P-type doping layers for use with light emitting devices
View Patent ↗A light emitting diode (LED) comprises an n-type Group III-V semiconductor layer, an active layer adjacent to the n-type Group III-V semiconductor layer, and a p-type Group III-V semiconductor layer adjacent to the active layer. The active layer includes one or more V-pits. A portion of the p-type Group III-V semiconductor layer is in the V-pits. A p-type dopant injection layer provided during the formation of the p-type Group III-V layer aids in providing a predetermined concentration, distribution and/or uniformity of the p-type dopant in the V-pits.
1. A light emitting diode (LED), comprising:
a substrate;
an n-doped Group III-V semiconductor layer adjacent the substrate;
a u-doped Group III-V layer adjacent the n-doped Group III-V semiconductor layer, the u-doped layer generating V-pits;
an active layer adjacent the u-doped Group III-V semiconductor layer, the active layer comprising a portion that extends into the V-pits;
an electron blocking layer adjacent the active layer, the electron blocking layer comprising a portion that extends into the V-pits; and
a p-doped Group III-V semiconductor layer adjacent the electron blocking layer, the p-doped Group III-V semiconductor layer comprising a portion that extends into the V-pits, wherein:
the portion of the p-doped Group III-V semiconductor layer that extends into the V-pits is a first portion;
the p-doped Group III-V semiconductor layer additionally comprises a second portion that does not extend into the V-pits; and
dopant characteristics of the first portion differ from dopant characteristics of the second portion.
2. The LED of claim 1 wherein a concentration of p-type dopant of the first portion is higher than a concentration of p-type dopant of the second portion.
3. The LED of claim 1 wherein a concentration of p-type dopant of the first portion is lower than a concentration of p-type dopant of the second portion.
4. The LED of claim 1 wherein a concentration of p-type dopant of the first portion increases as the first portion extends into a V-pit.
5. The LED of claim 1 wherein a concentration of p-type dopant of the second portion decreases as the second portion extends away from a V-pit.
6. The LED of claim 1 further comprising:
a wetting layer comprising a wetting material that aids in doping the p-doped Group III-V semiconductor layer.
7. The LED of claim 1 wherein the p-doped Group III-V semiconductor layer has a peak p-type dopant concentration adjacent the electron blocking layer.
8. The LED of claim 7 wherein the p-doped Group III-V semiconductor layer comprises indium having a peak concentration adjacent the electron blocking layer.
9. The LED of claim 7 wherein the p-doped Group III-V semiconductor layer comprises magnesium having a peak concentration adjacent the electron blocking layer.
10. The LED of claim 1 wherein the p-doped Group III-V semiconductor layer has a peak p-type dopant concentration formed at least by a p-type dopant injection layer.
11. The LED of claim 1 wherein the p-doped Group III-V semiconductor layer has a peak p-type dopant concentration formed at least by a wetting material.
12. The LED of claim 1 wherein elements of the electron blocking layer vary in concentration dependent on the elements' position within the electron blocking layer.
13. The LED of claim 1 wherein the active layer is a multiple quantum well active layer.
14. The LED of claim 1 wherein the active layer comprises alternating layers of a well layer and a barrier layer.
15. The LED of claim 1 wherein the active layer comprises alternating layers of indium gallium nitride and gallium nitride.
16. The LED of claim 1 wherein the active layer comprises alternating layers of indium aluminum gallium nitride and gallium nitride.
17. The LED of claim 1 wherein the active layer comprises gallium nitride and graded indium gallium nitride (In x Ga 1-x N), wherein “x” is a number between 0 and 1.
18. The LED of claim 1 wherein the u-doped Group III-V layer has a defect density between 1×10 8 cm −2 and 5×10 9 cm −2 .
19. The LED of claim 1 wherein the u-doped Group III-V layer has a defect density between 1×10 9 cm −2 and 2×10 9 cm −2 .
20. The LED of claim 1 wherein the electron blocking layer is aluminum gallium nitride (AlGaN).
21. The LED of claim 20 wherein the AlGaN is a graded Al x Ga 1-x N, wherein “x” is a number between 0 and 1.
22. The LED of claim 1 wherein the electron blocking layer is aluminum indium gallium nitride (AlInGaN).
23. The LED of claim 22 wherein the AlInGaN is a graded Al x In y Ga 1-x-y N, wherein “x” and “y” are a number between 0 and 1.
24. The LED of claim 1 further comprising:
a buffer layer between the substrate and the n-doped Group III-V semiconductor layer.
25. The LED of claim 24 wherein the buffer layer comprises:
an aluminum nitride (AlN) layer; and
an aluminum gallium nitride (AlGaN) layer.
26. The LED of claim 25 wherein the substrate is adjacent the AlN layer, the AlN layer is adjacent the AlGaN layer, and the AlGaN layer is adjacent the n-doped Group III-V semiconductor layer.
27. The LED of claim 1 wherein the concentration of the p-type dopant in the first portion is at a maximum at or near the active layer and decreases toward the second portion.
28. The LED of claim 1 wherein the concentration of the p-type dopant in the second portion is uniform along a longitudinal dimension of the V-pits.
29. The LED of claim 1 wherein the concentration of the p-type dopant in the second portion is uniform along a lateral dimension of the V-pits.