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US5874747A
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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: 1996-02-05
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Granted: 1999-02-23
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Expires: 2016-02-05
Abstract
Abstract PCT No. PCT/US96/01724 Sec. 371 Date Nov. 24, 1997 Sec. 102(e) Date Nov. 24, 1997 PCT Filed Feb. 5, 1996 PCT Pub. No. WO96/24167 PCT Pub. Date Aug. 8, 1996A green-blue to ultraviolet light emitting semiconductor laser having a top contact, a Bragg reflector, cladding layer, active layer, cladding layer, buffer, substrate, bottom contact and a passivation layer. The key aspect is a Ga*N material on a base structure comprising a SiC substrate selected from a group consisting of 2H-SiC, 4H-SiC and a-axis oriented 6H-SiC. Furthermore, the cladding layers have larger band gaps than the active layer and are complimentarily doped.
Inventors
- 👤 Joan Redwing
- 👤 Michael A. Tischler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:30
CPC Classifications
H; H10; H10H; H10H20/00; H10H20/80; H10H20/84; H10H20/01; H10H20/011; H10H20/013; H10H20/0133; H10H20/01335; H10H20/81; H10H20/822; H10H20/824; H10H20/825; H10H20/814; H10H20/8142
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
33 words
A semiconductor device or precursor thereof, comprising a layer of single crystal silicon carbide and a layer of single crystal gallium nitride, having a buffer layer therebetween comprising a compositionally graded Ga*N layer.
Claim 2
Dependent Claim
33 words
A semiconductor device or precursor thereof, comprising a layer of single crystal silicon carbide and a layer of single crystal gallium nitride, having a buffer layer therebetween comprising a compositionally graded Ga*N layer.
Claim 3
Dependent Claim
27 words
A semiconductor device or precursor thereof according to claim 1, wherein the silicon carbide comprises a polytype selected from the group consisting of 2H-SiC, 4H-SiC, and 6H-SiC.
Claim 4
Dependent Claim
85 words
A semiconductor device or precursor thereof according to claim 1, wherein said compositionally graded Ga*N layer comprise a compositionally graded Al x Ga 1-x N buffer layer between the gallium nitride and silicon carbide layers, wherein x can range from 0 to 1, and the buffer layer is compositionally graded from an interface of the the buffer layer with the silicon carbide layer at which x is 0, to an interface of the buffer layer with the gallium nitride layer at which x is 1.
Claim 5
Dependent Claim
30 words
A semiconductor device or precursor thereof, comprising a silicon carbide substrate and an epitaxial layer of gallium nitride, having a buffer layer therebetween comprising a compositionally graded (Al,Ga)N buffer layer.
Claim 6
Dependent Claim
30 words
A semiconductor device or precursor thereof, comprising a silicon carbide substrate and an epitaxial layer of gallium nitride, having a buffer layer therebetween comprising a compositionally graded (Al,Ga)N buffer layer.
Claim 7
Dependent Claim
38 words
A semiconductor device or precursor thereof according to claim 4, wherein said buffer layer comprises an AlGal-,N buffer layer where the Al composition (x) is graded from 1 at the buffer-SiC interface to 0 at the GaN-buffer interface.
Claim 8
Dependent Claim
24 words
A semiconductor device or precursor thereof according to claim 4, wherein the thickness of said buffer layer is from 200 Å to 5 μm.
Claim 9
Dependent Claim
24 words
A semiconductor device or precursor thereof according to claim 4, wherein the thickness of said buffer layer is from 500 Å to 1 μm.
Claim 10
Dependent Claim
51 words
A semiconductor device or precursor thereof, comprising a silicon carbide substrate and an epitaxial layer of gallium nitride, having a buffer material therebetween comprising an AlN buffer layer on the silicon carbide substrate, and a compositionally graded (Al,Ga)N buffer layer between the AlN buffer layer and the gallium nitride epitaxial layer.
Claim 11
Dependent Claim
51 words
A semiconductor device or precursor thereof, comprising a silicon carbide substrate and an epitaxial layer of gallium nitride, having a buffer material therebetween comprising an AlN buffer layer on the silicon carbide substrate, and a compositionally graded (Al,Ga)N buffer layer between the AlN buffer layer and the gallium nitride epitaxial layer.
