EP0150885A2
Expired / Lapsed
EP
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Semiconductor device for producing an electron beam
Assignee: Koninklijke Philips NV
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Filing: 1985-01-28
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Granted: —
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Expires: 2005-01-28
Abstract
Abstract In a semiconductor cathode, the electron-emitting part of a pn junction (5) is provided in the tip of a projecting portion (10) of the semiconductor surface (2) which is situated within an opening (8) in an insulating layer (7) on which an acceleration electrode (9) is disposed. Due to the increased electric field near the tip, a reduction of the work function (Schottky effect) is obtained. As a result, cathodes can be realized in which a material (14) reducing the work function, such as caesium, may be either dispensed with or replaced, if required, by another material, which causes lower work function, but is less volatile. The field strength remains so low that no field emission occurs and separate cathodes can be driven individually, which is favourable for applications in electron microscopy and electron lithography.
Inventors
- 👤 Karel Diederick Van Der Mast
- 👤 Arthur Marie Eugene Hoeberechts
- 👤 Gerardus Gegorius Petrus Van Gorkom
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 09:36
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/30; H01J1/308
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
93 words
A semiconductor device for producing an electron beam, having at least one cathode comprising a semiconductor body which is provided at a major surface with an electrically insulating layer with at least one opening, in which at least one acceleration electrode is provided on the insulating layer at the edge of the opening and the semiconductor body has a pn junction within the opening, characterized in that within the opening the semiconductor body has at least one projecting portion, whose cross-section, parallel to the major surface with distance from said major surface decreases.
Claim 2
Dependent Claim
93 words
A semiconductor device for producing an electron beam, having at least one cathode comprising a semiconductor body which is provided at a major surface with an electrically insulating layer with at least one opening, in which at least one acceleration electrode is provided on the insulating layer at the edge of the opening and the semiconductor body has a pn junction within the opening, characterized in that within the opening the semiconductor body has at least one projecting portion, whose cross-section, parallel to the major surface with distance from said major surface decreases.
Claim 3
Dependent Claim
21 words
A semiconductor device as claimed in Claim 1, characterized in that the projecting portion is substantially of conical or pyramidal shape.
Claim 4
Dependent Claim
24 words
A semiconductor device as claimed in Claim 1 or 2, characterized in that the projecting portion is rounded off at least near its apex.
Claim 5
Dependent Claim
26 words
A semiconductor device as claimed in Claim 3, characterized in that the rounded apex has a radius of curvature between 0.01 and 1 / M .
Claim 6
Dependent Claim
49 words
A semiconductor device as claimed in Claim 1, characterized in that the projecting portion is substantially strip-shaped near the major surface and in that, viewed in a cross-section at right angles to the longitudinal direction of the strip, the projecting portion is rounded off at least near its apex.
Claim 7
Dependent Claim
147 words
A semiconductor device as claimed in Claim 1, characterized in that the pn junction is located between an n-type surface region adjoining the surface of the semiconductor body within the opening and a p-type region, in which, when a voltage is applied in the reverse direction across the pn junction, electrons are generated in the semiconductor body, which emanate from the semiconductor body, and in which the pn junction has locally a lower breakdown voltage within the opening than the remaining part of the pn junction, the part with the lower breakdown voltage being separated from the surface by an n-type layer having such a thickness and doping that at the breakdown voltage the depletion zone of the pn junction does not extend as far as the surface, but remains separated therefrom by a surface layer, which is sufficiently thin to allow the generated electrons to pass.
Claim 8
Dependent Claim
38 words
A semiconductor device as claimed in any one of the preceding Claims, characterized in that with in the opening in the insulating layer the surface of the semiconductor body is coated with a material reducing the work function.
Claim 9
Dependent Claim
38 words
A camera tube provided with means for controlling an electron beam, which scans a charge image, characterized in that the electron beam is produced by a semiconductor device as claimed in any one or Claims 1 to 7.
Claim 10
Dependent Claim
39 words
A display arrangement provided with means for controlling an electron beam, which produces an image, characterized in that the electron beam is produced by means of a semiconductor device as claimed in any one of Claims 1 to 7.
Claim 11
Dependent Claim
50 words
A display arrangement as claimed in Claim 9, characterized in that this display arrangement comprises a fluorescent screen which is situated in vacuo at a distance of a few millimetres from the semiconductor device and in that the screen is activated by the electron beam originating from the semiconductor device.
References Cited (Backward Citations)
No citation records indexed.
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