US5652474A
Expired / Lapsed
US
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Method of manufacturing cold cathodes
Assignee: BTG International Ltd
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Filing: 1993-08-04
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Granted: 1997-07-29
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Expires: 2013-08-04
Abstract
Abstract PCT No. PCT/GB93/01650 Sec. 371 Date Feb. 3, 1995 Sec. 102(e) Date Feb. 3, 1995 PCT Filed Aug. 4, 1993 PCT Pub. No. WO94/03916 PCT Pub. Date Feb. 17, 1994A cold cathode is formed by providing a body of semiconductor having a surface including at least one projection and subjecting the surface to anodic etching to produce thereon a porous layer.
Inventors
- 👤 Peter Richard Wilshaw
- 👤 Emily Boswell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:00
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/02; H01J9/022; H01J9/025; H01J2209/00; H01J2209/02; H01J2209/022; H01J2209/0223; H01J2209/0226
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
31 words
A method of making a cold cathode, by providing a body of a semiconductor having a surface including at least one projection, which method comprises subjecting the surface to anodic etching.
Claim 2
Independent Claim
31 words
A method of making a cold cathode, by providing a body of a semiconductor having a surface including at least one projection, which method comprises subjecting the surface to anodic etching.
Claim 3
Dependent Claim
32 words
A method as claimed in claim 1, wherein the body of semiconductor having a surface including at least one projection itself had cold cathode properties even before being subjected to anodic etching.
Claim 4
Dependent Claim
13 words
A method as claimed in claim 1, wherein the semiconductor is of silicon.
Claim 5
Dependent Claim
25 words
A method as claimed in claim 1, wherein the anodic etching is performed under conditions to form a porous surface layer on the semiconductor body.
Claim 6
Dependent Claim
26 words
A method as claimed in claim 1, wherein the anodic etching is performed by a partial electrochemical dissolution step, followed by a partial chemical dissolution step.
Claim 7
Dependent Claim
19 words
A method as claimed in claim 5 wherein both partial dissolution steps are performed in hydrofluoric acid based solutions.
Claim 8
Dependent Claim
27 words
A cold cathode comprising a body of a semiconductor having a surface including at least one projection and having a porous surface layer of semiconductor or metal.
Claim 9
Dependent Claim
27 words
A cold cathode comprising a body of a semiconductor having a surface including at least one projection and having a porous surface layer of semiconductor or metal.
Claim 10
Dependent Claim
34 words
A cold cathode as claimed in claim 7, wherein the body of semiconductor having a surface including at least one projection itself had cold cathode properties even before formation of the porous surface layer.
Claim 11
Dependent Claim
23 words
A cold cathode as claimed in claim 7, wherein the semiconductor body is of silicon and has a surface layer of porous silicon.
Claim 12
Dependent Claim
20 words
A cold cathode as claimed in claim 7, wherein the surface of the semiconductor body includes an array of projections.
Claim 13
Dependent Claim
33 words
A cold cathode comprising a body of a semiconductor having a surface including at least one projection and having a surface layer of semiconductor or metal which has been subjected to anodic etching.
Claim 14
Dependent Claim
33 words
A cold cathode comprising a body of a semiconductor having a surface including at least one projection and having a surface layer of semiconductor or metal which has been subjected to anodic etching.
Claim 15
Dependent Claim
34 words
A cold cathode as claimed in claim 11, wherein the body of semiconductor having a surface including at least one projection itself had cold cathode properties even before it was subjected to anodic etching.
Claim 16
Dependent Claim
15 words
A cold cathode as claimed in claim 11, wherein the semiconductor body is of silicon.
Claim 17
Dependent Claim
20 words
A cold cathode as claimed in claim 11, wherein the surface of the semiconductor body includes an array of projections.
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) | 2000-07-28 | 2001-01-27 | 2001-07-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-07-28 | 2005-01-27 | 2005-07-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-07-28 | 2009-01-27 | 2009-07-29 | $7700.00 | Window Closed / Lapsed |