Claim 12
Dependent Claim
25 words
A semiconductor device or precursor thereof according to claim 8, wherein the thickness of said AlN buffer layer is from 50 Å to 5 μm.
Claim 13
Dependent Claim
25 words
A semiconductor device or precursor thereof according to claim 8, wherein the thickness of said AlN buffer layer is from 100 Å to 1 μm.
Claim 14
Dependent Claim
56 words
A semiconductor device or precursor thereof, comprising a silicon carbide substrate and an epitaxial layer of gallium nitride, having a buffer material therebetween comprising a conductive buffer layer of the formula Al x Ga 1-x N wherein the buffer layer includes a lower Al composition layer that is doped to render it highly conductive in character.
Claim 15
Dependent Claim
56 words
A semiconductor device or precursor thereof, comprising a silicon carbide substrate and an epitaxial layer of gallium nitride, having a buffer material therebetween comprising a conductive buffer layer of the formula Al x Ga 1-x N wherein the buffer layer includes a lower Al composition layer that is doped to render it highly conductive in character.
Claim 16
Dependent Claim
21 words
A semiconductor device or precursor thereof according to claim 11, wherein x is in the range of from x=1 to x=0.3.
Claim 17
Dependent Claim
21 words
A semiconductor device or precursor thereof according to claim 11, wherein x is in the range of from x=0.7 to x=0.4.
Claim 18
Dependent Claim
42 words
A semiconductor device or precursor thereof according to claim 11, wherein the buffer material comprises an end composition adjacent said gallium nitride epitaxial layer, selected from the group consisting of GaN and a lower Al y Ga 1-y N composition, where y<x.
Claim 19
Dependent Claim
34 words
A semiconductor device or precursor thereof according to claim 14, wherein the buffer material comprises a s said end composition Al y Ga 1-y N and the gallium nitride epitaxial layer comprises (Al, Ga)N.
Claim 20
Dependent Claim
19 words
A semiconductor device or precursor thereof according to claim 11, wherein the conductive buffer layer is an n-type material.
Claim 21
Dependent Claim
19 words
A semiconductor device or precursor thereof according to claim 11, wherein the conductive buffer layer is a p-type material.
Claim 22
Dependent Claim
50 words
A semiconductor device or precursor thereof, comprising a silicon carbide substrate and an epitaxial layer of gallium nitride, having a buffer material therebetween comprising a buffer layer selected from the group consisting of (Al, Ga)N compositionally graded layers, (Al, In)N compositionally graded layers, and (Al, Ga, In)N compositionally graded layers.
Claim 23
Dependent Claim
50 words
A semiconductor device or precursor thereof, comprising a silicon carbide substrate and an epitaxial layer of gallium nitride, having a buffer material therebetween comprising a buffer layer selected from the group consisting of (Al, Ga)N compositionally graded layers, (Al, In)N compositionally graded layers, and (Al, Ga, In)N compositionally graded layers.
Claim 24
Dependent Claim
19 words
A semiconductor device or precursor thereof according to claim 18, wherein the epitaxial layer of gallium nitride contains In.
Claim 25
Dependent Claim
38 words
A semiconductor device or precursor thereof according to claim 19, wherein the epitaxial layer of gallium nitride comprises an epitaxial layer formed of material selected from the group consisting of (In, Ga)N, (In, Ga)N, and (Al, Ga, In)N.
Claim 26
Dependent Claim
48 words
A semiconductor device or precursor thereof according to claim 19, wherein the epitaxial layer of gallium nitride comprises In 0 .1 Ga 0 .9 N,and the buffer material includes AlN grading through (Al, Ga)N to GaN, and grading from GaN to In 0 .1 Ga 0 .9 N.
Claim 27
Dependent Claim
56 words
A semiconductor device or precursor thereof, comprising a SiC substrate element including a mesa-shaped portion having a Ga*N quantum well structure or other Ga*N s tructure formed thereon, where in t he mesa-shaped portion has an equivalent diameter in the range of from 50 to 300 μm, and a height of from 1 to 15 μm.
