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

• US 20060284537A1
• Filed: 08/28/2006
• Published: 12/21/2006
• Est. Priority Date: 03/24/2003
• Status: Active Grant

• Current Assignee: Zhidan L. Tolt
• Original Assignee: Zhidan L. Tolt
• Inventors: TOLT, Zhidan L.
• Granted Patent: US 7,521,851 B2
• Time in Patent Office: Days
• US Class Current: 313/306
• 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

1. An electron source comprising:

a substrate;

a cathode disposed over the substrate, the cathode being operable to provide a source of electrons;

an emitter layer disposed over the cathode and formed from a composition of an embedding material and one or a plurality of nano-structures embedded therein, said composition including interfaces between said nano-structures and said embedding material, the emitter layer having a surface at which ends of the nano-structures are truncated, the ends of the nano-structures and the interfaces between said nano-structures and the embedding material being exposed to emit electrons;

an insulator disposed over the emitter layer, the insulator having one or a plurality of apertures for exposing the ends of the nano-structure and the interface between the ends of the nano-structures and the embedding material; and

a gate electrode disposed over the insulator and having one or a plurality of apertures that are aligned with the apertures in the insulator, the gate electrode being operable to control the emission of electrons through the apertures from the exposed nano-structures;

wherein the nano-structures include nano-wire, nano-tube, nano-plane, nano-fiber, nano-cone, and non-diamond nano-particles.

2. An electron source as recited in claim 1,

wherein a vacuum is present in the apertures of the gate electrode and the insulator;

and

wherein an electric field is present in the vacuum between the exposed ends of the nano-structures in the surface of the emitter layer and the gate electrode, the electric field having an intensity that is increased over its vacuum intensity by the presence of the embedding material in the emitter layer.

3. An electron source as recited in claim 1, wherein the exposed ends of the nano-structures are at substantially the same distance from the gate electrode.

4. An electron source as recited in claim 1, wherein the embedding material is composed of a single material.

5. An electron source as recited in claim 1, wherein the embedding material is composed of multiple different materials.

6. An electron source as recited in claim 1, wherein the nano-structure is grown in alignment and with controlled spacing between nano-structures.

7. An electron source as recited in claim 1, wherein the nano-structures are grown randomly.

8. An electron source as recited in claim 1, wherein the nano-structures are prefabricated.

9. An electron source as recited in claim 1, wherein the exposed end of the nano-structure is slightly recessed from the surface of the emitter layer.

10. An electron source as recited in claim 1, wherein the surface of the emitter layer is treated to induce atomic bonding to the ends of the truncated nano-structures.

11. An electron source as recited in claim 1, wherein the nano-structures are conductive and the embedding material is an insulating material.

12. An electron source as recited in claim 11, wherein the insulating material that is selected from a group of materials consisting of:

ferroelectric materials, oxides, nitrides, carbides, diamond-like carbon, un-doped semiconductors, glasses, organically modified glasses, insulating ceramics and composites, and cured organic resins.

13. An electron source as recited in claim 11, wherein the conductive nano-structures are selected from a group of materials consisting of:

non-diamond carbon, doped-semiconductor, refractory metals and alloys, and conductive ceramics.

14. An electron source as recited in claim 13, wherein the non-diamond carbon includes carbon nano-tube, carbon nano-fiber, carbon nano-cone, carbon nano-particle and carbon nano-plane.

15. An electron source as recited in claim 11, wherein the conductive nano-structures are formed from an insulating core and a conductive shell.

16. An electron source as recited in claim 15, wherein the insulating core is a wide band gap semiconductor that includes AIN, AIGaN, BN, SiC, diamond, GaN.

17. An electron source as recited in claim 15, wherein the conductive nano-structures are a composite structure having alternating insulating and conductive layers.

18. An electron source as recited in claim 11, wherein the conductive nano-structures are grown directly on the substrate.

19. An electron source as recited in claim 18, wherein the conductive nano-structures are grown randomly.

20. An electron source as recited in claim 18, wherein the conductive nano-structures are grown with alignment and controlled spacing.

