Patent US4246590A successfully refreshed from Google Patents.
US4246590A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Restoration of high infrared sensitivity in extrinsic silicon detectors
Assignee: Northrop Grumman Corp
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Filing: 1979-01-22
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Granted: 1981-01-20
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Expires: 1999-01-22
Abstract
Abstract A method and apparatus for removing heavy metal impurities such as gold, silver, nickel and copper from a crystalline substrate is described incorporating a damaged crystalline layer which may be formed by excessive doping to trap or getter heavy metal impurities to enhance the majority carrier lifetime of the detector material. The invention overcomes the problem of degraded responsivity in radiant energy crystalline detectors after high temperature processing, in excess of 900° C., which permits surface contaminants such as gold, silver, nickel and copper to diffuse through the detector material raising the net donor density.
Inventors
- 👤 Richard N. Thomas
- 👤 Timothy T. Braggins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 08:47
CPC Classifications
H; H10; H10F; H10F71/00; H10F39/00; H10F39/10; H10F39/12; H10F39/15; H10F39/157; H10P; H10P36/00; H10P36/03; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02P; Y02P70/00; Y02P70/50; Y10; Y10S; Y10S257/00; Y10S257/928
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
146 words
A sensor for converting radiant energy into electrical signals comprising: a crystalline substrate having a first and second surface including means for passing radiant energy into said substrate, said substrate including doping atoms for generating electronic charge in response to the absorption of radiant energy and including impurity atoms of a first type which diffuse readily throughout the substrate at times said substrate is above 900° C., a first electrode formed in said first surface, a second electrode formed in said second surface, means for coupling a first voltage across said first and second electrodes to attract electronic charge to said first electrode, and a layer having a damaged crystalline lattice structure formed in said substrate to getter impurity atoms of said first type from said substrate at times when said substrate is above 900° C. to enhance the majority carrier lifetime of the substrate material.
Claim 2
Dependent Claim
146 words
A sensor for converting radiant energy into electrical signals comprising: a crystalline substrate having a first and second surface including means for passing radiant energy into said substrate, said substrate including doping atoms for generating electronic charge in response to the absorption of radiant energy and including impurity atoms of a first type which diffuse readily throughout the substrate at times said substrate is above 900° C., a first electrode formed in said first surface, a second electrode formed in said second surface, means for coupling a first voltage across said first and second electrodes to attract electronic charge to said first electrode, and a layer having a damaged crystalline lattice structure formed in said substrate to getter impurity atoms of said first type from said substrate at times when said substrate is above 900° C. to enhance the majority carrier lifetime of the substrate material.
Claim 3
Dependent Claim
34 words
The sensor of claim 1 wherein said layer is formed by diffusing a high conentration of impurity atoms of a second type in said crystalline substrate to alter and disrupt the crystalline lattice structure.
Claim 4
Dependent Claim
25 words
The sensor of claim 2 wherein said high concentration of impurity atoms of a second type is at least 10 19 atoms cm -3 .
Claim 5
Dependent Claim
18 words
The sensor of claim 2 wherein said layer is in the range from 0.7 to 1 micrometer thick.
Claim 6
Dependent Claim
26 words
The sensor of claim 2 wherein said crystalline substrate is silicon, said majority carriers are holes and said impurity atoms of a first type include gold.
Claim 7
Dependent Claim
26 words
The sensor of claim 2 wherein said crystalline substrate is silicon, said majority carriers are holes and said impurity atoms of a first type include silver.
Claim 8
Dependent Claim
21 words
The sensor of claim 2 wherein said layer is formed in part by raising its temperture to at least 900° C.
Claim 9
Dependent Claim
11 words
The sensor of claim 2 wherein said crystalline substrate is germanium.
Claim 10
Dependent Claim
14 words
The sensor of claim 2 wherein said crystalline substrate is an alloy of germanium.
Claim 11
Dependent Claim
14 words
The sensor of claim 2 wherein said crystalline substrate is an alloy of silicon.
Claim 12
Dependent Claim
17 words
The sensor of claim 1 wherein said layer is formed in said first surface of said substrate.
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) | 1984-01-20 | 1984-07-21 | 1985-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-20 | 1988-07-21 | 1989-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-20 | 1992-07-21 | 1993-01-20 | $7700.00 | Window Closed / Lapsed |