Claim 28
Dependent Claim
56 words
A semiconductor device or precursor thereof, comprising a SiC substrate element including a mesa-shaped portion having a Ga*N quantum well structure or other Ga*N s tructure formed thereon, where in t he mesa-shaped portion has an equivalent diameter in the range of from 50 to 300 μm, and a height of from 1 to 15 μm.
Claim 29
Dependent Claim
30 words
A semiconductor device or precursor thereof according to claim 22, wherein the SiC substrate comprise an SiC polytype selected from the group consisting of 2H-SiC, 4H-SiC, and a-axis oriented 6H-SiC.
Claim 30
Dependent Claim
39 words
A semiconductor device or precursor thereof according to claim 22, wherein said mesa-shaped portion has a quantum well structure thereon, and said quantum well structure includes a well having a well width of from 150 Å to 750 Å.
Claim 31
Independent Claim
182 words
A method for fabricating a light emitting diode comprising the steps of: a. forming an M x M' y M" 1-x-y N barrier layer on a conductive substrate, wherein M, M', and M" are metals compatible with nitrogen (N) in the composition M x M' y M" 1-x-y N, and the composition M x M' y M" 1-x-y N is stable at room temperatures and pressures; b. forming an M a M' b M" 1-a-b N active region on the M x M' y M" 1-x-y N barrier layer; c. forming an M c M' d M" 1-c-d N barrier layer on the M a M' b M" 1-a-b N active region; d. forming a heavily doped contact layer on the M c M' d M" 1-c-d N barrier layer; and e. forming a first contact on the heavily doped contact layer and a second contact on the substrate, wherein x, y, a, b, c, and d are numbers, each number having a magnitude between zero and one and wherein x+y, a+b, and c+d, each have a magnitude between zero and one.
Claim 32
Independent Claim
182 words
A method for fabricating a light emitting diode comprising the steps of: a. forming an M x M' y M" 1-x-y N barrier layer on a conductive substrate, wherein M, M', and M" are metals compatible with nitrogen (N) in the composition M x M' y M" 1-x-y N, and the composition M x M' y M" 1-x-y N is stable at room temperatures and pressures; b. forming an M a M' b M" 1-a-b N active region on the M x M' y M" 1-x-y N barrier layer; c. forming an M c M' d M" 1-c-d N barrier layer on the M a M' b M" 1-a-b N active region; d. forming a heavily doped contact layer on the M c M' d M" 1-c-d N barrier layer; and e. forming a first contact on the heavily doped contact layer and a second contact on the substrate, wherein x, y, a, b, c, and d are numbers, each number having a magnitude between zero and one and wherein x+y, a+b, and c+d, each have a magnitude between zero and one.
Claim 33
Dependent Claim
31 words
The method of claim 25 wherein the substrate is a selected polytype of silicon carbide (SiC) selected from a group of polytypes of SiC including 2H-SiC, 4H-SiC, and a-axis oriented 6H-SiC.
Claim 34
Dependent Claim
24 words
The method of claim 26 wherein the SiC substrate is oriented to have a high mobility axis aligned with the direction of electron current.
Claim 35
Independent Claim
179 words
A method for fabricating a light emitting diode comprising the steps of: a. forming a first barrier layer on a conductive substrate, the first barrier layer being a first selected composition; b. forming an active region of a second selected composition on the first barrier layer; C. forming a second barrier layer of a third selected composition on the active region; d. forming a heavily doped contact layer of a fourth selected composition on the second barrier layer; and e. forming a first contact on the heavily doped contact layer and a second contact on the substrate, wherein the first, second, third and fourth selected compositions are selected from a group of compositions M x M' y M" 1-x-y N, M a M' b M" 1-a-b N, M c M' d M" 1-c-d N and M e M' f M" 1-e-f N, respectively, wherein x, y, a, b, c, d, e, and f are numbers, each number having a magnitude between zero and one and wherein x+y, a+b, c+d, and e+f, each has a magnitude between zero and one.
Claim 36
Independent Claim
179 words
A method for fabricating a light emitting diode comprising the steps of: a. forming a first barrier layer on a conductive substrate, the first barrier layer being a first selected composition; b. forming an active region of a second selected composition on the first barrier layer; C. forming a second barrier layer of a third selected composition on the active region; d. forming a heavily doped contact layer of a fourth selected composition on the second barrier layer; and e. forming a first contact on the heavily doped contact layer and a second contact on the substrate, wherein the first, second, third and fourth selected compositions are selected from a group of compositions M x M' y M" 1-x-y N, M a M' b M" 1-a-b N, M c M' d M" 1-c-d N and M e M' f M" 1-e-f N, respectively, wherein x, y, a, b, c, d, e, and f are numbers, each number having a magnitude between zero and one and wherein x+y, a+b, c+d, and e+f, each has a magnitude between zero and one.
