US4286373A
Expired / Lapsed
US
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Method of making negative electron affinity photocathode
Assignee: United States Department of the Army
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Filing: 1980-01-08
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Granted: 1981-09-01
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Expires: 2000-01-08
Abstract
Abstract A method of making transmission mode glass-sealed negative electron affinity (NEA) gallium arsenide (GaAs) photocathodes, utilizing germanium (Ge) as the seed crystal and multilayers of GaAs and gallium aluminum arsenide (GaAlAs) grown by metal alkyl-hydride vapor-phase epitaxy. The GaAs serves as the photoemitting layer and the GaAlAs serves as the passivating layer. The Ge, GaAs,GaAlAs combination is sealed to a glass support substrate which serves as the input window for the device. Finally, the Ge is removed and the GaAs is activated.
Inventors
- 👤 William A. Gutierrez
- 👤 Herbert L. Wilson
- 👤 Edward M. Yee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:14
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/20; H01J9/233; H01J1/00; H01J1/02; H01J1/34; H01J2201/00; H01J2201/34; H01J2201/342; H01J2201/3421; H01J2201/3423
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
186 words
A method of making a glass-sealed transmission mode gallium arsenide photocathode comprising the steps of: (a) preparing a germanium seed crystal for epitaxial growth; (b) epitaxially growing a p-doped gallium arsenide photoemitting layer onto the prepared germanium crystal using the metal alkyl-hydride vapor-phase process; (c) epitaxially growing a p-doped gallium aluminum arsenide passivating layer onto said photoemitting layer using the metal alkyl-hydride vapor-phase process; (d) depositing a suitable antireflection or interface layer onto said passivating layer; (e) fusion bonding the antireflection or interface layer surface of the structure composed of seed crystal, photoemitting layer, passivating layer, and antireflection or interface layer to a glass faceplate that serves as the input window of the device; (f) preferentially etching away the exposed germanium seed crystal to expose the photoemitting layer; (g) applying ohmic contact to the periphery of said photoemitting layer for effecting electrical contact to the photocathode; (h) applying a suitable glass/air antireflection coating on the exposed photon input side of the glass window; and (i) activating the photoemitting layer by heat cleaning in vacuum and applying monolayer amounts of cesium and oxygen to the photoemitting layer.
Claim 2
Independent Claim
186 words
A method of making a glass-sealed transmission mode gallium arsenide photocathode comprising the steps of: (a) preparing a germanium seed crystal for epitaxial growth; (b) epitaxially growing a p-doped gallium arsenide photoemitting layer onto the prepared germanium crystal using the metal alkyl-hydride vapor-phase process; (c) epitaxially growing a p-doped gallium aluminum arsenide passivating layer onto said photoemitting layer using the metal alkyl-hydride vapor-phase process; (d) depositing a suitable antireflection or interface layer onto said passivating layer; (e) fusion bonding the antireflection or interface layer surface of the structure composed of seed crystal, photoemitting layer, passivating layer, and antireflection or interface layer to a glass faceplate that serves as the input window of the device; (f) preferentially etching away the exposed germanium seed crystal to expose the photoemitting layer; (g) applying ohmic contact to the periphery of said photoemitting layer for effecting electrical contact to the photocathode; (h) applying a suitable glass/air antireflection coating on the exposed photon input side of the glass window; and (i) activating the photoemitting layer by heat cleaning in vacuum and applying monolayer amounts of cesium and oxygen to the photoemitting layer.
Claim 3
Dependent Claim
26 words
The method of claim 1 wherein the composition of the gallium arsenide photoemitting layer is modified by the incorporation of indium to form gallium indium arsenide.
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) | 1984-08-31 | 1985-03-02 | 1985-09-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-31 | 1989-03-02 | 1989-09-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-31 | 1993-03-02 | 1993-09-01 | $7700.00 | Window Closed / Lapsed |