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US3814968A Expired / Lapsed US ⏱️ 0.0 years remaining

Solid state radiation sensitive field electron emitter and methods of fabrication thereof

Assignee: ZF International UK Ltd
•
Filing: 1972-02-11
•
Granted: 1974-06-04
•
Expires: 1992-02-11
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Abstract

Abstract A solid state radiation sensitive field emitter cathode comprising a single crystal semiconductor member having a body portion with a uniform array of closely spaced and very sharp electron emitting projections from one surface in the form of needles or whisker like members. Electrons are emitted into vacuum when a planar-parallel positive anode is mounted in close proximity to the surface. The cathode is responsive to input radiation such as electrons or light directed onto the cathode in modifying the electron emission from the array of electron emitter projections. The method of manufacturing the cathode by providing a predetermined pattern or mosaic of islands of a material exhibiting a greater etch resistant property than the semiconductor material, on a wafer of a semiconductor material and then etching out between and beneath the islands to undercut to a point where the islands are supported by only a small whisker of the semiconductor material. Removal of the islands results in an electron emitter being exposed from beneath each island wherein carriers generated within the body portion and also carriers generated within the depletion regions of the tips diffuse to the electron emitter projections wherein establishment of a high electric field at the tips of the electron emitter projections results in electron emission primarily due to conduction band tunneling. The device provides about 106 emitting points of close proximity so as to effect photographic-like imaging.

Inventors

  • 👤 H Nathanson
  • 👤 R Thomas
  • 👤 J Guldberg

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-25 01:08
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/34; H01J1/30; H01J1/304; H01J31/00; H01J31/08; H01J31/26; H01J31/48; H01J31/49; H01J9/00; H01J9/02; H01J9/12; H01J2201/00; H01J2201/34; H01J2201/342; H01J2201/3421; H01J2201/3423; Y; Y10; Y10S; Y10S257/00; Y10S257/917

Claims Analysis

Total Claims: 12
Claim 1
Independent Claim 23 words
The device set forth in claim 1 in which said crystalline wafer is a silicon p-type material having a crystallographic orientation of (111).
Claim 2
Dependent Claim 22 words
The device set forth in claim 2, in which said silicon p-type material has a resistivity of greater than 0.1 ohm centimeter.
Claim 3
Dependent Claim 31 words
The structure set forth in claim 1 in which said wafer is provided with a P+ region on the opposite surface with respect to the surface from which the projections extend.
Claim 4
Dependent Claim 44 words
The structure set forth in claim 1 in which a passivating coating is provided on the opposite surface of said wafer with respect to said projection array and a passivation coating is provided on the projection array surface intermediate the tips of said projections.
Claim 5
Dependent Claim 30 words
The device set forth in claim 1 in which an electrically conductive coating is provided on the projection array surface of said wafer intermediate the emitting tips of said projections.
Claim 6
Dependent Claim 29 words
The device set forth in claim 1 in which said body member has thickness of about 25 micrometers and the height of said projection emitters is about 12 micrometers.
Claim 7
Dependent Claim 61 words
The device set forth in claim 1, in which said substrate body member has a thickness of from about 25 to 500 micrometers, and said non-growth projections extend from said substrate body member for a height of less than about 50 micrometers whereby charge carriers created throughout the substrate body member will diffuse out to and along said projections for emission.
Claim 8
Dependent Claim 23 words
The device as set forth in claim 1, wherein the density of said projections is about 1.5 X 103 projections per square millimeter.
Claim 9
Dependent Claim 13 words
The device specified in claim 1, wherein the semiconductive material is radiation sensitive.
Claim 10
Dependent Claim 28 words
The device set forth in claim 10, in which said radiation sensitive cold cathode field emitter device is utilized as a photocathode element in an image sensor device.
Claim 11
Dependent Claim 98 words
A radiation sensitive cold cathode field emitter device comprising a single crystalline wafer member of semiconductive material, said wafer member including a substrate body member having a thickness of from about 25 to 500 micrometers, and having an array of closely spaced substantially impurity free projections extending from the surface of said body member to a height of less than about 50 micrometers, with the minority carrier lifetime of the device being greater than about one microsecond, said substrate body member and said projections being crystallographically continuous and said projections having tip diameters of less than 1.0 micron.
Claim 12
Dependent Claim 22 words
The device specified in claim 12, wherein the closely spaced projections are spaced at about 1.5 X 103 projections per square millimeter.

References Cited (Backward Citations)

US3466485A Cited
US3665241A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1977-06-03 1977-12-03 1978-06-04 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1981-06-03 1981-12-03 1982-06-04 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1985-06-03 1985-12-03 1986-06-04 $7700.00 Window Closed / Lapsed

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