Patent US4772924A successfully refreshed from Google Patents.
US4772924A
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Device having strain induced region of altered bandgap
Assignee: Agere Systems LLC
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Filing: 1987-11-25
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Granted: 1988-09-20
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Expires: 2007-11-25
Abstract
Abstract A strained layer superlattice comprising Ge x Si 1-x layers interleaved with Si layers is an excellent photodetector at infrared wavelengths due to the large shift in bandgap caused by the strain in the superlattice.
Inventors
- 👤 John C. Bean
- 👤 David V. Lang
- 👤 Thomas P. Pearsall
- 👤 Roosevelt People
- 👤 Henryk Temkin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:02
CPC Classifications
B; B82; B82Y; B82Y20/00; H; H10; H10F; H10F30/00; H10F30/20; H10F30/21; H10F30/22; H10F30/225; H10F30/2255; H10F77/00; H10F77/10; H10F77/14; H10F77/146; H10F77/1465
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
85 words
A device comprising a substrate and disposed thereon a first cladding layer, an interleaved region of alternating first and second compositions comprising Ge x Si 1-x and Ge y Si 1-y , respectively, x greater than y and less than or equal to 1.0, having different lattice constants and a lattice mismatch, said mismatch being accommodated by strain thereby changing the bandgap from that of the bulk compositions and at least one of said x and y being selected to yield the strain induced bandgap.
Claim 2
Independent Claim
85 words
A device comprising a substrate and disposed thereon a first cladding layer, an interleaved region of alternating first and second compositions comprising Ge x Si 1-x and Ge y Si 1-y , respectively, x greater than y and less than or equal to 1.0, having different lattice constants and a lattice mismatch, said mismatch being accommodated by strain thereby changing the bandgap from that of the bulk compositions and at least one of said x and y being selected to yield the strain induced bandgap.
Claim 3
Dependent Claim
28 words
A device as recited in claim 1 further comprising a second cladding layer on the side of said interleaved region opposite to that of said first cladding layer.
Claim 4
Dependent Claim
19 words
A device as recited in claim 2 in which said first and second clading layers have opposite conductivity types.
Claim 5
Dependent Claim
20 words
A device as recited in claim 3 in which x and y are essentially constant in said strained layer region.
Claim 6
Dependent Claim
17 words
A device as recited in claim 4 in which said first and second cladding layers comprise silicon.
Claim 7
Dependent Claim
27 words
A device as recited in claim 5 further comprising a third layer of silicon having intrinsic conductivity and being between said second layer and said interleaved region.
Claim 8
Dependent Claim
29 words
A device as recited in claim 6 further comprising a fourth layer of silicon having a first conductivity type and being between said third layer and said interleaved region.
Claim 9
Dependent Claim
15 words
A device as recited in claim 7 in which said first conductivity type is n-type.
Claim 10
Dependent Claim
17 words
A device as recited in claim 5 in which x is between approximately 0.4 and approximately 0.6.
Claim 11
Dependent Claim
25 words
A device as recited in claim 1 in which said substrate comprising Si having an orientation selected from the group consisting of (100) and (110).
Claim 12
Independent Claim
66 words
A device comprising a substrate and disposed thereon a first layer comprising Ge x Si 1-x , x greater than 0.0 and less thanor equal to 1.0, having a different lattice constant than said substrate and a lattice mismatch, said mismatch being accommodated by strain thereby changing the bandgap from that of the bulk composition and said x being selected to yield the strain induced bandgap.
Claim 13
Independent Claim
66 words
A device comprising a substrate and disposed thereon a first layer comprising Ge x Si 1-x , x greater than 0.0 and less thanor equal to 1.0, having a different lattice constant than said substrate and a lattice mismatch, said mismatch being accommodated by strain thereby changing the bandgap from that of the bulk composition and said x being selected to yield the strain induced bandgap.
Claim 14
Dependent Claim
13 words
A device as recited in claim 11 in which said substrate comprises Si.
Claim 15
Dependent Claim
53 words
A device as recited in claim 12 further comprising a second layer comprising Ge y Si 1-y , y greater than or equal to 0.0 and less than 1.0, x not equal to y, sid second layer being disposed on said first layer, said first and second layers comprising a pair of layers.
Claim 16
Dependent Claim
20 words
A device as recited in claim 13 in which said first alyer and said second layers have opposite conductivity types.
Claim 17
Dependent Claim
21 words
A device as recited in claim 14 further comprising first and second electrical contacts to said substrate and second layer, respectively.
Claim 18
Dependent Claim
20 words
A device as recited in claim 15 in which said substrate and said second layer have the same conductivity types.
Claim 19
Dependent Claim
14 words
A device as recited in claim 16 in which y is less than x.
Claim 20
Dependent Claim
17 words
A device as recited in claim 17 further comprising a third electrical contact to said second layer.
Claim 21
Dependent Claim
18 words
A device as recited in claim 13 further comprising first and second electrical contacts to said second layer.
Claim 22
Dependent Claim
13 words
A device as recited in claim 13 comprising a plurality of said pairs.
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) | 1991-09-20 | 1992-03-21 | 1992-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-20 | 1996-03-21 | 1996-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-20 | 2000-03-21 | 2000-09-20 | $7700.00 | Window Closed / Lapsed |