US4686761A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabrication of low crosstalk photodiode array
Assignee: United States Department of the Army
•
Filing: 1986-10-31
•
Granted: 1987-08-18
•
Expires: 2006-10-31
Abstract
Abstract A photodiode array structure and method of fabrication is provided. The ay is fabricated on a substrate as a multilayer structure with a novel combination of different type layers and then separated into optically independent diodes by delineation of the diodes. A novel array with heterojunction diodes for far-infrared is specifically disclosed.
Inventors
- 👤 Michael Hacskaylo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 00:37
CPC Classifications
H; H10; H10F; H10F39/00; H10F39/80; H10F39/802; H10F39/011; H10F39/028; H10F39/10; H10F39/12; H10F39/18; H10F39/184
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
182 words
The method of forming an array of pixel photodiodes for a selected band of radiation comprising the steps of: forming a crystalline substrate with a lattice structure compatible with the semiconductor materials used in said photodiodes; epitaxially depositing on a substrate a base contact layer of semiconducting material transparent to said of radiation and doped to provide high conductivity through majority carriers of a first polarity; epitaxially depositing on all but a small surface portion of said base contact layer a photo-current-generating layer of semiconducting material highly absorptive to said band of radiation and doped to provide medium conductivity through majority carriers of said first polarity; epitaxially depositing on said photo-current-generating layer a contact cap layer transparent to said band of radiation doped to provide medium conductivity through majority carriers opposite in polarity to said first polarity; removing small groove portions of said cap layer and all underlying portions of said photo-current-generating layer whereby these layers are divided into electro-optically isolated islands electrically interconnected through said base contact layer; and forming a passivation coating over all the exposed surfaces of said layers.
Claim 2
Independent Claim
182 words
The method of forming an array of pixel photodiodes for a selected band of radiation comprising the steps of: forming a crystalline substrate with a lattice structure compatible with the semiconductor materials used in said photodiodes; epitaxially depositing on a substrate a base contact layer of semiconducting material transparent to said of radiation and doped to provide high conductivity through majority carriers of a first polarity; epitaxially depositing on all but a small surface portion of said base contact layer a photo-current-generating layer of semiconducting material highly absorptive to said band of radiation and doped to provide medium conductivity through majority carriers of said first polarity; epitaxially depositing on said photo-current-generating layer a contact cap layer transparent to said band of radiation doped to provide medium conductivity through majority carriers opposite in polarity to said first polarity; removing small groove portions of said cap layer and all underlying portions of said photo-current-generating layer whereby these layers are divided into electro-optically isolated islands electrically interconnected through said base contact layer; and forming a passivation coating over all the exposed surfaces of said layers.
Claim 3
Dependent Claim
25 words
The method according to claim 1 wherein said step of removing includes: milling a series of narrow straight line grooves extending entirely across said layers.
Claim 4
Dependent Claim
30 words
The method according to claim 1 wherein said step of removing further includes the step of: removing only a small amount of the underlying portions of said base contact layer.
Claim 5
Dependent Claim
36 words
The method according to claim 1 further comprising the step of: depositing a metal contact on said small surface portion and on the cap layer of each of said islands, said contacts extending through said coating.
Claim 6
Dependent Claim
67 words
The method according to claim 1 further including the steps of: forming said crystalline substrate from a material transparent to radiation in said selected band; depositing a continuous layer of highly conductive metal over the exposed broad surface of said cap layer prior to removing said small portions; and removing the portions of said metal layer which overlay said small portions when said small portions are removed.
Claim 7
Dependent Claim
32 words
The method according to claim 5 wherein the step of forming a crystalline substrate includes the step of: forming said crystalline substrate from a material transparent to radiation in said selected band.
References Cited (Backward Citations)
US3880633A
Cited
US4197141A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-08-17 | 1991-02-16 | 1991-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-17 | 1995-02-16 | 1995-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-17 | 1999-02-16 | 1999-08-18 | $7700.00 | Window Closed / Lapsed |