US5338944A
Expired / Lapsed
US
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Blue light-emitting diode with degenerate junction structure
Assignee: Wolfspeed Inc
•
Filing: 1993-09-22
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Granted: 1994-08-16
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Expires: 2013-09-22
Abstract
Abstract A light emitting diode is disclosed that emits light in the blue region of the visible spectrum with increased brightness and efficiency. The light emitting diode comprises an n-type silicon carbide substrate; an n-type silicon carbide top layer; and a light emitting p-n junction structure between the n-type substrate and the n-type top layer. The p-n junction structure is formed of respective portions of n-type silicon carbide and p-type silicon carbide. The diode further includes means between the n-type top layer and the n-type substrate for coupling the n-type top layer to the light-emitting p-n junction structure while preventing n-p-n behavior between the n-type top layer, the p-type layer in the junction structure, and the n-type substrate.
Inventors
- 👤 John A. Edmond
- 👤 Hua-Shuang Kong
- 👤 Vladimir Dmitriev
- 👤 Gary E. Bulman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:52
CPC Classifications
H; H10; H10H; H10H20/00; H10H20/80; H10H20/81; H10H20/822; H10H20/826; H01; H01S; H01S5/00; H01S5/30; H01S5/305; H01S5/3095
Claims Analysis
Total Claims: 51
Claim 1
Independent Claim
110 words
A light emitting diode that emits light in the blue region of the visible spectrum with increased brightness and efficiency, said light emitting diode comprising: an n-type silicon carbide substrate; an n-type silicon carbide top layer; a light emitting p-n junction structure between said n-type substrate and said n-type top layer, said p-n junction being formed of respective portions of n-type silicon carbide and p-type silicon carbide; and means between said n-type top layer and said n-type substrate for coupling said n-type top layer to said light-emitting p-n junction structure while preventing n-p-n behavior between said n-type top layer, said p-type portion in said junction structure, and said n-type substrate.
Claim 2
Dependent Claim
110 words
A light emitting diode that emits light in the blue region of the visible spectrum with increased brightness and efficiency, said light emitting diode comprising: an n-type silicon carbide substrate; an n-type silicon carbide top layer; a light emitting p-n junction structure between said n-type substrate and said n-type top layer, said p-n junction being formed of respective portions of n-type silicon carbide and p-type silicon carbide; and means between said n-type top layer and said n-type substrate for coupling said n-type top layer to said light-emitting p-n junction structure while preventing n-p-n behavior between said n-type top layer, said p-type portion in said junction structure, and said n-type substrate.
Claim 3
Dependent Claim
55 words
A light emitting diode according to claim 1 wherein said coupling means comprises a degenerate junction structure, said degenerate junction structure being formed of a p-type portion and an n-type portion of silicon carbide, with said p-type portion of said degenerate junction structure being adjacent said p-type layer of silicon carbide in said junction structure.
Claim 4
Dependent Claim
50 words
A light emitting diode according to claim 2 wherein said doping in said p-type portion and said n-type portion in said degenerate junction structure is sufficiently heavy to substantially eliminate the barrier between the p-type portion and the n-type portion of the silicon carbide from which the portions are formed.
Claim 5
Dependent Claim
29 words
A light emitting diode according to claim 2 wherein said degenerate junction structure is on said substrate and said light emitting junction structure is on said degenerate junction structure.
Claim 6
Dependent Claim
30 words
A light emitting diode according to claim 2 wherein said light emitting junction structure is on said substrate and said degenerate junction structure is on said light emitting junction structure.
Claim 7
Dependent Claim
27 words
A light emitting diode according to claim 1 and further comprising an ohmic contact to said n-type substrate and an ohmic contact to said n-type top layer.
Claim 8
Dependent Claim
31 words
A light emitting diode according to claim 2 wherein said n-type portion of silicon carbide and said p-type portion of silicon carbide in said junction structure are each an epitaxial layer.
Claim 9
Dependent Claim
29 words
A light emitting diode according to claim 2 wherein said degenerate junction structure comprises an epitaxial layer of p-type silicon carbide and an epitaxial layer of n-type silicon carbide.
Claim 10
Dependent Claim
36 words
A light emitting diode according to claim 8 wherein said p-type layer and said n-type layer in said degenerate junction structure are thin enough to substantially avoid absorption of light emitted from said light emitting junction.
Claim 11
Dependent Claim
15 words
A light emitting diode according to claim 1 wherein said substrate is a single crystal.
Claim 12
Dependent Claim
28 words
A light emitting diode according to claim 10 wherein said substrate has a polytype of silicon carbide selected from the group consisting of 3C, 4H, 6H, and 15R.
Claim 13
Dependent Claim
17 words
A light emitting diode according to claim 1 wherein said n-type top layer comprises an epitaxial layer.