Claim 37
Dependent Claim
31 words
The method of claim 28 wherein the substrate is a selected polytype of silicon carbide (SC) selected from a group of polytypes of SC including 2H-SiC, 4H-SiC, and a-axis oriented 6H-SiC.
Claim 38
Independent Claim
207 words
The method for fabricating a light emitting diode with a Bragg mirror, the method comprising the steps of: a. forming a Bragg mirror including alternating layers of AlN, GaN, InN, or their alloys on a conductive substrate; b. forming an M x M' y M" 1-x-y N barrier layer on a conductive substrate, wherein M, M', and M" are metals compatible with nitrogen (N) in the composition M x M' y M" 1-x-y N, and the composition M x M' y M" 1-x-y N is stable at room temperatures and pressures; c. forming an M a M' b M" 1-a-b N active region on the M x M' y M" 1-x-y N barrier layer; d. forming an M c M' d M" 1-c-d N barrier layer on the M a M' b M" 1-a-b N active region; e. forming a heavily doped contact layer on the M c M' d M" 1-c-d N barrier layer; and f. forming a first contact on the heavily doped contact layer and a second contact on the substrate, wherein x, y, a, b, c, and d are numbers, each number having a magnitude between zero and one and wherein x+y, a+b, and c+d, each have a magnitude between zero and one.
Claim 39
Independent Claim
207 words
The method for fabricating a light emitting diode with a Bragg mirror, the method comprising the steps of: a. forming a Bragg mirror including alternating layers of AlN, GaN, InN, or their alloys on a conductive substrate; b. forming an M x M' y M" 1-x-y N barrier layer on a conductive substrate, wherein M, M', and M" are metals compatible with nitrogen (N) in the composition M x M' y M" 1-x-y N, and the composition M x M' y M" 1-x-y N is stable at room temperatures and pressures; c. forming an M a M' b M" 1-a-b N active region on the M x M' y M" 1-x-y N barrier layer; d. forming an M c M' d M" 1-c-d N barrier layer on the M a M' b M" 1-a-b N active region; e. forming a heavily doped contact layer on the M c M' d M" 1-c-d N barrier layer; and f. forming a first contact on the heavily doped contact layer and a second contact on the substrate, wherein x, y, a, b, c, and d are numbers, each number having a magnitude between zero and one and wherein x+y, a+b, and c+d, each have a magnitude between zero and one.
Claim 40
Dependent Claim
31 words
The method of claim 30 wherein the substrate is a selected polytype of silicon carbide (SiC), selected from a group of polytypes of SiC including 2H-SiC, 4H-SiC, and a-axis oriented 6H-SiC.
Claim 41
Independent Claim
112 words
The method for fabricating light emitting diodes (LEDs) comprising the steps of: a. forming a first barrier layer on a conductive substrate; b. forming an active region on the first barrier layer; C. forming a second barrier layer on the active region; d. forming a heavily doped contact layer on the second barrier layer; e. masking each LED device area; f. mesa etching trenches between the LED device areas and leaving the LEDs as mesas separated by the trenches; g. passivating sidewalls of the LEDs; h. forming a first contact on the heavily doped contact layer and a second contact on the substrate; and i. slicing the substrate only in the trenches.
Claim 42
Independent Claim
112 words
The method for fabricating light emitting diodes (LEDs) comprising the steps of: a. forming a first barrier layer on a conductive substrate; b. forming an active region on the first barrier layer; C. forming a second barrier layer on the active region; d. forming a heavily doped contact layer on the second barrier layer; e. masking each LED device area; f. mesa etching trenches between the LED device areas and leaving the LEDs as mesas separated by the trenches; g. passivating sidewalls of the LEDs; h. forming a first contact on the heavily doped contact layer and a second contact on the substrate; and i. slicing the substrate only in the trenches.
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