US5592501A
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US
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Low-strain laser structures with group III nitride active layers
Assignee: Wolfspeed Inc
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Filing: 1994-09-20
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Granted: 1997-01-07
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Expires: 2014-09-20
Abstract
Abstract A Group III nitride laser structure is disclosed with an active layer that includes at least one layer of a Group III nitride or an alloy of silicon carbide with a Group III nitride, a silicon carbide substrate, and a buffer layer between the active layer and the silicon carbide substrate. The buffer layer is selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, ternary Group III nitrides having the formula AxB1-xN, where A and B are Group III elements and where x is zero, one, or a fraction between zero and one, and alloys of silicon carbide with such ternary Group III nitrides. In preferred embodiments, the laser structure includes a strain-minimizing contact layer above the active layer that has a lattice constant substantially the same as the buffer layer.
Inventors
- 👤 John A. Edmond
- 👤 Gary E. Bulman
- 👤 Hua-Shuang Kong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:27
CPC Classifications
H; H10; H10H; H10H20/00; H10H20/80; H10H20/81; H10H20/822; H10H20/824; H10H20/825; B; B82; B82Y; B82Y20/00; H01; H01S; H01S5/00; H01S5/30; H01S5/32; H01S5/323; H01S5/32308; H01S5/32341; H01S5/34; H01S5/343; H10H20/01; H10H20/011; H10H20/013; H10H20/0133; H10H20/01335; H01S5/02; H01S5/0206; H01S5/021; H01S5/3201; H01S5/3223; H01S5/3224; H01S5/3226; H01S5/34333
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
48 words
A separate-confinement heterostructure laser comprising: an indium gallium nitride active layer; upper and lower waveguide layers on said active layer formed from the group consisting of AlGaN, InGaN, and AlInGaN; and upper and lower cladding layers on said respective upper and lower waveguide layers and formed of AlGaN.
Claim 2
Dependent Claim
48 words
A separate-confinement heterostructure laser comprising: an indium gallium nitride active layer; upper and lower waveguide layers on said active layer formed from the group consisting of AlGaN, InGaN, and AlInGaN; and upper and lower cladding layers on said respective upper and lower waveguide layers and formed of AlGaN.
Claim 3
Dependent Claim
20 words
A laser according to claim 1 and further comprising a strain minimizing AlGaN contact layer on said upper cladding layer.
Claim 4
Dependent Claim
31 words
A laser according to claim 1 wherein said waveguide layers have the formula Al x Ga 1-x N, and where x is 0, 1, or a fraction between 0 and 1.
Claim 5
Dependent Claim
42 words
A laser according to claim 1 wherein said waveguide layers have the formula Al x Ga y IN 1-x-y N, and where x and y are 0, 1, or a fraction between 0 and 1 and where 1 is greater than (x+y).
Claim 6
Dependent Claim
18 words
A laser according to claim 1 wherein said waveguide layers have a bandgap larger than said active layer.
Claim 7
Dependent Claim
19 words
A laser according to claim 1 wherein said waveguide layers have a refractive index smaller than said active layer.
Claim 8
Dependent Claim
37 words
A laser according to claim 3 wherein said cladding layers have the formula Al y Ga 1-y N wherein y is greater than x, and where y is 0, 1, or a fraction between 0 and 1.
Claim 9
Dependent Claim
18 words
A laser according to claim 1 wherein said cladding layers have a bandgap larger than said waveguide layers.
Claim 10
Dependent Claim
19 words
A laser according to claim 1 wherein said cladding layers have a refractive index smaller than said waveguide layers.
Claim 11
Dependent Claim
58 words
A laser according to claim 7 and further comprising a strain minimizing AlGaN contact layer on said upper cladding layer, and wherein said strain minimizing contact layer has the formula Al w Ga 1-w N wherein w is greater than x and less than y, and where w is 0, 1, or a fraction between 0 and 1.
Claim 12
Dependent Claim
43 words
A laser according to claim 1 wherein: said upper waveguide and upper cladding layers have the same conductivity type; said lower waveguide and lower cladding layers have the same conductivity type and that is opposite to the conductivity type of said upper layers.
Claim 13
Dependent Claim
18 words
A laser according to claim 11 wherein said upper layers are p-type and said lower layers are n-type.
Claim 14
Dependent Claim
29 words
A laser according to claim 12 and further comprising a strain minimizing AlGaN contact layer on said upper cladding layer, and wherein said strain minimizing contact layer is p-type.
Claim 15
Dependent Claim
41 words
A laser according to claim 1 wherein each of said waveguide and cladding layers has a thickness sufficient to substantially accommodate the strain between it and its adjacent layers, but less than the thickness at which misfit dislocations begin to form.
Claim 16
Dependent Claim
54 words
A laser according to claim 1 and further comprising: a silicon carbide substrate; and a buffer layer formed of one or more layers having a composition selected from the group consisting of GaN, AlN, InN, and Al x Ga 1-x N, and where x is zero, one, or a fraction between zero and one.
Claim 17
Dependent Claim
35 words
A laser according to claim 15 and further comprising a strain minimizing AlGaN contact layer on said upper cladding layer, and wherein said strain-minimizing contact layer has a lattice constant that matches said buffer layer.
Claim 18
Dependent Claim
52 words
A laser according to claim 15 and further comprising a strain minimizing AlGaN contact layer on said upper cladding layer, and wherein the lattice constant of said buffer layer is substantially the average of the lattice constants of said active layer, said waveguide layers, said cladding layers and said strain-minimizing contact layer.
Claim 19
Dependent Claim
25 words
A laser structure according to claim 1 wherein said active, waveguide, cladding, and contact layers have the composition and thicknesses set forth in Table I.
