Light emitting device having zener diode therein and method of fabricating the same

1. A light emitting device, comprising:

a P-type silicon substrate having a zener diode region and a light emitting diode region;

a first N-type compound semiconductor layer contacted to the zener diode region of the P-type silicon substrate to exhibit characteristics of a zener diode together with the P-type silicon substrate;

a second N-type compound semiconductor layer positioned on the light emitting diode region of the P-type silicon substrate and spaced apart from the first N-type compound semiconductor layer;

a P-type compound semiconductor layer positioned on the second N-type compound semiconductor layer; and

an active layer interposed between the second N-type compound semiconductor layer and the P-type compound semiconductor layer.

2. The light emitting device as claimed in claim 1 , wherein the silicon substrate is a porous silicon substrate.

3. The light emitting device as claimed in claim 2 , wherein the porous silicon substrate is a substrate formed by anodizing a silicon substrate.

4. The light emitting device as claimed in claim 2 , wherein the first and second N-type compound semiconductor layers are formed from an identical N-type compound semiconductor layer grown on the P-type silicon substrate.

5. The light emitting device as claimed in claim 2 , wherein the P-type compound semiconductor layer is positioned on one region of the second N-type compound semiconductor layer, and the other region thereof is exposed.

6. The light emitting device as claimed in claim 2 , further comprising a transparent electrode layer positioned on the P-type compound semiconductor layer.

7. The light emitting device as claimed in claim 1 , wherein the first and second N-type compound semiconductor layers are formed from an identical N-type compound semiconductor layer grown on the P-type silicon substrate.

8. The light emitting device as claimed in claim 1 , wherein the P-type compound semiconductor layer is positioned on one region of the second N-type compound semiconductor layer, and the other region thereof is exposed.

9. The light emitting device as claimed in claim 1 , further comprising a transparent electrode layer positioned on the P-type compound semiconductor layer.

10. The light emitting device as claimed in claim 9 , wherein the transparent electrode layer is formed of indium tin oxide (ITO) or Ni/Au.

11. The light emitting device as claimed in claim 9 , wherein the transparent electrode layer is formed of ZnO.

12. The light emitting device as claimed in claim 11 , wherein the ZnO transparent electrode layer has side surfaces inclined at a predetermined angle with respect to a surface perpendicular to the P-type compound semiconductor layer.

13. The light emitting device as claimed in claim 9 , further comprising electrode pads respectively formed on the first and second N-type compound semiconductor layers and the transparent electrode layer.

14. A method of fabricating a light emitting device, comprising:

growing an N-type compound semiconductor layer, an active layer and a P-type compound semiconductor layer on a P-type silicon substrate having a zener diode region and a light emitting diode region; and

patterning the P-type compound semiconductor layer, the active layer and the N-type compound semiconductor layer using photolithographic and etching processes to form a first N-type compound semiconductor layer of which a top surface is exposed on the zener diode region and to form a light emitting diode on the light emitting diode region,

wherein the P-type silicon substrate and the first N-type compound semiconductor layer have characteristics of a zener diode, and the light emitting diode includes a second N-type compound semiconductor layer spaced apart from the first N-type compound semiconductor layer, a P-type compound semiconductor layer positioned on the second N-type compound semiconductor layer, and an active layer interposed between the P-type compound semiconductor layer and the second N-type compound semiconductor layer.

15. The method as claimed in claim 14 , wherein the silicon substrate is a porous silicon substrate.

16. The method as claimed in claim 15 , further comprising:

forming a transparent electrode layer defined on the light emitting diode.

17. The method as claimed in claim 14 , further comprising:

forming a transparent electrode layer defined on the light emitting diode.

18. The method as claimed in claim 17 , wherein forming the transparent electrode layer defined on the light emitting diode comprises:

forming a transparent electrode layer on the P-type compound semiconductor layer before patterning the P-type compound semiconductor layer, the active layer and the N-type compound semiconductor layer; and

patterning the transparent electrode layer formed on the P-type compound semiconductor layer to be defined in the light emitting diode region.

19. The method as claimed in claim 18 , wherein the transparent electrode layer is formed of ZnO.

20. The method as claimed in claim 19 , wherein the ZnO transparent electrode layer is patterned to have side surfaces inclined at a predetermined angle with respect to a surface perpendicular to the P-type compound semiconductor layer of the light emitting diode.