Light emitting diode having strain-enhanced well layer

1. A light emitting diode, comprising:

an n-contact layer;

a p-contact layer;

an active layer comprising a barrier layer and a well layer, the active layer being arranged between the n-contact layer and the p-contact layer; and

a strain-enhancing layer comprising the barrier layer and InAlGaN-based quantum dots disposed in the barrier layer, the strain-enhancing layer configured to increase a strain applied to the well layer.

2. The light emitting diode of claim 1 , wherein the barrier layer and the well layer each comprise a GaN based compound semiconductor.

3. The light emitting diode of claim 2 , wherein the strain-enhancing layer is arranged between the barrier layer and the well layer or between the n-contact layer and the barrier layer, and

wherein the strain-enhancing layer comprises a GaN based compound semiconductor configured to provide a higher compressive strain to the well layer than a compressive strain to the well layer from the barrier layer alone.

4. The light emitting diode of claim 3 , wherein the barrier layer comprises a GaN layer, the well layer comprises an InGaN layer, and the strain-enhancing layer comprises InAlGaN.

5. The light emitting diode of claim 3 , wherein the strain-enhancing layer comprises a super lattice structure.

6. The light emitting diode of claim 2 , further comprising:

an electron injection layer arranged between the strain-enhancing layer and the active layer,

wherein the strain-enhancing layer is arranged between the n-contact layer and the active layer.

7. The light emitting diode of claim 6 , wherein the strain-enhancing layer comprises AlGaN, and the electron injection layer comprises n-GaN.

8. The light emitting diode of claim 1 , wherein the quantum dots comprise a lattice constant less than that of the barrier layer.

9. The light emitting diode of claim 1 , further comprising a substrate disposed below the n-type contact layer,

wherein the strain-enhancing layer is arranged between the active layer and the substrate, and the strain-enhancing layer comprises a GaN based semiconductor layer comprising a pattern.

10. The light emitting diode of claim 9 , wherein the pattern is integrally formed in the n-contact layer.

11. A light emitting diode, comprising:

a first-type contact layer;

a second-type contact layer;

an active layer comprising a barrier layer and a well layer, the active layer being arranged between the first-type contact layer and the second-type contact layer; and

a strain-enhancing layer disposed between the barrier layer and the well layer, and configured to increase a compressive strain applied to the well layer, the strain-enhancing layer comprising a lattice constant lower than a lattice constant of the barrier layer.

12. The light emitting diode of claim 11 , wherein the strain-enhancing layer comprises InAlGaN, the barrier layer comprises GaN, and the well layer comprises InGaN.

13. The light emitting diode of claim 11 , wherein the strain-enhancing layer comprises a super lattice structure.

14. The light emitting diode of claim 13 , wherein the strain-enhancing layer comprises InAlGaN/InAlGaN and the barrier layer comprises GaN.

15. The light emitting diode of claim 11 , wherein the strain-enhancing layer comprises quantum dots.

16. The light emitting diode of claim 11 , wherein the barrier layer comprises quantum dots.

17. The light emitting diode of claim 11 , wherein the strain-enhancing layer comprises a patterned n-GaN layer.

18. The light emitting diode of claim 17 , wherein the patterned n-GaN layer comprises dislocation regions and crystalline regions.

19. A light emitting diode, comprising:

a first-type contact layer;

a second-type contact layer;

an active layer comprising a barrier layer and a well layer, the active layer being disposed between the first-type contact layer and the second-type contact layer; and

a strain-enhancing layer disposed in the barrier layer and comprising quantum dots, the strain-enhancing layer configured to increase a compressive strain applied to the well layer and comprising a lattice constant lower than a lattice constant of the barrier layer.