Ultraviolet light emitting devices having compressively strained light emitting layer for enhanced light extraction
First Claim
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1. A nitride-semiconductor light emitting device comprising:
- a substrate;
a first heterostructure;
a second heterostructure;
a light emitting region comprising;
barrier layers comprising AlGaN; and
one or more quantum wells comprising AlGaN, each quantum well respectively disposed between two of the barrier layers, the light emitting region disposed between the first and second heterostructures and configured to emit light having a central wavelength, λ
, and a degree of polarization, PD, where PD>
0.006λ
−
b for 200 nm≤
λ
≤
400 nm, wherein b≤
1.5, wherein the first heterostructure is disposed between the light emitting region and the substrate and includes a transition layer comprising a two section AlN/GaN superlattice, the two section AlN/GaN superlattice having a first surface near the substrate and a second surface near the light emitting region, the two section superlattice configured to transition Al content of the device from a higher Al content near the first surface to a lower Al content near the second surface.
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Abstract
Light emitting devices having an enhanced degree of polarization, PD, and methods for fabricating such devices are described. A light emitting device may include a light emitting region that is configured to emit light having a central wavelength, λ, and a degree of polarization, PD, where PD>0.006λ−b for 200 nm≤λ≤400 nm, wherein b≤1.5.
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Citations
15 Claims
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1. A nitride-semiconductor light emitting device comprising:
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a substrate; a first heterostructure; a second heterostructure; a light emitting region comprising; barrier layers comprising AlGaN; and one or more quantum wells comprising AlGaN, each quantum well respectively disposed between two of the barrier layers, the light emitting region disposed between the first and second heterostructures and configured to emit light having a central wavelength, λ
, and a degree of polarization, PD, where PD>
0.006λ
−
b for 200 nm≤
λ
≤
400 nm, wherein b≤
1.5, wherein the first heterostructure is disposed between the light emitting region and the substrate and includes a transition layer comprising a two section AlN/GaN superlattice, the two section AlN/GaN superlattice having a first surface near the substrate and a second surface near the light emitting region, the two section superlattice configured to transition Al content of the device from a higher Al content near the first surface to a lower Al content near the second surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A nitride semiconductor light emitting device, comprising:
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a bulk crystalline AlN substrate; a light emitting region comprising AlGaN grown above the bulk crystalline AlN substrate; and a first heterostructure disposed between the light emitting region and the bulk crystalline AlN substrate, the first heterostructure including a transition layer comprising an AlN/GaN superlattice, wherein variation in reciprocal lattice values of the bulk crystalline AlN substrate and the light emitting region is less than about 1.5% and wherein the light emitting region is configured to emit light having a central wavelength, λ
, and a degree of polarization, PD, where PD is greater than 0.006λ
−
1.5 for 200≤
λ
≤
400 nm, the AlN/GaN superlattice having a first surface near the substrate and a second surface near the light emitting region, an Al content of the AlN/GaN superlattice changing from a higher Al content near the first surface to a lower Al content near the second surface. - View Dependent Claims (14, 15)
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Specification