Polarization doping in nitride based diodes
First Claim
1. A light emitting device, comprising:
- an n-type semiconductor layer;
a p-type semiconductor layer;
an active region interposed between said n-type layer and said p-type layer; and
a three-dimensional polarization-graded (3DPG) structure disposed on said n-type layer opposite said active region, said 3DPG structure comprising at least one repeatable stack unit, said 3DPG structure having a wurtzite crystal structure grown along the [0001]-crystal direction;
wherein said repeatable stack unit comprises;
a retrograded layer that is compositionally retrograded from a first material to a second material over a grading distance, said retrograded layer disposed proximate to said n-type layer such that said second material is closest to said n-type layer; and
a silicon (Si) delta-doped layer disposed adjacent to said retrograded layer opposite said n-type layer.
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Accused Products
Abstract
A light emitting device comprising a three-dimensional polarization-graded (3DPG) structure that improves lateral current spreading within the device without introducing additional dopant impurities in the epitaxial structures. The 3DPG structure can include a repeatable stack unit that may be repeated several times within the 3DPG. The stack unit includes a compositionally graded layer and a silicon (Si) delta-doped layer. The graded layer is compositionally graded over a distance from a first material to a second material, introducing a polarization-induced bulk charge into the structure. The Si delta-doped layer compensates for back-depletion of the electron gas at the interface of the graded layers and adjacent layers. The 3DPG facilitates lateral current spreading so that current is injected into the entire active region, increasing the number of radiative recombination events in the active region and improving the external quantum efficiency and the wall-plug efficiency of the device.
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Citations
32 Claims
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1. A light emitting device, comprising:
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an n-type semiconductor layer; a p-type semiconductor layer; an active region interposed between said n-type layer and said p-type layer; and a three-dimensional polarization-graded (3DPG) structure disposed on said n-type layer opposite said active region, said 3DPG structure comprising at least one repeatable stack unit, said 3DPG structure having a wurtzite crystal structure grown along the [0001]-crystal direction; wherein said repeatable stack unit comprises; a retrograded layer that is compositionally retrograded from a first material to a second material over a grading distance, said retrograded layer disposed proximate to said n-type layer such that said second material is closest to said n-type layer; and a silicon (Si) delta-doped layer disposed adjacent to said retrograded layer opposite said n-type layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A current spreading device, comprising:
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a retrograded layer that is compositionally retrograded from a first material to a second material over a grading distance; and a silicon (Si) delta-doped layer disposed adjacent to said retrograded layer, such that said first material is proximate to said Si delta-doped layer; an n-type spacer layer disposed adjacent to said Si delta-doped layer opposite said retrograded layer such that said Si delta-doped layer is interposed between said retrograded layer and said spacer layer; wherein said retrograded layer, said Si delta-doped layer, and said n-type spacer layer are arranged in a repeatable stack that is repeated 15-20 times within said current spreading device. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A semiconductor device, comprising:
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a retrograded layer that is compositionally retrograded from a first material to a second material over a grading distance; and a silicon (Si) delta-doped layer disposed adjacent to said graded layer, such that said first material is proximate to said Si delta-doped layer; wherein said first material comprises indium gallium nitride of a first composition (InxGa1-xN) where x is approximately 0.1, and said second material comprises gallium nitride (GaN).
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27. A semiconductor device, comprising:
multiple stack units, each said stack unit comprising; a retrograded layer that is compositionally retrograded from a first material to a second material over a grading distance, said first material comprising a component material in a first percentage and said second material comprising a lower percentage of said component material than said first material; a uniformly doped spacer layer; and a delta-doped layer interposed between said retrograded layer and said uniformly doped spacer layer, wherein said retrograded layer first material is directly adjacent to said delta-doped layer. - View Dependent Claims (28, 29, 31, 32)
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30. A semiconductor device, comprising:
multiple stack units, each said stack unit comprising; a retrograded layer that is compositionally retrograded from a first material to a second material over a grading distance, said first material comprising a component material in a first percentage and said second material comprising a lower percentage of said component material than said first material; a uniformly doped spacer layer, wherein said retrograded layer and said spacer layer both comprise n-type semiconductor materials; and a delta-doped layer interposed between said retrograded layer and said uniformly doped spacer layer, wherein said retrograded layer first material is adjacent to said delta-doped layer.
Specification