US3978360A
Expired / Lapsed
US
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III-V photocathode with nitrogen doping for increased quantum efficiency
Assignee: National Aeronautics and Space Administration
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Filing: 1974-12-27
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Granted: 1976-08-31
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Expires: 1994-12-27
Abstract
Abstract An increase in the quantum efficiency of a III-V photocathode is achieved by doping its semiconductor material with an acceptor and nitrogen, a column-V isoelectronic element, that introduces a spatially localized energy level just below the conduction band similar to a donor level to which optical transitions can occur. This increases the absorption coefficient, α, without compensation of the acceptor dopant. A layer of a suitable I-V, I-VI or I-VII compound is included as an activation layer on the electron emission side to lower the work function of the photocathode.
Inventors
- 👤 with respect to an invention of Fletcher James C. Administrator of the National Aeronautics and Space Administration
- 👤 Lawrence William James
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 04:32
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/34; H01J2201/00; H01J2201/34; H01J2201/342; H01J2201/3421; H01J2201/3423
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
151 words
A photocathode comprised of a III-V direct band-gap semiconductor material selected from a group consisting of ternary and quaternary compounds that are comprised of a selected one of the following group of paired elements: Ga and As; Ga and Sb; In and As; In and Sb; and In and P, and a deposited layer of activation material forming an emissive surface on said semiconductor material wherein emitted electrons are produced by generation of electron-hole pairs upon absorption of photons by said semiconductor material, said semiconductor material being doped with an element functioning as an acceptor and with an isoelectronic element that introduces a spatially localized energy level just below the conduction band similar to a donor, thus increasing the optical absorption coefficient of said material without compensation of said acceptor dopant, said isoelectronic element being nitrogen and said acceptor dopant being selected from the group consisting of Zn, Mg and Cd.
Claim 2
Dependent Claim
151 words
A photocathode comprised of a III-V direct band-gap semiconductor material selected from a group consisting of ternary and quaternary compounds that are comprised of a selected one of the following group of paired elements: Ga and As; Ga and Sb; In and As; In and Sb; and In and P, and a deposited layer of activation material forming an emissive surface on said semiconductor material wherein emitted electrons are produced by generation of electron-hole pairs upon absorption of photons by said semiconductor material, said semiconductor material being doped with an element functioning as an acceptor and with an isoelectronic element that introduces a spatially localized energy level just below the conduction band similar to a donor, thus increasing the optical absorption coefficient of said material without compensation of said acceptor dopant, said isoelectronic element being nitrogen and said acceptor dopant being selected from the group consisting of Zn, Mg and Cd.
Claim 3
Dependent Claim
13 words
A photocathode as described in claim 1 wherein said semiconductor material is InAsP.
Claim 4
Dependent Claim
13 words
A photocathode as described in claim 1 wherein said semiconductor material is InGaAsP.
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) | 1979-08-31 | 1980-03-01 | 1980-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-31 | 1984-03-01 | 1984-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-31 | 1988-03-01 | 1988-08-31 | $7700.00 | Window Closed / Lapsed |