Patent US4760579A successfully refreshed from Google Patents.
US4760579A
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US
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Quantum well laser with charge carrier density enhancement
Assignee: The AT&T MVPD Group LLC
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Filing: 1986-07-01
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Granted: 1988-07-26
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Expires: 2006-07-01
Abstract
Abstract A resonant quantum well laser incorporates semiconductor barriers on one or both sides of the quantum well to increase the charge density within the quantum well. The composition of the injection layers can be tailored in a manner that the energies of the charge carriers in the injection layers are about that of a resonant energy level for that type of charge carrier in the quantum well. The barrier layers on one or both sides of the quantum well enhance the probability of the charge carrier being in the well for a longer time and travelling a longer distance, increasing the chance of scattering. The charge carriers, electrons or holes, can move from their respective injection layers into nearly identical energy levels within the quantum well, by tunneling through the thin barrier layers. The number of carriers which are available to transfer into the lasting energy level is increased, thereby increasing the efficiency of the laser and lowering its threshold current.
Inventors
- 👤 Joel N. Schulman
- 👤 Kavasseri V. Vaidyanathan
- 👤 Arthur L. Smirl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:47
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/30; H01S5/34; B; B82; B82Y; B82Y20/00; H01S5/3415; H01S5/3416
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
199 words
In an enhanced resonant quantum well laser wherein a quantum well region of at least one layer of semiconductor lasing material with a plurality of energy states for electrons is disposed between an electron injection layer and a hole injection layer, said electron injection-layer being the source of electrons to said quantum well region and said hole injection layer being the source of holes to said quantum well region, the improvement comprising: said electron injection layer supplying electrons to said quantum well at an energy level of about that of one of the energy levels for electrons in said quantum well region and said hole injection layer having a composition such that the bandgap of the hole injection layer is greater than that of the electron injection layer; and a barrier layer disposed between said quantum well and said electron injection layer, said barrier layer having a bandgap greater than that of the electron injection layer and being sufficiently thin to permit electrons to tunnel from said electron injection layer into said quantum well region, said barrier layer and the greater bandgap of said hole injection layer together increasing the probability of electrons being within said quantum well region.
Claim 2
Dependent Claim
199 words
In an enhanced resonant quantum well laser wherein a quantum well region of at least one layer of semiconductor lasing material with a plurality of energy states for electrons is disposed between an electron injection layer and a hole injection layer, said electron injection-layer being the source of electrons to said quantum well region and said hole injection layer being the source of holes to said quantum well region, the improvement comprising: said electron injection layer supplying electrons to said quantum well at an energy level of about that of one of the energy levels for electrons in said quantum well region and said hole injection layer having a composition such that the bandgap of the hole injection layer is greater than that of the electron injection layer; and a barrier layer disposed between said quantum well and said electron injection layer, said barrier layer having a bandgap greater than that of the electron injection layer and being sufficiently thin to permit electrons to tunnel from said electron injection layer into said quantum well region, said barrier layer and the greater bandgap of said hole injection layer together increasing the probability of electrons being within said quantum well region.
Claim 3
Dependent Claim
17 words
The improvement according to claim 1 wherein said barrier layer is less than about 40 Å thick.
Claim 4
Dependent Claim
21 words
The improvement of claim 1 wherein said barrier layer is in the range of about 10 to 20 Å in thickness.
Claim 5
Dependent Claim
14 words
The improvement according to claim 1 wherein said semiconductor lasing material is gallium arsenide.
Claim 6
Dependent Claim
17 words
The improvement according to claim 1 wherein the barrier layer is of an aluminum gallium arsenide alloy.
Claim 7
Dependent Claim
18 words
The improvement according to claim 1 wherein said electron injection layer is of an aluminum gallium arsenide alloy.
Claim 8
Dependent Claim
20 words
The improvement of claim 1 wherein said quantum well region comprises a plurality of alternating layers of two semiconductor materials.
Claim 9
Dependent Claim
35 words
The improvement according to claim 1 wherein the conduction band minimum of said electron injection layer is from about 0 to 0.4 electron volts beyond the quantum well region lasing energy level of the electrons.
Claim 10
Dependent Claim
57 words
The improvement according to claim 1 further comprising a further barrier layer disposed between said quantum region and said hole injection layer, said further barrier layer having a bandgap greater than that of said hole injection layer and being sufficiently thin to permit the holes to tunnel from said hole injection layer into said quantum well region.
Claim 11
Dependent Claim
21 words
The improvement according to claim 9 wherein said barrier layer and said further barrier layer are of different compositions and thicknesses.
Claim 12
Dependent Claim
18 words
The improvement according to claim 7 wherein said further barrier layer is less than about 40 Å thick.
Claim 13
Dependent Claim
22 words
The improvement according to claim 9 wherein said further barrier layer is in the range of about 10 to 20 Å thick.
