AlGaInN LED and laser diode structures for pure blue or green emission
First Claim
1. A semiconductor structure, comprising:
- a nucleation layer;
a thick InGaN layer grown directly on the nucleation layer; and
an active layer formed over the thick InGaN layer, the active layer comprising at least one quantum well.
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Abstract
Group III-V nitride semiconductors are used as optoelectronic light emitters. The semiconductor alloy InGaN is used as the active region in nitride laser diodes and LEDs, as its bandgap energy can be tuned by adjusting the alloy composition, to span the entire visible spectrum. InGaN layers of high-indium content, as required for blue or green emission are difficult to grow, however, because the poor lattice mismatch between GaN and InGaN causes alloy segregation. In this situation, the inhomogeneous alloy composition results in spectrally impure emission, and diminished optical gain. To suppress segregation, the high-indium-content InGaN active region may be deposited over a thick InGaN layer, substituted for the more typical GaN. First depositing a thick InGaN layer establishes a larger lattice parameter than that of GaN. Consequently, a high indium content heterostructure active region grown over the thick InGaN layer experiences significantly less lattice mismatch compared to GaN. Therefore, it is less likely to suffer structural degradation due to alloy segregation. Thus, the thick GaN structure enables the growth of a high indium content active region with improved structural and optoelectronic properties, leading to LEDs with spectrally pure emission, and lower threshold laser diodes.
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Citations
37 Claims
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1. A semiconductor structure, comprising:
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a nucleation layer;
a thick InGaN layer grown directly on the nucleation layer; and
an active layer formed over the thick InGaN layer, the active layer comprising at least one quantum well. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 33, 34)
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11. An image forming apparatus that forms an image on a light sensitive medium, the image forming apparatus comprising at least one light source that includes a semiconductor structure including:
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a nucleation layer;
a thick InGaN layer grown directly on the nucleation layer; and
an active layer formed over the thick InGaN layer, the active layer comprising at least one quantum well. - View Dependent Claims (12, 13)
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14. A data storage apparatus that stores data on a medium, the data storage apparatus comprising at least one light source that includes a semiconductor structure including:
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a nucleation layer;
a thick InGaN layer grown directly on the nucleation layer; and
an active layer formed over the thick InGaN layer, the active layer comprising at least one quantum well. - View Dependent Claims (15, 16, 17)
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18. A communications apparatus that communicates information through a communications transmission medium, the communications apparatus comprising at least one light source that includes a semiconductor structure including:
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a nucleation layer;
a thick InGaN layer grown directly on the nucleation layer; and
an active layer formed over the thick InGaN layer, the active layer comprising at least one quantum well. - View Dependent Claims (19, 20)
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21. A method of forming a semiconductor structure, comprising the steps of:
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forming a nucleation layer;
forming a thick InGaN layer directly on the nucleation layer; and
forming an active layer over the thick InGaN layer, the active layer comprising at least one quantum well. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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35. A laser diode, comprising:
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a nucleation layer;
a thick InGaN layer grown directly on the nucleation layer; and
an active layer formed over the thick InGaN layer, the active layer including an InGaN quantum well active region. - View Dependent Claims (36, 37)
a first group III-V nitride cladding layer on the thick InGaN layer;
the InGaN quantum well active region formed over the first group III-V nitride cladding layer; and
a second group III-V nitride cladding layer over the InGaN quantum well active region.
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37. The laser diode according to claim 36, wherein the laser diode emits light with a wavelength within a range of from 430 nm to 650 nm.
Specification