Light emitting diode with light emitting layer containing nitrogen and phosphorus
View Patent ↗Embodiments of the invention include an n-type region, a p-type region, and a light emitting layer disposed between the n-type region and the p-type region. The light emitting layer is a III-V material comprising nitrogen and phosphorus. The device also includes a graded region disposed between the light emitting layer and one of the p-type region and the n-type region. The composition of materials in the graded region is graded.
1. A device comprising:
an n-type region;
a p-type region;
a light emitting layer, wherein the light emitting layer is disposed between the n-type region and the p-type region, wherein the light emitting layer is a III-V material comprising nitrogen and phosphorus;
a first graded region disposed between the light emitting layer and the p-type region, wherein a composition in the first graded region is graded; and
a second graded region disposed between the light emitting layer and the n-type region, wherein a composition in the second graded region is graded.
2. The device of claim 1 wherein the light emitting layer is InGaN x P 1-x , wherein 0<X≦0.03.
3. The device of claim 1 wherein the light emitting layer has a composition that when forward biased emits light having a peak wavelength in a range of green to red.
4. The device of claim 1 wherein the composition in the first graded region is graded from GaP in a portion of the first graded region closest to the p-type region to AlGaP in a portion of the first graded region closest to the light emitting layer.
5. The device of claim 1 wherein the composition in the second graded region is graded from a composition of GaP in a portion of the second graded region closest to the n-type region to a composition of AlGaP in a portion of the second graded region closest to the light emitting layer.
6. The device of claim 1 wherein the n-type region and the p-type region are GaP.
7. The device of claim 1 wherein the n-type region, light emitting layer, and first and second graded regions are grown over a p-type GaP substrate.
8. A device comprising:
an n-type region;
a p-type region;
a light emitting layer, wherein the light emitting layer is disposed between the n-type region and the p-type region, wherein the light emitting layer is a III-V material comprising nitrogen and phosphorus; and
a graded region disposed between the light emitting layer and one of the p-type region and the n-type region, wherein a composition in the graded region is graded;
wherein the graded region comprises a portion of constant composition disposed between two portions of graded composition.
9. A device comprising:
an n-type region;
a p-type region;
a light emitting layer, wherein the light emitting layer is disposed between the n-type region and the p-type region, wherein the light emitting layer is a III-V material comprising nitrogen and phosphorus; and
a graded region disposed between the light emitting layer and one of the p-type region and the n-type region, wherein a composition in the graded region is graded;
wherein:
the graded region is disposed between the p-type region and the light emitting layer;
the graded region comprises:
a first portion of constant composition disposed in direct contact with the light emitting layer; and
a second portion of graded composition disposed in direct contact with the p-type region; and
the second portion is AlGaP and a composition of aluminum is graded.
10. The device of claim 9 wherein the light emitting layer is between 2 nm and 10 nm thick.
11. The device of claim 1 wherein:
the first graded region is Al x Ga 1-x P, wherein x is graded from 0 to 1; and
the second graded region is Al x Ga 1-x P, wherein x is graded from 1 to 0.
12. The device of claim 11 wherein the light emitting layer is between 10 nm and 100 nm thick.
13. The device of claim 1 wherein:
the first graded region is Al x Ga 1-x P;
0≦x≦1; and
the composition of Al is graded.
14. A method comprising:
growing a light emitting layer disposed between an n-type region and a p-type region, wherein the light emitting layer is a III-V material comprising nitrogen and phosphorus; and
growing a graded region disposed between the light emitting layer and one of the p-type region and the n-type region, wherein a composition in the graded region is graded;
wherein the graded region comprises a portion of constant composition disposed between two portions of graded composition.
15. The method of claim 14 wherein growing a graded region comprises varying a growth temperature to vary a composition in the graded region.
16. The method of claim 14 wherein growing a graded region comprises varying flow rates of precursor materials.
17. The method of claim 14 wherein growing a graded region comprises varying relative flow rates of different precursor materials.