Ac light emitting device having photonic crystal structure and method of fabricating the same
View Patent ↗Disclosed is an AC light emitting device having photonic crystal structures and a method of fabricating the same. The light emitting device includes a plurality of light emitting cells and metallic wirings electrically connecting the light emitting cells with one another. Further, each of the light emitting cells includes a first conductive type semiconductor layer, a second conductive type semiconductor layer disposed on one region of the first conductive type semiconductor layer, and an active layer interposed between the first and second conductive type semiconductor layers. In addition, a photonic crystal structure is formed in the second conductive type semiconductor layer. The photonic crystal structure prevents light emitted from the active layer from laterally propagating by means of a periodic array, such that light extraction efficiency of the light emitting device can be improved. Furthermore, the metallic wirings electrically connect a plurality of light emitting cells with one another such that an AC light emitting device can be provided.
1. An alternating current (AC) light emitting device, comprising:
a plurality of light emitting cells each comprising a first conductive type semiconductor layer, a second conductive type semiconductor layer disposed on one region of the first conductive type semiconductor layer, an active layer interposed between the first and second conductive type semiconductor layers, and a photonic crystal structure formed only in the second conductive type semiconductor layer;
transparent electrodes respectively disposed on the second conductive type semiconductor layers; and
metallic wirings electrically connecting the plurality of light emitting cells with one another,
wherein each of the plurality of light emitting cells is configured to emit light generated in the respective active layer through the photonic crystal structure and the transparent electrode.
2. The device of claim 1 , wherein the photonic crystal structure comprises a lattice of holes two dimensionally arranged.
3. The device of claim 2 , wherein the holes are filled with an insulating material comprising a different refractive index from the second conductive type semiconductor layer.
4. The device of claim 2 , wherein the holes are filled with air.
5. The device of claim 1 , wherein the photonic crystal structure comprises a periodic unevenness formed in the second conductive type semiconductor layer.
6. The device of claim 1 , wherein the photonic crystal structure comprises a lattice of second conductive type semiconductor rods.
7. The device of claim 6 , wherein a space between the rods is filled with an insulating material comprising a different refractive index from the second conductive type semiconductor layer.
8. The device of claim 6 , wherein the holes are filled with air.
9. The device of claim 1 , further comprising first electrode pads formed on other regions of the first conductive type semiconductor layers and second electrode pads formed on the transparent electrodes, wherein each of the metallic wirings connects the first and second electrode pads of the adjacent light emitting cells.
10. An alternating current (AC) light emitting device, comprising:
a plurality of light emitting cells each comprising a first conductive type semiconductor layer, a second conductive type semiconductor layer disposed on one region of the first conductive type semiconductor layer, an active layer interposed between the first and second conductive type semiconductor layers, and a photonic crystal structure formed in the second conductive type semiconductor layer but not in either the first conductive type semiconductor layer or the active layer;
transparent electrodes respectively disposed on the second conductive type semiconductor layers; and
metallic wirings electrically connecting the plurality of light emitting cells with one another,
wherein each of the plurality of light emitting cells is configured to emit light generated in the respective active layer through the photonic crystal structure and the transparent electrode.
11. The device of claim 10 , wherein the photonic crystal structure comprises a lattice of holes two dimensionally arranged.
12. The device of claim 11 , wherein the holes are filled with an insulating material comprising a different refractive index from the second conductive type semiconductor layer.
13. The device of claim 11 , wherein the holes are filled with air.
14. The device of claim 10 , wherein the photonic crystal structure comprises a periodic unevenness formed in the second conductive type semiconductor layer.
15. The device of claim 10 , wherein the photonic crystal structure comprises a lattice of second conductive type semiconductor rods.
16. The device of claim 15 , wherein a space between the rods is filled with an insulating material comprising a different refractive index from the second conductive type semiconductor layer.
17. The device of claim 15 , wherein the holes are filled with air.
18. The device of claim 10 , further comprising first electrode pads formed on other regions of the first conductive type semiconductor layers and second electrode pads formed on the transparent electrodes, wherein each of the metallic wirings connects the first and second electrode pads of the adjacent light emitting cells.