Claim 14
Dependent Claim
126 words
A light emitting diode that emits light in the blue region of the visible spectrum with increased brightness and efficiency, said light emitting diode comprising: an n-type silicon carbide substrate; an n-type epitaxial layer of silicon carbide on said n-type substrate; a compensated p-type epitaxial layer of silicon carbide on said n-type layer and defining a light emitting p-n junction between said p-type layer and said n-type layer; a degenerate junction on said p-type layer, said degenerate junction being formed of a p-type epitaxial layer and an n-type epitaxial layer of silicon carbide, with said p-type portion of said degenerate junction being adjacent said p-type layer of silicon carbide; and a second epitaxial layer of n-type silicon carbide on said n-type layer of said degenerate junction.
Claim 15
Dependent Claim
126 words
A light emitting diode that emits light in the blue region of the visible spectrum with increased brightness and efficiency, said light emitting diode comprising: an n-type silicon carbide substrate; an n-type epitaxial layer of silicon carbide on said n-type substrate; a compensated p-type epitaxial layer of silicon carbide on said n-type layer and defining a light emitting p-n junction between said p-type layer and said n-type layer; a degenerate junction on said p-type layer, said degenerate junction being formed of a p-type epitaxial layer and an n-type epitaxial layer of silicon carbide, with said p-type portion of said degenerate junction being adjacent said p-type layer of silicon carbide; and a second epitaxial layer of n-type silicon carbide on said n-type layer of said degenerate junction.
Claim 16
Dependent Claim
21 words
A light emitting diode according to claim 13 wherein said n-type epitaxial layer on said substrate is a compensated n-type layer.
Claim 17
Dependent Claim
32 words
A light emitting diode according to claim 14 wherein said compensated n-type epitaxial layer has a carrier concentration greater than said compensated p-type layer so that electron injection predominates across said junction.
Claim 18
Dependent Claim
23 words
A light emitting diode according to claim 13 and further comprising an ohmic contact to said second epitaxial layer of n-type silicon carbide.
Claim 19
Dependent Claim
14 words
A light emitting diode according to claim 16 wherein said ohmic contact comprises nickel.
Claim 20
Dependent Claim
35 words
A light emitting diode according to claim 13 and further comprising a third epitaxial layer of n-type silicon carbide on said second epitaxial layer, said third layer being more heavily doped than said second layer.
Claim 21
Dependent Claim
23 words
A light emitting diode according to claim 18 and further comprising an ohmic contact to said third epitaxial layer of n-type silicon carbide.
Claim 22
Dependent Claim
14 words
A light emitting diode according to claim 19 wherein said ohmic contact comprises nickel.
Claim 23
Dependent Claim
18 words
A light emitting diode according to claim 13 and further comprising an ohmic contact to said n-type substrate.
Claim 24
Dependent Claim
14 words
A light emitting diode according to claim 21 wherein said ohmic contact comprises nickel.
Claim 25
Dependent Claim
29 words
A light emitting diode according to claim 13 and further comprising a fourth epitaxial buffer layer of n-type silicon carbide between said substrate and said light emitting junction structure.
Claim 26
Dependent Claim
55 words
A light emitting diode according to claim 13 wherein said doping in said p-type layer and said n-type layer in said degenerate junction is sufficiently heavy to substantially eliminate the barrier between the p-type layer and the n-type layer to be greater than the bandgap of the silicon carbide from which said layers are formed.
Claim 27
Dependent Claim
35 words
A light emitting diode according to claim 13 wherein said p-type layer and said n-type layer in said degenerate junction are thin enough to substantially avoid absorption of light emitted from said light emitting junction.
Claim 28
Dependent Claim
15 words
A light emitting diode according to claim 13 wherein said substrate is a single crystal.
Claim 29
Dependent Claim
28 words
A light emitting diode according to claim 26 wherein said substrate has a polytype of silicon carbide selected from the group consisting of 3C, 4H, 6H, and 15R.
Claim 30
Dependent Claim
127 words
A light emitting diode that emits light in the blue region of the visible spectrum with increased brightness and efficiency, said light emitting diode comprising: an n-type silicon carbide substrate; a degenerate junction on said n-type substrate, said degenerate junction diode being formed of a p-type epitaxial layer and an n-type epitaxial layer of silicon carbide, with said n-type layer of said degenerate junction being adjacent said n-type substrate; a compensated p-type epitaxial layer of silicon carbide on said p-type layer of said degenerate junction; an n-type epitaxial layer of silicon carbide on said compensated p-type epitaxial layer, and defining a light emitting p-n junction between said p-type layer and said n-type layer; and a second epitaxial layer of n-type silicon carbide on said compensated n-type layer.
Claim 31
Dependent Claim
127 words
A light emitting diode that emits light in the blue region of the visible spectrum with increased brightness and efficiency, said light emitting diode comprising: an n-type silicon carbide substrate; a degenerate junction on said n-type substrate, said degenerate junction diode being formed of a p-type epitaxial layer and an n-type epitaxial layer of silicon carbide, with said n-type layer of said degenerate junction being adjacent said n-type substrate; a compensated p-type epitaxial layer of silicon carbide on said p-type layer of said degenerate junction; an n-type epitaxial layer of silicon carbide on said compensated p-type epitaxial layer, and defining a light emitting p-n junction between said p-type layer and said n-type layer; and a second epitaxial layer of n-type silicon carbide on said compensated n-type layer.
