that the light having the second wavelength has at least two main peaks.

8. The light emitting device as claimed in claim 6 , wherein the nanowire phosphor is at least one nanowire selected from the group consisting of nanowires made of ZnO, ZnO doped with Ag, ZnO doped with at least one element selected from Al, Ga, In and Li, ZnO:Cu,Ga, ZnS:Cu,Ga, ZnS (1-x) Te x (0<x<1), CdS:Mn capped with ZnS, ZnSe, Zn 2 SiO 4 :Mn, and (Ba, Sr, Ca) 2 SiO 4 :Eu.

9. The light emitting device as claimed in claim 6 , further comprising a resin covering the light emitting diode,

wherein the nanowire phosphors are dispersed within the resin.

10. The light emitting device as claimed in claim 6 , wherein the nanowire phosphors are prepared by forming them on a substrate using an MOCVD, MOHVPE or MBE method and separating them from the substrate.

11. The light emitting device as claimed in claim 10 , wherein the substrate is a silicon substrate.