# US 5,703,435 A · Diamond film flat field emission cathode > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,435 A - Document ID: US5703435A - Status: Granted - Kind: A - Application number: 08/653,729 - Filed: 1996-05-23 - Granted: 1997-12-30 - Earliest claimed: 1992-03-16 - Assignees: Microelectronics and Computer Technology Corporation - Inventors: Nalin Kumar; Chenggang Xie - Web page: https://patentgrep.com/patent/US5703435A ## CPC - H01J 63/06: Lamps with luminescent screen excited by the ray or stream - H01J 1/304: Field-emissive cathodes - H01J 1/3042: {microengineered, e.g. Spindt-type} - H01J 9/027: {of thin film cathodes} - H01J 31/127: {using large area or array sources, i.e. essentially a source for each pixel group} - H01J 61/0677: {characterised by the electron emissive material} - H01J 63/00: Cathode-ray or electron-stream lamps - H01J 2201/304: Field emission cathodes - H01J 2201/30426: Coatings on the emitter surface, e.g. with low work function materials - H01J 2201/30457: Diamond - H01J 2329/00: Electron emission display panels, e.g. field emission display panels - H01J 2329/8625: Spacing members - Y10T 428/292: In coating or impregnation - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## 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 ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 2) The cathode as recited in claim 2, wherein said emission sites at said emission surface are relatively flat. ### Claim 4 (depends on 2) The cathode as recited in claim 2, wherein said sites have at least two different electron affinities. ### Claim 5 (depends on 1) The cathode as recited in claim 1, further comprising a means for applying said electric field to said field emission cathode. ### Claim 6 (depends on 1) The cathode as recited in claim 1, wherein said emission surface is greater than 20.569.6 square nanometers in area. ### Claim 7 (depends on 1) The cathode as recited in claim 1, wherein electrons are emitted from a vicinity of a boundary between said graphite and diamond crystallites. ### Claim 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. ### Claim 9 (depends on 8) The cathode as recited in claim 8, wherein said amorphic diamond comprises a plurality of SP.sup.2 crystallites and SP.sup.3 crystallites. ### Claim 10 (depends on 9) The cathode as recited in claim 9, wherein electrons are emitted from a vicinity of a boundary between the SP.sup.2 and SP.sup.3 crystallites. ### Claim 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. ### Claim 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. ### Claim 13 (depends on 12) 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. ### Claim 14 (depends on 12) 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. ### Claim 15 (depends on 12) 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. ### Claim 16 (depends on 12) The cathode structure as recited in claim 12, wherein some of said low effective work function material is amorphic diamond. ### Claim 17 (depends on 111) The cathode structure as recited in claim 111, wherein said amorphic diamond comprises SP.sup.2 and SP.sup.3 crystallites. ### Claim 18 (depends on 17) The cathode structure as recited in claim 17, wherein electrons are emitted from a vicinity of a boundary between said SP.sup.2 and SP.sup.3 crystallites. ### Claim 19 (depends on 18) The cathode structure as recited in claim 18, wherein said SP.sup.2 and SP.sup.3 crystallites comprise a mixture of graphite and diamond crystallites.