Diamond film flat field emission cathode

• US 5,703,435 A
• Filed: 05/23/1996
• Issued: 12/30/1997
• Est. Priority Date: 03/16/1992
• Status: Expired due to Term

• Current Assignee: Applied Nanotech Holdings Incorporated (Nano Magic, Inc.)
• Original Assignee: Microelectronics and Computer Technology Corporation
• Inventors: Kumar, Nalin, Xie, Chenggang
• Primary Examiner(s): Patel, Ashok
• Application Number:
  US08/653,729
• Time in Patent Office: 586 Days
• Field of Search: 313/495, 313/497, 313/310, 313/461, 313/336, 313/351, 313/308, 313/309, 313/311, 313/346 R
• US Class Current: 313/495
• CPC Class Codes: H01J 1/304 Field-emissive cathodes
• CPC Class Codes: H01J 1/3042 microengineered, e.g. Spindt-type
• CPC Class Codes: H01J 2201/304 Field emission cathodes
• CPC Class Codes: H01J 2201/30426 Coatings on the emitter surface, e.g. with low work function materials
• CPC Class Codes: H01J 2201/30457 Diamond
• CPC Class Codes: H01J 2329/00 Electron emission display panels, e.g. field emission display panels
• CPC Class Codes: H01J 2329/8625 Spacing members
• CPC Class Codes: H01J 31/127 using large area or array sources, i.e. essentially a source for each pixel group
• CPC Class Codes: H01J 61/0677 characterised by the electron emissive material
• CPC Class Codes: H01J 63/00 Cathode-ray or electron-stream lamps
• CPC Class Codes: H01J 63/06 Lamps with luminescent screen excited by the ray or stream
• CPC Class Codes: H01J 9/027 of thin film cathodes
• CPC Class Codes: Y10T 428/292 In coating or impregnation

Abstract

A field emission cathode for use in flat panel displays is disclosed comprising a layer of conductive material and a layer of amorphic diamond film, functioning as a low effective work-function material, deposited over the conductive material to form emission sites. The emission sites each contain at least two sub-regions having differing electron affinities. Use of the cathode to form a computer screen is also disclosed along with the use of the cathode to form a fluorescent light source.

Claims

1. A field emission cathode, comprising:

a layer of conductive material; and

a layer of low work function material deposited over said conductive material, said low work function material having a relatively flat emission surface operable for emitting electrons in response to an applied electric field, wherein the low work function material comprises a mixture of graphite and diamond crystallites.

2. The cathode as recited in claim 1, wherein said low work function material having a relatively flat emission surface comprises a plurality of distributed localized electron emission sites.

3. The cathode as recited in claim 2, wherein said emission sites at said emission surface are relatively flat.

4. The cathode as recited in claim 2, wherein said sites have at least two different electron affinities.

5. The cathode as recited in claim 1, further comprising a means for applying said electric field to said field emission cathode.

6. The cathode as recited in claim 1, wherein said emission surface is greater than 20.569.6 square nanometers in area.

7. The cathode as recited in claim 1, wherein electrons are emitted from a vicinity of a boundary between said graphite and diamond crystallites.

8. A field emission cathode, comprising:

a layer of conductive material; and

a layer of work function material deposited over said conductive material, said low work function material having a relatively flat emission surface operable for emitting electrons in response to an applied electric field, wherein the low work function material is amorphic diamond.

9. The cathode as recited in claim 8, wherein said amorphic diamond comprises a plurality of SP² crystallites and SP³ crystallites.

10. The cathode as recited in claim 9, wherein electrons are emitted from a vicinity of a boundary between the SP² and SP³ crystallites.

11. A field emission cathode, comprising:

a layer of conductive material; and

a layer of low work function material deposited over said conductive material, said low work function material having a relatively flat emission surface operable for emitting electrons in response to an applied electric field, wherein some of said low effective work function material is amorphic diamond.

12. A field emission cathode structure, comprising:

a substrate; and

a layer of low work function material deposited over said substrate, said low work function material having a relatively flat emission surface, wherein said low work function material is amorphic diamond.

13. The cathode structure as recited in claim 12, wherein said low work function material is operable for emitting electrons in response to an applied electric field.

14. The cathode structure as recited in claim 12, wherein said low work function material having a relatively flat emission surface comprises a plurality of distributed localized electron emission sites.

15. The cathode structure as recited in claim 12, further comprising a means for applying an electric field to said field emission cathode so as to cause an emission of electrons from said flat emission surface.

16. The cathode structure as recited in claim 12, wherein some of said low effective work function material is amorphic diamond.

17. The cathode structure as recited in claim 111, wherein said amorphic diamond comprises SP² and SP³ crystallites.

18. The cathode structure as recited in claim 17, wherein electrons are emitted from a vicinity of a boundary between said SP² and SP³ crystallites.

19. The cathode structure as recited in claim 18, wherein said SP² and SP³ crystallites comprise a mixture of graphite and diamond crystallites.