US4099198A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photocathodes
Assignee: Teledyne UK Ltd
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Filing: 1976-05-14
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Granted: 1978-07-04
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Expires: 1996-05-14
Abstract
Abstract The input surface of a photocathode consisting of a membrane of p-type silicon is modified to improve it's sensitivity. The p-type concentration is locally increased and the surface is coated with silicon nitride.
Inventors
- 👤 Jonathan Ross Howorth
- 👤 Peter James Pool
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 08:38
CPC Classifications
H; H01; H01J; H01J29/00; H01J29/02; H01J29/10; H01J29/36; H01J29/38; H01J1/00; H01J1/54; H01J1/78; H01J9/00; H01J9/02; H01J9/12
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
72 words
A photocathode including a membrane of p-type silicon having a first major surface for receiving illumination and a second major surface from which electrons are emitted in response to the received illumination, said first major surface comprising a surface region having a p+ impurity concentration, an exterior surface layer of silicon nitride overlying said surface region, and a coating on said second major surface of a material which reduces its work function.
Claim 2
Dependent Claim
72 words
A photocathode including a membrane of p-type silicon having a first major surface for receiving illumination and a second major surface from which electrons are emitted in response to the received illumination, said first major surface comprising a surface region having a p+ impurity concentration, an exterior surface layer of silicon nitride overlying said surface region, and a coating on said second major surface of a material which reduces its work function.
Claim 3
Dependent Claim
24 words
A photocathode as claimed in claim 1 and wherein the first and second major surfaces are substantially parallel and of approximately the same size.
Claim 4
Dependent Claim
15 words
A photocathode as claimed in claim 1 and wherein the coating material is caesium oxide.
Claim 5
Dependent Claim
14 words
A photocathode as claimed in claim 1 and wherein the p-type impurity is boron.
Claim 6
Dependent Claim
28 words
A photocathode as claimed in claim 4 and wherein the p+ layer resuls from a diffusion process produced from a boron oxide vapour deposition at an elevated temperature.
Claim 7
Dependent Claim
18 words
A photocathode as claimed in claim 4 and wherein the p+ layer is produced by boron ion implantation.
Claim 8
Dependent Claim
46 words
A photocathode as claimed in claim 1 wherein the silicon nitride layer is laid down by vapour deposition, and is produced by passing a mixture of silane gas and ammonia gas in an inert carrier gas over the silicon membrane which is held at about 800°C.
Claim 9
Dependent Claim
64 words
A photocathode as defined in claim 4 wherein said surface region is rendered p+ by a boron concentration in the range 10 20 -10 10 22 per c.c. as compared with a boron concentration of the membrane in the order of 5 × 10 18 per c.c., said surface region having excess impurity concentration which is negligible at depths greater than 0.1 - 0.2μm.
Claim 10
Dependent Claim
20 words
A photocathode as defined in claim 8 wherein said membrane is of a thickness in the range 2 - 20μm.
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) | 1981-07-03 | 1982-01-02 | 1982-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-03 | 1986-01-02 | 1986-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-03 | 1990-01-02 | 1990-07-04 | $7700.00 | Window Closed / Lapsed |