Claim 14
Dependent Claim
263 words
In an enhanced resonant quantum well laser wherein a quantum well region of at least one layer of a semiconductor lasing material with a plurality of energy levels for electrons and a plurality of energy levels for holes is disposed between an electron injection layer and a hole injection layer, said electron injection layer being the source of electrons to said quantum well region and said hole injection layer being the source of holes to said quantum well region, the improvement comprising: said electron injection layer supplying electrons to said quantum well region at about the energy of one of the plurality of energy levels for the electrons in the quantum well region, and said hole injection layer plying holes at about the energy of one of the plurality of energy levels for the holes in said quantum well region; a first barrier layer disposed between and contacting said quantum well region and said electron injection layer, said first barrier layer having a bandgap greater than that of the electron injection layer and being sufficiently thin to permit electrons to tunnel from said electron injection layer into said quantum well region; and a second barrier layer disposed between and contacting said quantum well region and said hole injection layer, said second barrier layer having a bandgap greater than that of the hole injection layer and being sufficiently thin to permit holes to tunnel from said electron injection layer into said quantum well region, said first and second barrier layers increasing the probability of electrons and holes being in the said quantum well region.
Claim 15
Dependent Claim
263 words
In an enhanced resonant quantum well laser wherein a quantum well region of at least one layer of a semiconductor lasing material with a plurality of energy levels for electrons and a plurality of energy levels for holes is disposed between an electron injection layer and a hole injection layer, said electron injection layer being the source of electrons to said quantum well region and said hole injection layer being the source of holes to said quantum well region, the improvement comprising: said electron injection layer supplying electrons to said quantum well region at about the energy of one of the plurality of energy levels for the electrons in the quantum well region, and said hole injection layer plying holes at about the energy of one of the plurality of energy levels for the holes in said quantum well region; a first barrier layer disposed between and contacting said quantum well region and said electron injection layer, said first barrier layer having a bandgap greater than that of the electron injection layer and being sufficiently thin to permit electrons to tunnel from said electron injection layer into said quantum well region; and a second barrier layer disposed between and contacting said quantum well region and said hole injection layer, said second barrier layer having a bandgap greater than that of the hole injection layer and being sufficiently thin to permit holes to tunnel from said electron injection layer into said quantum well region, said first and second barrier layers increasing the probability of electrons and holes being in the said quantum well region.
Claim 16
Dependent Claim
18 words
The improvement according to claim 13 wherein said first barrier layer is less than about 40 Å thick.
Claim 17
Dependent Claim
17 words
The improvement according to claim 13 wherein said second barrier is less than about 40 Å thick.
Claim 18
Dependent Claim
212 words
In an enhanced resonant quantum well laser wherein a quantum well region of at least one layer of a semiconductor lasing material with a plurality of energy levels for electrons is disposed between an electron injection layer and a hole injection layer, said electron injection layer being the source of electrons to said quantum well and said hole injection layer being the source of holes to said quantum well, the improvement comprising: said electron injection layer being made of Al x Ga 1-x As, x being a fractional number between 0 and 1, and said hole injection layer being made of Al y Ga 1--y As, y being a fractional number between 0 and 1, wherein x is such that the energy of the electrons in said electron injection layer is about that of one of the energy levels for electrons in said quantum well region; and a barrier layer between said quantum well and said electron injection layer and having a composition of Al m Ga 1-m As, m being a fractional number between 0 and 1, where m is greater than x and said barrier layer has a thickness of less than about 40 ÅA to permit electrons to tunnel from said electron injection layer into said quantum well region.
Claim 19
Dependent Claim
212 words
In an enhanced resonant quantum well laser wherein a quantum well region of at least one layer of a semiconductor lasing material with a plurality of energy levels for electrons is disposed between an electron injection layer and a hole injection layer, said electron injection layer being the source of electrons to said quantum well and said hole injection layer being the source of holes to said quantum well, the improvement comprising: said electron injection layer being made of Al x Ga 1-x As, x being a fractional number between 0 and 1, and said hole injection layer being made of Al y Ga 1--y As, y being a fractional number between 0 and 1, wherein x is such that the energy of the electrons in said electron injection layer is about that of one of the energy levels for electrons in said quantum well region; and a barrier layer between said quantum well and said electron injection layer and having a composition of Al m Ga 1-m As, m being a fractional number between 0 and 1, where m is greater than x and said barrier layer has a thickness of less than about 40 ÅA to permit electrons to tunnel from said electron injection layer into said quantum well region.
Claim 20
Dependent Claim
13 words
The improvement according to claim 16 wherein x is substantially equal to y.
Claim 21
Dependent Claim
12 words
The improvement according to claim 16 wherein y is greater than x.
Claim 22
Dependent Claim
46 words
The improvement according to claim 16 further comprising a further barrier layer between said quantum well and said hole injection layer, and having a composition of Al n Ga 1-n As, n being a fractional number between 0 and 1, wherein n is greater than y.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-07-26 | 1992-01-25 | 1992-07-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-07-26 | 1996-01-25 | 1996-07-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-07-26 | 2000-01-25 | 2000-07-26 | $7700.00 | Window Closed / Lapsed |