US5661074A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High brightness electroluminescent device emitting in the green to ultraviolet spectrum and method of making the same
Assignee: Wolfspeed Inc
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Filing: 1995-05-24
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Granted: 1997-08-26
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Expires: 2015-05-24
Abstract
Abstract A green-blue to ultraviolet light-emitting optical device, e.g. a green-blue to ultraviolet emitting laser or a green-blue to ultraviolet emitting diode, comprising a green-blue to ultraviolet light emitting gallium nitride material on a base structure including a silicon carbide substrate, which preferably consists of 2H-SiC, 4H-SiC, or a-axis oriented 6H-SiC. The carrier mobility and the transparency of the silicon carbide substrate are optimized by the selection of orientation and polytype, thus enhancing device performance. The light-emitting diodes may incorporate a structural modification to increase the light output comprising a dielectric Bragg mirror beneath the LED structure, made of alternating layers of AlN, GaN, InN or their alloys. Methods for making such light-emitting diodes are provided, including a technique for defining individual devices by mesa etching which avoids possible damage to the active area during dicing.
Inventors
- 👤 Michael A. Tischler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:18
CPC Classifications
H; H10; H10H; H10H20/00; H10H20/80; H10H20/81; H10H20/822; H10H20/824; H10H20/825; H10H20/01; H10H20/011; H10H20/013; H10H20/0133; H10H20/01335; H10H20/814; H10H20/8142
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
107 words
A method of making a green-blue to ultraviolet light-emitting diode comprising forming a green-blue to ultraviolet light emitting material selected from the group consisting of: GaN; MGaN; and MM'GaN wherein: M is a metal which is compatible with Ga and N in the composition MGaN and the composition MGaN is stable at 25° C. and one atmosphere pressure conditions, and M' is a compatible metal providing quaternary compounds of the formula M 1-x-y M' y Ga x N, wherein x and y range from 0 to 1, on a base structure comprising a SiC substrate selected from the group consisting of 2H--SiC, 4H--SiC and a-axis oriented 6H--SiC.
Claim 2
Independent Claim
107 words
A method of making a green-blue to ultraviolet light-emitting diode comprising forming a green-blue to ultraviolet light emitting material selected from the group consisting of: GaN; MGaN; and MM'GaN wherein: M is a metal which is compatible with Ga and N in the composition MGaN and the composition MGaN is stable at 25° C. and one atmosphere pressure conditions, and M' is a compatible metal providing quaternary compounds of the formula M 1-x-y M' y Ga x N, wherein x and y range from 0 to 1, on a base structure comprising a SiC substrate selected from the group consisting of 2H--SiC, 4H--SiC and a-axis oriented 6H--SiC.
Claim 3
Dependent Claim
34 words
A method according to claim 1, wherein said base structure comprises at least one mesa on a top surface thereof, with said green-blue to ultraviolet light emitting material deposited on at least one mesa.
Claim 4
Dependent Claim
30 words
A method according to claim 2, wherein said at least one mesa on said base structure includes a main mesa surface having an equivalent diameter of less than 350 micrometers.
Claim 5
Dependent Claim
30 words
A method according to claim 2, wherein said at least one mesa on said base structure includes a main mesa surface having an equivalent diameter of less than 200 micrometers.
Claim 6
Dependent Claim
40 words
A method according to claim 2, wherein said at least one mesa is formed on a top surface on said base structure by etching a masked precursor base structure to a predetermined depth to yield said at least one mesa.
Claim 7
Dependent Claim
61 words
A method according to claim 1, wherein at least one mesa is formed on a top surface on said base structure after deposition of said green-blue to ultraviolet light emitting material on said base structure by etching of said deposited green-blue to ultraviolet light emitting material and underlying base structure to a predetermined depth to yield said at least one mesa.
Claim 8
Dependent Claim
53 words
A method according to claim 2, wherein said mesa structure formation comprises patterning said base structure with a metal mask defining said mesa structure, etching said patterned base structure to a predetermined depth, removing said metal mask, and depositing said green-blue to ultraviolet light emitting material on upper surfaces of said mesa structure.
Claim 9
Dependent Claim
20 words
A method according to claim 1, wherein the light-emitting green-blue to ultraviolet light emitting material includes a quantum well region.
Claim 10
Dependent Claim
26 words
A method according to claim 1, further comprising forming a Bragg mirror layer between the SiC substrate and the light-emitting green-blue to ultraviolet light emitting material.
Claim 11
Dependent Claim
19 words
A method according to claim 9, wherein the dielectric Bragg mirror comprises of green-blue to ultraviolet light emitting material.
Claim 12
Dependent Claim
31 words
A method according to claim 1, wherein the base structure comprises a buffer layer on said SiC substrate, between said SiC substrate and said light-emitting green-blue to ultraviolet light emitting material.
Claim 13
Dependent Claim
20 words
A method according to claim 11, wherein said buffer layer comprises a strained layer green-blue to ultraviolet light emitting superlattice.
Claim 14
Dependent Claim
26 words
A method according to claim 1, wherein the green-blue to ultraviolet light emitting material is selected from the group consisting of: GaN, AlGaN, InGaN, and AllnGaN.
Claim 15
Dependent Claim
26 words
A method according to claim 1, wherein the green-blue to ultraviolet light emitting material is selected from the group consisting of: GaN, AlGaN, InGaN, and AllnGaN.
Claim 16
Dependent Claim
16 words
A method according to claim 1, wherein the green-blue to ultraviolet light emitting material is GaN.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-08-25 | 2001-02-24 | 2001-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-25 | 2005-02-24 | 2005-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-25 | 2009-02-24 | 2009-08-26 | $7700.00 | Window Closed / Lapsed |