Patent US4894526A successfully refreshed from Google Patents.
US4894526A
Expired / Lapsed
US
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Infrared-radiation detector device
Assignee: Nokia Bell Labs
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Filing: 1987-09-15
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Granted: 1990-01-16
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Expires: 2007-09-15
Abstract
Abstract A narrow-bandwidth, high-speed infrared radiation detector is based on tunneling of photo-excited electrons out of quantum wells. Infrared radiation incident on a superlattice of doped quantum wells gives rise to intersubband resonance radiation which excites electrons from the ground state into an excited state. A photocurrent results from excited electrons tunneling out of quantum wells. Conveniently, Group III-V materials can be used in device manufacture. Preferably, quantum well potential barriers are shaped so as to facilitate resonant tunneling of photocurrents as compared with dark current. Preferred device operation is at elevated bias voltage, giving rise to enhancement of photocurrent by a quantum-well-avalanche effect.
Inventors
- 👤 Clyde G. Bethea
- 👤 Kwong-Kit Choi
- 👤 Barry F. Levine
- 👤 Roger J. Malik
- 👤 John F. Walker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 02:20
CPC Classifications
H; H10; H10F; H10F30/00; H10F30/20; H10F30/21; B; B82; B82Y; B82Y20/00; H10F77/00; H10F77/10; H10F77/14; H10F77/146
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
98 words
A device comprising an infrared-radiation detector, said detector comprising a substrate-supported heterostructure superlattice comprising semiconductor layers forming a plurality of quantum wells doped for one and the same conductivity type, at least one of said quantum wells having at least two confined states and having an adjoining first barrier which permits tunneling of photo-excited carriers out of said quantum well, subsequent transport of said carriers being at energies above the barrier-top energy of a second barrier, and contact means for electrically biasing said superlattice and for sensing an electrical signal in response to radiation incident on said superlattice.
Claim 2
Independent Claim
98 words
A device comprising an infrared-radiation detector, said detector comprising a substrate-supported heterostructure superlattice comprising semiconductor layers forming a plurality of quantum wells doped for one and the same conductivity type, at least one of said quantum wells having at least two confined states and having an adjoining first barrier which permits tunneling of photo-excited carriers out of said quantum well, subsequent transport of said carriers being at energies above the barrier-top energy of a second barrier, and contact means for electrically biasing said superlattice and for sensing an electrical signal in response to radiation incident on said superlattice.
Claim 3
Dependent Claim
14 words
The device of claim 1 in which said quantum wells have two confined states.
Claim 4
Dependent Claim
29 words
The device of claim 1 in which, in the presence of a bias field, at least a portion of said quantum wells forms an essentially linear sequence of energies.
Claim 5
Dependent Claim
31 words
The device of claim 1 in which, in the presence of a bias field, at least a portion of said quantum wells forms a sequence of energies having a parabolic component.
Claim 6
Dependent Claim
46 words
The device of claim 1 in which the energy level of a first state of a first quantum well is essentially equal to the energy level of a second state in a second quantum well, said second quantum well being adjacent to said first quantum well.
Claim 7
Dependent Claim
13 words
The device of claim 1 in which said semiconductor layers are compound-semiconductor layers.
Claim 8
Dependent Claim
15 words
The device of claim 6 in which said compound-semiconductor layers are Group III-V semiconductor layers.
Claim 9
Dependent Claim
21 words
The device of claim 7 in which said superlattice consists essentially of alternating layers of gallium arsenide and gallium aluminum arsenide.
Claim 10
Dependent Claim
22 words
The device of claim 7 in which said superlattice consists essentially of alternating layers of indium phosphide and indium gallium arsenide phosphide.
Claim 11
Dependent Claim
21 words
The device of claim 7 in which said superlattice consists essentially of alternating layers of gallium antimonide and aluminum gallium antimonide.
Claim 12
Dependent Claim
12 words
The device of claim 7 in which said quantum wells are n-doped.
Claim 13
Dependent Claim
11 words
The device of claim 7 in which said superlattice is modulation-doped.
Claim 14
Dependent Claim
12 words
The device of claim 1, said device comprising a plurality of photodetectors.
Claim 15
Dependent Claim
12 words
The device of claim 13, said plurality of photodetectors forming an array.
Claim 16
Dependent Claim
27 words
The device of claim 1, said quantum wells having potential barriers whose compositional profile is chosen to favor resonant tunneling of photocurrent as compared with dark current.
Claim 17
Dependent Claim
12 words
The device of claim 15, said barriers having a graded compositional profile.
Claim 18
Dependent Claim
12 words
The device of claim 16, grading of said profile being essentially linear.
Claim 19
Dependent Claim
12 words
The device of claim 16, grading of said profile being essentially parabolic.
Claim 20
Dependent Claim
12 words
The device of claim 16, grading of said profile being essentially M-shaped.
Claim 21
Dependent Claim
35 words
The device of claim 16, pairs of quantum wells being such that resonant tunneling is facilitated for photocurrent electrons by matching energy levels, and impeded for dark current electrons by lack of energy level matching.
Claim 22
Independent Claim
115 words
A method for detecting infrared radiation, said method comprising making said radiation incident on a substrate-supported heterostructure superlattice comprising semiconductor layers forming a plurality of quantum wells doped for one and and the same conductivity type, at least one of said quantum wells having at least two confined states and having an adjoining first barrier which permits tunneling of photo-excited carriers out of said quantum well, subsequent transport of said carriers being at energies above the barrier-top energy of a second barrier, electrically biasing said superlattice such that the voltage across said at least one quantum well is greater than the energy difference between said confined states, and sensing a current flowing through said superlattice.
Claim 23
Independent Claim
115 words
A method for detecting infrared radiation, said method comprising making said radiation incident on a substrate-supported heterostructure superlattice comprising semiconductor layers forming a plurality of quantum wells doped for one and and the same conductivity type, at least one of said quantum wells having at least two confined states and having an adjoining first barrier which permits tunneling of photo-excited carriers out of said quantum well, subsequent transport of said carriers being at energies above the barrier-top energy of a second barrier, electrically biasing said superlattice such that the voltage across said at least one quantum well is greater than the energy difference between said confined states, and sensing a current flowing through said superlattice.
Claim 24
Dependent Claim
18 words
The method of claim 21, said voltage being equal or approximately equal to 1.25 times said energy difference.
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) | 1993-01-15 | 1993-07-17 | 1994-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-15 | 1997-07-17 | 1998-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-15 | 2001-07-17 | 2002-01-16 | $7700.00 | Window Closed / Lapsed |