ELECTRON EMITTING COMPOSITE BASED ON REGULATED NANO-STRUCTURES AND A COLD ELECTRON SOURCE USING THE COMPOSITE

• US 20070003472A1
• Filed: 08/28/2006
• Published: 01/04/2007
• Est. Priority Date: 03/24/2003
• Status: Abandoned Application

• Current Assignee: Zhidan Tolt
• Original Assignee: Zhidan Tolt
• Inventors: Tolt, Zhidan
• Application Number:
  US11/467,880
• Publication Number:
  US 20070003472A1
• Time in Patent Office: Days
• US Class Current: 423/447.300
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H01J 1/304 Field-emissive cathodes
• CPC Class Codes: H01J 2201/30469 Carbon nanotubes (CNTs)
• CPC Class Codes: H01J 3/022 with microengineered cathode, e.g. Spindt-type
• CPC Class Codes: H01J 9/025 of field emission cathodes

Abstract

A field emission electron source includes a substrate, a first conductive electrode terminated to provide electrons, an emitting composite layer for emitting electrons, and a second electrode insulated from the emitter layer and terminated to extract electrons through vacuum space. The emitting composite layer lies between and parallel to the said first and the second electrodes, and comprises nano-structures embedded in a solid matrix. One end of the nano-structures is truncated and exposed at the surface of the emitter layer so that both the length and the apex of the nano-structure are regulated and the exposed nano-tips are kept substantially the same distance from the gate electrode. The embedding material is chosen to form triple junctions with the exposed tip to further enhance the field.

Claims

19. A method of forming an electron emitting composite, the method comprising:

forming a composite from an embedding material and one or plurality of nano-structures embedded therein;

forming an emitter layer by polishing the composite to form a surface at which the ends of the nano-structures are truncated, and the ends of the nano-structure and the interfaces between the nano-structures and the embedding material are exposed;

wherein the presence of the embedding material increases the intensity of externally applied electrical field at the interface between the exposed ends of the nano-structures and the embedding material.

1. A method of fabricating an electron source, the method comprising:

providing a substrate;

depositing on the substrate a first conductive layer;

depositing on the first conductive layer an emitter layer composed of an embedding material and one or plurality of nano-structures embedded therein;

truncating and exposing the ends of the nano-structures and the interface between the nano-structures and the embedding material;

depositing an insulator over the polished surface of the emitter layer;

depositing second conductive layer over the insulator; and

removing portions of second conductive layer and insulator to form apertures therein and expose the ends of the nano-structures for emission.

2. A method as recited in claim 1, wherein depositing an emitter layer includes:

depositing on the first conductive layer a thin catalyst layer;

growing an array of from the catalyst; and

conformally depositing a material to embed the nano-structures, the embedding material and nano-structures forming the emitter layer with a surface at which ends of the nano-structures are to be exposed.

3. A method as recited in claim 2, where the grown nano-structures are in alignment and with controlled spacing between the nano-structures.

4. A method as recited in claim 1,

wherein the nano-structures conductive,

wherein the embedding material is an insulator.

5. A method as recited in claim 4, where the nano-structure include carbon nanotubes, carbon nanofibers, carbon nanocones, and carbon nanoplane,

6. A method as recited in claim 4, wherein the conductive nano-structure is formed from an insulator core and a conductive shell.

7. A method as recited in claim 6, where the insulator core is made of a wide band gap semiconductor including diamond, BN, AlN, GaN, AlGaN and SiC.

8. A method as recited in claim 4, wherein the embedding insulator is SiO₂.

9. A method as recited in claim 1,

wherein the nano-structures is a wide band gap semiconductor including AlN, GaN, AlGaN, BN, and SiC,

wherein the embedding material is a conductive material including refractory metals and alloys, conductive ceramics, conductive composite and doped semiconductors.

10. A method as recited in claim 1, wherein the nano-structures are further etched after truncation such that the nano-structures are slightly recessed from the surface of the emitter layer.

11. A method as recited in claim 1, wherein depositing the emitter layer includes:

dispersing pre-fabricated nano-structures in a slurry to form an uniform mixture;

depositing the uniform mixture on the first conductive layer;

drying the uniform mixture; and

heating at a high temperature to form the emitter layer with a surface at which ends of the nano-structures are to be exposed.

12. A method as recited in claim 1, wherein depositing the emitter layer includes:

dispersing pre-fabricated nano-structures in a precursor solution;

coating the first conductive layer with the solution; and

condensing the precursor solution to form the emitter layer with a surface at which ends of the nano-structures are to be exposed.

13. A method as recited in claim 1, wherein the truncation is performed by polishing.

14. A method as recited in claim 13, where the polishing is performed by chemical-mechanical planarization.

15. A method as recited in claim 1, further comprising the step of depositing and patterning an etch-stopper prior to truncating and exposing the ends of the nano-structures by polishing the surface of the emitter layer.

16. A method as recited in claim 1, further comprising the step of a surface treatment after truncating and exposing the ends of the nano-structures for enhanced field emission of the nano-structures.

17. A method as recited in claim 1,

wherein the embedding material is comprised of at least two layers;

and

further comprising;

depositing the first layer by vapor deposition; and

depositing the second layer by disposing a fluidic precursor onto the substrate and curing or condensing the precursor by heating or illumination.

18. A method as recited in claim 1, wherein the truncation is performed by a combination of lithography and chemical etch.

20. A method as recited in claim 19, wherein the composite is formed from growing one or more the nano-structures on a substrate and comformally depositing an embedding material to encapsulate the nano-structures.

21. A method as recited in claim 20, wherein the nano-structures are grown in alignment and with controlled spacing between the nano-structures.

22. A method as recited in claim 21, wherein the conductive nano-structures include carbon nanotube, carbon nano-fiber, carbon nano-cone, and carbon nano-plane.

23. A method as recited in claim 19, wherein the nano-structures have at least an insulator core and a conductive shell.

24. A method as recited in claim 19, wherein the nano-structure is an insulator, wherein the embedding material is conductive.

25. A method as recited in claim 24, wherein the insulator nano-structure is made of a wide band gap material including AlN, AlGaN, GaN, BN, and SiC.

26. A method as recited in claim 24, wherein the nano-structures have at least a conductive core and an insulator shell.

27. A method as recited in claim 24, wherein the conductive embedding material include the refractive metals and alloys, conductive ceramics, conductive composites, and doped semiconductors.

28. A method as recited in claim 19, wherein the embedding material is made of at least two different materials.

29. A method as recited in claim 19 further comprises of a step of etching back the nano-structures after polishing so that the nano-structures slightly recessed from the surface of the emitting layer.

30. A method as recited in claim 19, wherein forming the composite further comprising:

dispersing pre-fabricated nano-structures in a binder containing slurry to form a uniform mixture;

casting the mixture;

drying the cast;

heating the cast at high temperature to remove the binder.

31. A method as recited in claim 19, wherein the polishing is performed by chemical mechanical planarization.

21-1. A method as recited in claim 19, wherein the nano-structures are conductive,

wherein the embedding material is an insulator.