Claim 32
Dependent Claim
21 words
A light emitting diode according to claim 28 wherein said n-type epitaxial layer on said substrate is a compensated n-type layer.
Claim 33
Dependent Claim
32 words
A light emitting diode according to claim 29 wherein said compensated n-type epitaxial layer has a carrier concentration greater than said compensated p-type layer so that electron injection predominates across said junction.
Claim 34
Dependent Claim
23 words
A light emitting diode according to claim 28 and further comprising an ohmic contact to said second epitaxial layer of n-type silicon carbide.
Claim 35
Dependent Claim
14 words
A light emitting diode according to claim 31 wherein said ohmic contact comprises nickel.
Claim 36
Dependent Claim
35 words
A light emitting diode according to claim 28 and further comprising a third epitaxial layer of n-type silicon carbide on said second epitaxial layer, said third layer being more heavily doped than said second layer.
Claim 37
Dependent Claim
23 words
A light emitting diode according to claim 33 and further comprising an ohmic contact to said third epitaxial layer of n-type silicon carbide.
Claim 38
Dependent Claim
14 words
A light emitting diode according to claim 34 wherein said ohmic contact comprises nickel.
Claim 39
Dependent Claim
18 words
A light emitting diode according to claim 28 and further comprising an ohmic contact to said n-type substrate.
Claim 40
Dependent Claim
14 words
A light emitting diode according to claim 36 wherein said ohmic contact comprises nickel.
Claim 41
Dependent Claim
55 words
A light emitting diode according to claim 28 wherein said doping in said p-type layer and said n-type layer in said degenerate junction is sufficiently heavy to substantially eliminate the barrier between the p-type layer and the n-type layer to be greater than the bandgap of the silicon carbide from which said layers are formed.
Claim 42
Dependent Claim
35 words
A light emitting diode according to claim 28 wherein said p-type layer and said n-type layer in said degenerate junction are thin enough to substantially avoid absorption of light emitted from said light emitting junction.
Claim 43
Dependent Claim
15 words
A light emitting diode according to claim 28 wherein said substrate is a single crystal.
Claim 44
Dependent Claim
28 words
A light emitting diode according to claim 40 wherein said substrate has a polytype of silicon carbide selected from the group consisting of 3C, 4H, 6H, and 15R.
Claim 45
Dependent Claim
105 words
A light emitting diode that emits light in the blue region of the visible spectrum with increased brightness and efficiency, said light emitting diode comprising: an n-type silicon carbide substrate; an n-type layer of silicon carbide on said n-type substrate; a p-type layer of silicon carbide on said n-type layer and defining a light emitting p-n junction between said p-type layer and said n-type layer; and a degenerate junction on said p-type layer, said degenerate junction being formed of a p-type portion and an n-type portion of silicon carbide, with said p-type portion of said degenerate junction being adjacent said p-type layer of silicon carbide.
Claim 46
Dependent Claim
105 words
A light emitting diode that emits light in the blue region of the visible spectrum with increased brightness and efficiency, said light emitting diode comprising: an n-type silicon carbide substrate; an n-type layer of silicon carbide on said n-type substrate; a p-type layer of silicon carbide on said n-type layer and defining a light emitting p-n junction between said p-type layer and said n-type layer; and a degenerate junction on said p-type layer, said degenerate junction being formed of a p-type portion and an n-type portion of silicon carbide, with said p-type portion of said degenerate junction being adjacent said p-type layer of silicon carbide.
Claim 47
Dependent Claim
49 words
A light emitting diode according to claim 42 wherein said doping in said p-type portion and said n-type portion in said degenerate junction is sufficiently heavy to substantially eliminate the barrier between the p-type portion and the n-type portion of the silicon carbide from which the portions are formed.
Claim 48
Dependent Claim
30 words
A light emitting diode according to claim 42 and further comprising an ohmic contact to said n-type substrate and an ohmic contact to said n-type portion in said degenerate junction.
Claim 49
Dependent Claim
35 words
A light emitting diode according to claim 42 wherein said p-type layer and said n-type layer in said degenerate junction are thin enough to substantially avoid absorption of light emitted from said light emitting junction.
Claim 50
Dependent Claim
15 words
A light emitting diode according to claim 42 wherein said substrate is a single crystal.
Claim 51
Dependent Claim
28 words
A light emitting diode according to claim 46 wherein said substrate has a polytype of silicon carbide selected from the group consisting of 3C, 4H, 6H, and 15R.
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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) | 1997-08-15 | 1998-02-14 | 1998-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-15 | 2002-02-14 | 2002-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-15 | 2006-02-14 | 2006-08-16 | $7700.00 | Window Closed / Lapsed |