US3901745A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gallium arsenide photocathode
Assignee: International Standard Electric Corp
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Filing: 1974-01-30
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Granted: 1975-08-26
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Expires: 1994-01-30
Abstract
Abstract A gallium arsenide photocathode is formed from a substrate of gallium arsenide on which are grown a first thin gallium aluminum arsenide layer and a further thin active layer of gallium arsenide. A coating of wax is applied over the thin active GaAs layer and around the sides and peripheral edges of the structure. A central region of the GaAs substrate is then etched to expose the inner GaAlAs layer while leaving a supporting rim around the edges. The rim permits use of a thinner GaAlAs layer.
Inventors
- 👤 Martin Pion
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:33
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/34; H01J9/00; H01J9/02; H01J9/12; H01J2201/00; H01J2201/34; H01J2201/342; H01J2201/3421; H01J2201/3423; Y; Y10; Y10S; Y10S148/00; Y10S148/051; Y10S148/056; Y10S148/072; Y10S148/12; Y10S148/135
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
119 words
A METHOD OF MAKING A GAASA TRANSMISSION TYPE PHOTOCATHODE COMPRISING THE STEPS OF GROWING AN EPITAXIAL LAYER OF GAALAS UPON A GAAS SUBSTRATE, GROWING AN EPETAXIAL LAYER OF GAAS UPON THE LAYER OF GAALAS, COATING THE ENTIRE OUTER SURFACE OF THE GAAS EPITAXIAL LAYER WITH A LAYER OF WAX ENTENDING AROUND THE SIDES OF GAAS EPITAXIAL AND GAALAS EPITAXIAL LAYERS AND AROUND THE PERIPHERAL RIM PORTION ON THE OPPOSITE SURFACE OF THE GAAS SUBSTRATE SO THAT ONLY THE CENTRAL REGION OF THE SUBSTRATE IS EXPOSED, AND REMOVING THE EXPOSED CENTRAL REGION OF THE GAAS SUBSTRATE WITHOUT PENETRATING THROUGH EITHER OF THE EPITAXIAL LAYERS TO FORM AN APERTURED RIM OF GAAS SUPPORTING THE PERIPHERY OF THE GAALAS AND GAAS LAYERS.
Claim 2
Independent Claim
119 words
A METHOD OF MAKING A GAASA TRANSMISSION TYPE PHOTOCATHODE COMPRISING THE STEPS OF GROWING AN EPITAXIAL LAYER OF GAALAS UPON A GAAS SUBSTRATE, GROWING AN EPETAXIAL LAYER OF GAAS UPON THE LAYER OF GAALAS, COATING THE ENTIRE OUTER SURFACE OF THE GAAS EPITAXIAL LAYER WITH A LAYER OF WAX ENTENDING AROUND THE SIDES OF GAAS EPITAXIAL AND GAALAS EPITAXIAL LAYERS AND AROUND THE PERIPHERAL RIM PORTION ON THE OPPOSITE SURFACE OF THE GAAS SUBSTRATE SO THAT ONLY THE CENTRAL REGION OF THE SUBSTRATE IS EXPOSED, AND REMOVING THE EXPOSED CENTRAL REGION OF THE GAAS SUBSTRATE WITHOUT PENETRATING THROUGH EITHER OF THE EPITAXIAL LAYERS TO FORM AN APERTURED RIM OF GAAS SUPPORTING THE PERIPHERY OF THE GAALAS AND GAAS LAYERS.
Claim 3
Dependent Claim
17 words
The method of claim 1 including the step of attaching the wax-coated outer surface to a support.
Claim 4
Dependent Claim
24 words
The method as claimed in claim 2 wherein the central region of the GaAs substrate is removed by etching to expose the GaAlAs layer.
Claim 5
Dependent Claim
28 words
The method as claimed in claim 3 and including removing the layer of wax and caesiating at least a portion of the outer surface of the GaAs layer.
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) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |