III-nitride semiconductor light emitting device having amber-to-red light emission (>600 nm) and a method for making same
First Claim
1. A III-nitride semiconductor LED comprising:
- a plurality of multiple quantum well sets stacked on a substrate, the plurality of multiple quantum well sets including a first, a second, and a top multiple quantum well set;
the first multiple quantum well set being adjacent the substrate and having a low indium concentration;
each multiple quantum well set above the first multiple quantum well set having a progressively increased indium concentration;
the top multiple quantum well set having a highest indium concentration selected to emit light in the amber-to-red visible spectra region; and
adjacent multiple quantum well sets being separated by an AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer, each AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer having a barrier layer above and below the respective AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer to reduce total strain in the top multiple quantum well set,wherein an Al concentration in the AlxGa1-xN (0<
x≤
1) intermediate strain compensation layers is varied with the AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer closest to the substrate having higher Al concentration than the other AlxGa1-xN (0<
x≤
1) intermediate strain compensation layers.
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Accused Products
Abstract
A III-nitride semiconductor light emitting device incorporating n-type III-nitride cladding layers, indium containing III-nitride light emitting region, and p-type III-nitride cladding layers. The light emitting region is sandwiched between n- and p-type III-nitride cladding layers and includes multiple sets of multi-quantum-wells (MQWs). The first MQW set formed on the n-type cladding layer comprises relatively lower indium concentration. The second MQW set comprising relatively moderate indium concentration. The third MQW set adjacent to the p-type cladding layer incorporating relatively highest indium concentration of the three MQW sets and is capable of emitting amber-to-red light. The first two MQW sets are utilized as pre-strain layers. Between the MQW sets, intermediate strain compensation layers (ISCLs) are added. The combination of the first two MQW sets and ISCLs prevent phase separation and enhance indium uptake in the third MQW set. The third MQW set, as a result, retains sufficiently high indium concentration to emit amber-to-red light of high output power without any phase separation associated problems.
83 Citations
22 Claims
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1. A III-nitride semiconductor LED comprising:
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a plurality of multiple quantum well sets stacked on a substrate, the plurality of multiple quantum well sets including a first, a second, and a top multiple quantum well set; the first multiple quantum well set being adjacent the substrate and having a low indium concentration; each multiple quantum well set above the first multiple quantum well set having a progressively increased indium concentration; the top multiple quantum well set having a highest indium concentration selected to emit light in the amber-to-red visible spectra region; and adjacent multiple quantum well sets being separated by an AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer, each AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer having a barrier layer above and below the respective AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer to reduce total strain in the top multiple quantum well set,wherein an Al concentration in the AlxGa1-xN (0<
x≤
1) intermediate strain compensation layers is varied with the AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer closest to the substrate having higher Al concentration than the other AlxGa1-xN (0<
x≤
1) intermediate strain compensation layers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of forming a III-nitride semiconductor LED comprising:
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forming over a substrate an active region having a plurality of sets of multiple quantum wells by; forming over the substrate, the first set of multiple quantum wells having an indium concentration; forming at least two additional sets of multiple quantum wells over the first set of multiple quantum wells, the formation of each additional set of multiple quantum wells being preceded by the formation of an AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer over the preceding set of multiple quantum wells such that a first AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer and a second AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer are formed;the at least two additional set of multiple quantum wells having a higher indium concentration than the first set of multiple quantum wells; and the first AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer closest to the substrate containing a higher Al concentration than the second AlxGa1-xN (0<
x≤
1) intermediate strain compensation layer. - View Dependent Claims (11, 12, 13)
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14. A multilayer III-nitride semiconductor LED comprising:
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first, second and third layered multiple quantum well sets stacked on a substrate in ascending order with the first layered multiple quantum well set closest to the substrate; the first layered multiple quantum well set having a first indium concentration; the second layered multiple quantum well set having a second indium concentration that is greater than the first indium concentration; the third layered multiple quantum well set having a third indium concentration that is greater than the second indium concentration; a first intermediate strain compensation layer comprised of AlxGa1-xN (0<
x≤
1) disposed between the first and second layered multiple quantum well sets;a second intermediate strain compensation layer comprised of AlxGa1-xN (0<
x≤
1) disposed between the second and third layered multiple quantum well sets;the first and second intermediate strain compensation layers each being disposed between two barrier layers; and the third layered multiple quantum well set being configured to emit light having a peak emission at a wavelength ranging from approximately 600 nm to approximately 660 nm, wherein the first intermediate strain compensation layer comprises a higher Al concentration than the second intermediate strain compensation layer. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A method of manufacturing a III-nitride semiconductor LED which emits amber-to-red light, comprising:
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defining a first barrier layer; defining a first layered multiple quantum well set comprising a first indium concentration on the first barrier layer; defining a second barrier layer on the first layered multiple quantum well set; defining a first intermediate strain compensation layer comprised of AlxGa1-xN (0<
x≤
1) on the second barrier layer;defining a third barrier layer on the first intermediate-strain compensation layer; defining on the third barrier layer, a second layered multiple quantum well set comprising a second indium concentration that is greater than the first indium concentration; defining a fourth barrier layer on the second layered multiple quantum well set; defining a second intermediate strain compensation layer comprised of AlxGa1-xN (0<
x≤
1) on the fourth barrier layer;defining a fifth barrier layer on the second intermediate strain compensation layer; and defining a third layered multiple quantum well set comprising a third indium concentration that is greater than the second indium concentration configured to emit light having a peak emission at a wavelength ranging from approximately 600 nm to approximately 660 nm, wherein the first intermediate strain compensation layer comprises a higher Al concentration than the second intermediate strain compensation layer. - View Dependent Claims (22)
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Specification