Claim 20
Dependent Claim
25 words
A laser structure according to claim 1 wherein said active, waveguide, cladding, and contact layers have the composition and thicknesses set forth in Table IIa.
Claim 21
Dependent Claim
25 words
A laser structure according to claim 1 wherein said active, waveguide, cladding, and contact layers have the composition and thicknesses set forth in Table IIb.
Claim 22
Dependent Claim
25 words
A laser structure according to claim 1 wherein said active, waveguide, cladding, and contact layers have the composition and thicknesses set forth in Table III.
Claim 23
Dependent Claim
49 words
A separate-confinement heterostructure laser comprising: an aluminum indium gallium nitride active layer; upper and lower waveguide layers on said active layer formed from the group consisting of AlGaN, InGaN, and AlInGaN; and upper and lower cladding layers on said respective upper and lower waveguide layers and formed of AlGaN.
Claim 24
Dependent Claim
49 words
A separate-confinement heterostructure laser comprising: an aluminum indium gallium nitride active layer; upper and lower waveguide layers on said active layer formed from the group consisting of AlGaN, InGaN, and AlInGaN; and upper and lower cladding layers on said respective upper and lower waveguide layers and formed of AlGaN.
Claim 25
Dependent Claim
43 words
A laser structure according to claim 22 wherein said active layer has the composition Al x Ga y In 1-x-y N, and where x and y are 0, 1, or a fraction between 0 and 1 and where 1 is greater than (x+y).
Claim 26
Dependent Claim
83 words
A group III nitride laser structure comprising: an active layer that includes at least one layer of a Group III nitride; a silicon carbide substrate; and a coupling structure between said active layer and said substrate, said coupling layer including at least one graded layer of silicon carbide and a group III nitride in which the graded layer is silicon carbide at the interface with said substrate, and the graded layer is the group III nitride at the interface with said active layer.
Claim 27
Dependent Claim
83 words
A group III nitride laser structure comprising: an active layer that includes at least one layer of a Group III nitride; a silicon carbide substrate; and a coupling structure between said active layer and said substrate, said coupling layer including at least one graded layer of silicon carbide and a group III nitride in which the graded layer is silicon carbide at the interface with said substrate, and the graded layer is the group III nitride at the interface with said active layer.
Claim 28
Dependent Claim
83 words
A laser according to claim 24 wherein said Group III nitride in said active layer is selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, ternary Group III nitrides having the formula A x B y C 1-x-y N, where A, B and C are Group III elements and where x and y are zero, one, or a fraction between zero and one and 1 is greater than (x+y), and alloys of silicon carbide with such ternary Group III nitrides.
Claim 29
Dependent Claim
36 words
A laser according to claim 25 and further comprising a strain-minimizing layer above said active layer, said strain-minimizing layer having a lattice constant that is substantially the same as the lattice constant of said coupling structure.
Claim 30
Dependent Claim
44 words
A laser according to claim 24 wherein said active layer further comprises: respective upper and lower waveguide layers adjacent both surfaces of said active layer; an upper cladding layer on said upper waveguide layer; and a lower cladding layer below said lower waveguide layer.
Claim 31
Dependent Claim
40 words
A laser according to claim 27 wherein said waveguide layers have a wider bandgap and a lower refractive index than said active layer; and said cladding layers have a wider bandgap and a lower refractive index than said waveguide layers.
Claim 32
Dependent Claim
17 words
A laser according to claim 27 wherein said strain minimizing layer is on said upper cladding layer.
Claim 33
Dependent Claim
16 words
A laser according to claim 29 wherein said lower cladding layer is on said coupling structure.
Claim 34
Dependent Claim
118 words
A group III nitride laser structure comprising: an active layer that includes at least one layer of a Group III nitride; a silicon carbide substrate; a buffer layer between said active layer and said silicon carbide substrate, said buffer layer being selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, ternary Group III nitrides having the formula A x B 1-x N, where A and B are Group III elements and where x is zero, one, or a fraction between zero and one, and alloys of silicon carbide with such ternary Group III nitrides; and a strain-minimizing contact layer above said active layer that has a lattice constant substantially the same as said buffer layer.
Claim 35
Dependent Claim
118 words
A group III nitride laser structure comprising: an active layer that includes at least one layer of a Group III nitride; a silicon carbide substrate; a buffer layer between said active layer and said silicon carbide substrate, said buffer layer being selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, ternary Group III nitrides having the formula A x B 1-x N, where A and B are Group III elements and where x is zero, one, or a fraction between zero and one, and alloys of silicon carbide with such ternary Group III nitrides; and a strain-minimizing contact layer above said active layer that has a lattice constant substantially the same as said buffer layer.
Claim 36
Dependent Claim
45 words
A laser structure according to claim 31 wherein said active layer further comprises: respective upper and lower waveguide layers adjacent both surfaces of said active layer; an upper cladding layer on said upper waveguide layer; and a lower cladding layer below said lower waveguide layer.
Claim 37
Dependent Claim
18 words
A laser structure according to claim 32 wherein said strain minimizing layer is on said upper cladding layer.
Claim 38
Dependent Claim
17 words
A laser structure according to claim 32 wherein said lower cladding layer is on said buffer layer.
Claim 39
Dependent Claim
40 words
A laser according to claim 32 wherein said waveguide layers have a wider bandgap and a lower refractive index than said active layer; and said cladding layers have a wider bandgap and a lower refractive index than said waveguide layers.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2000-01-07 | 2000-07-08 | 2001-01-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-01-07 | 2004-07-08 | 2005-01-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-01-07 | 2008-07-08 | 2009-01-07 | $7700.00 | Window Closed / Lapsed |