Epitaxial gallium nitride based light emitting diode and method of making thereof

1. A light emitting diode (LED), comprising:

a n-doped region;

a p-doped region; and

a light emitting region located between the n-doped region and a p-doped region, wherein the n-doped region comprises a first GaN layer, at least one n-doped second GaN layer located over the first GaN layer, an AlGaN dislocation blocking layer located over the at least one n-doped second GaN layer, and a n-doped third GaN layer located over the AlGaN dislocation blocking film;

wherein the light emitting region comprises:

an epitaxial first strain-modulating film located on the n-type region;

an epitaxial first cap layer located on the first strain-modulating film;

an epitaxial second strain-modulating film located on the first cap layer;

an epitaxial second cap layer located on the second strain-modulating film;

an epitaxial third strain-modulating film located on the second cap layer;

an epitaxial intermediate cap located on the third strain-modulating film;

a first quantum well set located on the intermediate cap;

an epitaxial AlGaN containing cap region located on the first quantum well set;

a second quantum well set located on the AlGaN containing cap region; and

an epitaxial third cap layer located on the second quantum well set.

2. The LED of claim 1 , wherein:

the first strain-modulating film contains InGaN; and

the second strain-modulating film comprises containing InGaN having a higher indium content than the first strain-modulating film.

3. The LED of claim 2 , wherein:

the first strain-modulating film comprises an InGaN bulk layer or a InGaN/GaN superlattice in which InGaN contains 1-5 atomic percent indium;

the second strain-modulating film comprises an InGaN bulk layer or an InGaN/GaN superlattice in which InGaN contains 5-12 atomic percent indium; and

the first cap layer, the second cap layer and the third cap layer are selected from one or more of an AlGaN layer, a GaN layer, an InGaN layer, an AlGaN/GaN superlattice, a GaN/AlGaN superlattice, a graded composition AlGaN layer in which the composition continuously varies from Al x Ga 1-x N to Al y Ga 1-y N, where x and y do not equal each other, or stepped AlGaN sublayers comprising Al x Ga 1-x N/Al y Ga 1-y N/Al z Ga 1-z N sublayers, where x, y and z do not equal each other.

4. The LED of claim 3 , wherein the third strain-modulating film comprises a bulk InGaN layer or an InGaN/GaN superlattice in which InGaN contains 13-18 atomic percent indium.

5. The LED of claim 4 , wherein the intermediate cap comprises a heavily silicon doped GaN layer.