Light emitting diode and method of fabricating the same
Exemplary embodiments of the present invention disclose a light emitting diode including an n-type contact layer doped with silicon, a p-type contact layer, an active region disposed between the n-type contact layer and the p-type contact layer, a superlattice layer disposed between the n-type contact layer and the active region, the superlattice layer including a plurality of layers, an undoped intermediate layer disposed between the superlattice layer and the n-type contact layer, and an electron reinforcing layer disposed between the undoped intermediate layer and the superlattice layer. Only a final layer of the superlattice layer closest to the active region is doped with silicon, and the silicon doping concentration of the final layer is higher than that of the n-type contact layer.
1. A light emitting diode, comprising:
an n-type contact layer;
a p-type contact layer disposed over the n-type contact layer;
an active region disposed between the n-type contact layer and the p-type contact layer and comprising a multi-quantum well structure including a quantum well layer;
a p-type clad layer disposed between the p-type contact layer and the active region;
a superlattice layer including a plurality of layers, disposed near the active region; and
a spacer layer disposed between the superlattice layer and the n-type contact layer and having a bandgap smaller than that of the barrier layer and greater than that of the quantum well layer.
2. The light emitting diode of claim 1 , further comprising an un-doped intermediate layer disposed between the n-type contact layer and the active region.
3. The light emitting diode of claim 1 , wherein the spacer layer comprises a stacked structure of at least two different InGaN layers.
4. The light emitting diode of claim 1 , wherein the at least one layer of the plurality of layers in the spacer layer positioned adjacent to the active region is doped with n-type impurities.
5. The light emitting diode of claim 1 , wherein:
the n-type contact layer includes n-type impurities; and
the at least one of the plurality of layers in the spacer layer that is doped with n-type impurities is doped with the n-type impurities at a higher concentration than a concentration of the n-type impurities in the n-type contact layer.
6. The light emitting diode of claim 1 , further comprising:
an intermediate layer disposed between the n-type contact layer and the spacer layer and including n-type impurities, wherein a concentration of the n-type impurities in the intermediate layer is higher than a concentration of n-type impurities in the n-type contact layer and lower than a concentration of n-type impurities in the spacer layer.
7. The light emitting diode of claim 6 , wherein the intermediate layer includes an n-AlGaN layer.
8. The light emitting diode of claim 7 , wherein the n-AlGaN layer in the intermediate layer has a gradually or stepwise reduced Al composition toward the active region than away from the active region.
9. The light emitting diode of claim 1 , wherein the p-type clad layer includes an AlGaN layer.
10. The light emitting diode of claim 9 , wherein Al composition of the AlGaN layer is gradually lowered toward the p-type contact layer.
11. The light emitting diode of claim 9 , further comprising an intermediate layer disposed between the n-type contact layer and the active region, wherein Al composition of the AlGaN layer is greater than that of the intermediate layer.
12. The light emitting diode of claim 1 , wherein the p-type clad layer includes a plurality of layers including at least one of AlGaN, GaN, or InGaN.
13. The light emitting diode of claim 1 , wherein the p-type clad layer includes a first layer and a second layer, the first layer is closer to the active region than the second layer is, and the first layer has a thickness smaller than the second layer.
14. A light emitting diode, comprising:
an n-type contact layer doped with n-type impurities;
a spacer layer disposed over the n-type contact layer and having a bandgap smaller than that of the barrier layer and greater than that of the quantum well layer;
an active region disposed over the spacer layer and having a multi-quantum well structure including a quantum well layer and a barrier layer;
a p-type contact layer disposed over the active region; and
a p-type clad layer disposed between the p-type contact layer and the active region.
15. The light emitting diode of claim 14 , wherein the quantum well layer includes an InGaN layer.
16. The light emitting diode of claim 14 , wherein the active region is not doped with the n-type impurities.
17. The light emitting diode of claim 14 , wherein the spacer layer includes a first semiconductor layer not doped with the n-type impurities and a second semiconductor layer doped with the n-type impurities.
18. The light emitting diode of claim 14 , wherein the spacer layer is doped with n-type impurities at higher concentration than a concentration of the n-type impurities in the n-type contact layer.
19. The light emitting diode of claim 14 , further comprising an intermediate layer formed between the n-type contact layer and the spacer layer and including n-AlGaN layer.
20. The light emitting diode of claim 19 , wherein the intermediate layer is doped with the n-type impurities at a concentration that is higher than a concentration of the n-type impurities in the n-type contact layer.
21. The light emitting diode of claim 19 , wherein the n-AlGaN layer has a gradually or stepwise reduced Al composition toward the active region than away from the active region.
22. The light emitting diode of claim 14 , wherein the n-type contact layer comprises at least two different n-type GaN layers and an n-type AlGaN layer disposed between the at least two different n-type GaN layers.
23. The light emitting diode of claim 14 , wherein the first and second semiconductor layers of the spacer layer include different InGaN layers.
24. The light emitting diode of claim 14 , wherein the p-type clad layer includes an AlGaN layer.
25. The light emitting diode of claim 24 , wherein Al composition of the AlGaN layer is gradually lowered toward the p-type contact layer.
26. The light emitting diode of claim 24 , further comprising an intermediate layer disposed between the n-type contact layer and the active region, wherein Al composition of the AlGaN layer is greater than that of the intermediate layer.
27. The light emitting diode of claim 14 , wherein the p-type clad layer includes a plurality of layers including at least one of AlGaN, GaN, or InGaN.
28. The light emitting diode of claim 14 , wherein the p-type clad layer includes a first layer and a second layer, the first layer is closer to the active region than the second layer is, and the first layer has a thickness smaller than the second layer.