LED efficiency using photonic crystal structure
First Claim
1. A light emitting diode comprising:
- a first semiconductor layer doped with a first dopant, coupled to a first electrode layer;
an active layer overlying said first semiconductor layer, capable of emitting light;
a second semiconductor layer doped with a second dopant, overlying said active layer, said first dopant and said second dopant being of opposite type; and
a second electrode layer overlying said second semiconductor layer, wherein at least one of said active layer and said second semiconductor layer has a periodically varying thickness with alternating maxima and minima, wherein the ratio of the period of said periodic variation and the wavelength of said emitted light in air is greater than about 0.1 and less than about 5; and
the thickness of said second semiconductor layer at said minima is less than about one wavelength of said emitted light in said second semiconductor layer.
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Accused Products
Abstract
A photonic crystal light emitting diode (“PXLED”) is provided. The PXLED includes a periodic structure, such as a lattice of holes, formed in the semiconductor layers of an LED. The parameters of the periodic structure are such that the energy of the photons, emitted by the PXLED, lies close to a band edge of the band structure of the periodic structure. Metal electrode layers have a strong influence on the efficiency of the PXLEDs. Also, PXLEDs formed from GaN have a low surface recombination velocity and hence a high efficiency. The PXLEDs are formed with novel fabrication techniques, such as the epitaxial lateral overgrowth technique over a patterned masking layer, yielding semiconductor layers with low defect density. Inverting the PXLED to expose the pattern of the masking layer or using the Talbot effect to create an aligned second patterned masking layer allows the formation of PXLEDs with low defect density.
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Citations
92 Claims
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1. A light emitting diode comprising:
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a first semiconductor layer doped with a first dopant, coupled to a first electrode layer;
an active layer overlying said first semiconductor layer, capable of emitting light;
a second semiconductor layer doped with a second dopant, overlying said active layer, said first dopant and said second dopant being of opposite type; and
a second electrode layer overlying said second semiconductor layer, wherein at least one of said active layer and said second semiconductor layer has a periodically varying thickness with alternating maxima and minima, wherein the ratio of the period of said periodic variation and the wavelength of said emitted light in air is greater than about 0.1 and less than about 5; and
the thickness of said second semiconductor layer at said minima is less than about one wavelength of said emitted light in said second semiconductor layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A light emitting diode comprising:
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a first semiconductor layer doped with a first dopant;
an active layer overlying said first semiconductor layer, capable of emitting light; and
a second semiconductor layer doped with a second dopant overlying said active layer, said first and second dopants being of opposite type, wherein at least one of said active layer and said second semiconductor layer has a periodically varying thickness with alternating maxima and minima, wherein the ratio of the period of said periodic variation and the wavelength of said emitted light in air is greater than about 0.1 and less than about 5; and
the thickness of said second semiconductor layer at said minima is less than about one wavelength of said emitted light in said second semiconductor layer; and
at least one of said first semiconductor layer, said active layer, and said second semiconductor layer comprises a group III element and a group V element. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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47. A method of making a light emitting diode, the method comprising:
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providing a semiconductor structure, comprising;
a substrate;
a plurality of semiconductor layers, capable of emitting light, overlying said substrate;
a top electrode layer, overlying said plurality of semiconductor layers; and
a photosensitive layer overlying said top electrode layer, having a planar lattice of openings, wherein the ratio of the period of said planar lattice of openings and the wavelength of said emitted light in air is greater than about 0.1 and less than about 5; and
forming a planar lattice of holes by removing said top electrode layer and at least partially removing said plurality of semiconductor layers at regions corresponding to said planar lattice of openings. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54, 55, 56)
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57. A method of making a light emitting diode, the method comprising:
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providing a semiconductor structure, comprising;
a first substrate;
a masking layer with a first planar lattice of openings, overlying said substrate;
a plurality of semiconductor layers, capable of emitting light, overlying said first substrate, wherein the ratio of the period of said planar lattice of openings and the wavelength of said emitted light in air is greater than about 0.1 and less than about 5; and
forming a planar lattice of holes in said plurality of semiconductor layers by at least partially removing said plurality of semiconductor layers in regions corresponding to said first planar lattice of openings of said masking layer. - View Dependent Claims (58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74)
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75. A method of making a light emitting diode, the method comprising:
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providing a semiconductor structure, comprising;
a substrate;
a masking layer with a first planar lattice of openings, overlying said substrate;
a plurality of semiconductor layers, overlying said masking layer; and
a photosensitive layer, overlying said plurality of semiconductor layers;
shining light at said first planar lattice of openings from the direction of said substrate; and
creating images of said openings of said first planar lattice of openings on said photosensitive layer by causing the diffraction of said shined light. - View Dependent Claims (76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92)
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Specification