US3947716A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Field emission tip and process for making same
Assignee: United States Department of the Army
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Filing: 1973-08-27
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Granted: 1976-03-30
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Expires: 1993-08-27
Abstract
Abstract A field emission tip on which a metal adsorbate has been selectively deposited, and a method by which it may be manufactured. In a vacuum, a clean field emission tip is subjected to heating pulses in the presence of an electrostatic field to create thermal field buildup of a selected plane. Emission patterns from the selected plane are observed, and the process of heating the tip within the electrostatic field is repeated until emission is observed from the desired plane. The adsorbate is then evaporated onto the tip. The tip constructed by this process is selectively faceted, with the emitting planar surface having a reduced work function and the non-emitting planar surfaces having an increased work function. A metal adsorbate deposited on the tip so prepared results in a field emitter tip having substantially improved emission characteristics.
Inventors
- 👤 Donald L. Fraser, Jr.
- 👤 Bruce Perger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:44
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/02; H01J9/022; H01J9/025
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
74 words
A field emission tip comprising: a base material of a single crystal metal having an emitting planar surface and a plurality of non-emitting planar surfaces, said emitting surface having a reduced work function due to misalignment of the lattice atoms of said crystal metal, said non-emitting surfaces having an increased work function due to realignment of the lattice atoms of said crystal metal, and a monolayer of metal adsorbate atoms on said emitting surface.
Claim 2
Dependent Claim
74 words
A field emission tip comprising: a base material of a single crystal metal having an emitting planar surface and a plurality of non-emitting planar surfaces, said emitting surface having a reduced work function due to misalignment of the lattice atoms of said crystal metal, said non-emitting surfaces having an increased work function due to realignment of the lattice atoms of said crystal metal, and a monolayer of metal adsorbate atoms on said emitting surface.
Claim 3
Dependent Claim
11 words
The tip of claim 1 wherein said crystal metal is tungsten.
Claim 4
Dependent Claim
14 words
The tip of claim 2 wherein said emitting surface is along the (100) plane.
Claim 5
Dependent Claim
90 words
A process for the selective deposition of a metal adsorbate onto a field emission tip of a single crystal metal comprising the steps of: placing said tip in a suitable vacuum; flashing said tip until said tip becomes clean; creating an electrostatic field around said tip; flashing said tip in the presence of said electrostatic field, thereby creating surface migration of atoms of said single crystal metal along said tip until said tip surface is composed of faceted planes, and depositing a monolayer of metal adsorbate atoms onto said tip.
Claim 6
Dependent Claim
90 words
A process for the selective deposition of a metal adsorbate onto a field emission tip of a single crystal metal comprising the steps of: placing said tip in a suitable vacuum; flashing said tip until said tip becomes clean; creating an electrostatic field around said tip; flashing said tip in the presence of said electrostatic field, thereby creating surface migration of atoms of said single crystal metal along said tip until said tip surface is composed of faceted planes, and depositing a monolayer of metal adsorbate atoms onto said tip.
Claim 7
Dependent Claim
33 words
The process of claim 1 wherein flashing said tip in the presence of an electrostatic field includes producing an emitting plane and a plurality of non-emitting planes on the surface of said tip.
Claim 8
Dependent Claim
29 words
The process of claim 5 wherein flashing said tip in the presence of an electrostatic field includes reducing the work function of the emitting planar surface of said tip.
Claim 9
Dependent Claim
29 words
The process of claim 6 wherein flashing said tip in the presence of an electrostatic field includes increasing the work function of the non-emitting planar surfaces of said tip.
References Cited (Backward Citations)
US3374386A
Cited
US3817592A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-30 | 1979-09-29 | 1980-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-30 | 1983-09-29 | 1984-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-30 | 1987-09-29 | 1988-03-30 | $7700.00 | Window Closed / Lapsed |