21. An electron source as recited in claim 1, wherein the embedding material is conductive and nano-structures are insulators.

22. An electron source as recited in claim 21, wherein the insulator nano-structures are grown on the substrate with alignment and controlled spacing between nano-structures.

23. An electron source as recited in claim 21, wherein the insulator nano-structures are grown randomly on the substrate.

24. An electron source as recited in claim 21, wherein the insulator nano-structures are pre-fabricated and deposited on the substrate by printing, spin coating, extrusion coating, dipping, and doctor blade.

25. An electron source as recited in claim 21, wherein the insulator nano-structures are selected from a group consisting of:

non-diamond wide band gap semiconductors, oxides, carbides, nitrides and semiconductors.

26. An electron source as recited in claim 25, wherein the non-diamond wide-band semiconductors include, BN, GaN, AIN, AIGaN, GaAs, SiC, ZnO.

27. An electron source as recited in claim 21, wherein the nano-structures are formed from a conductive core and an insulating shell.

28. An electron source as recited in claim 21, wherein the conductive embedding material is selected from the group consisting of:

conductive ceramics, conductive composites, metals, metal alloys, doped semiconductors, and conductive polymers.

29. An electron source as recited in claim 28, wherein the conductive composites include carbon and silver pastes.

30. An electron source as is recited is claim 1,

wherein the cathode electron is configured as rows of substantially parallel strips, each cathode strip for providing an independent source of electrons;

wherein the gate electrode is configured as columns of substantially parallel strips, each column strip intersecting with the rows of cathode strips at intersection patches and having one or a plurality of apertures at each intersection patch, wherein each gate electrode is configured to control the emission of electrons through the apertures along the gate electrode; and

wherein activation of a selected cathode strip and a selected gate electrode strip determine the intersection patches that emit electrons.

31. An electron source comprising:

a substrate;

a cathode disposed over the substrate and having side walls, the cathode being operable to provide a source of electrons;

an emitter layer disposed over a side wall of the cathode and formed from a composition of an embedding material and one or a plurality of nano-structures embedded therein, said composition including interfaces between said nano-structures and said embedding material, the emitter layer having a surface at which ends of the nanostructures are truncated, and the ends of the nano-structures and the interfaces between said nano-structures and the embedding material being exposed to emit electrons; and

a gate electrode disposed over the substrate and having a side wall spaced apart from and facing the emitter layer, the gate electrode being operable to control the emission of electrons from the exposed nano-structures of the facing emitter layer;

wherein the nano-structures include nano-wire, nano-tube, nano-plane, nano-fiber, nano-cone, and non-diamond nano-particles.

32. An electron source as recited in claim 31, wherein the nano-structures have ends that are slightly recessed from the surface of the emitter layer.

33. An electron source as recited in claim 32, wherein the nano-structures are insulator and the embedding material is conductive.

34. An electron source comprising:

a substrate;

electrode means, disposed over the substrate, for providing a source of electrons;

means, disposed over the source means, for emitting electrons provided by the source means into a vacuum, the emitting means including nano-structure emitting means for providing a flow of electrons and field-enhancement means for lowering a threshold field at which the emitting means emits electrons;

an insulator disposed over the emitting means; and

gating means, disposed over the insulator, for controlling the flow electrons emitted by the emitting means.

35. An electron source as recited in claim 34, wherein the gating means and the insulator each include one or more apertures that expose the nano-structure emitting means to the vacuum.

36. An electron source as recited in claim 34, wherein the nano-structure emitting means is a conductive material and the field-enhancement means is an insulating material.

37. An electron source as recited in claim 34, wherein the nano-structure emitting means is an insulating material and the field-enhancement means is a conductive material.

38. An electron field emission composite comprising:

one or more nano-structures;

an embedding material in which the nano-structures are embedded, the embedding material having a surface at which ends of the embedded nano-structures are truncated, and including interfaces with the nano-structures, the ends of the nano-structures and the interface between the nano-structures and the embedding materials being exposed, said exposed ends of the nano-structures configured to emit electrons when under the influence of an electric field applied in a vacuum proximate to the exposed ends.

39. An electron field emission composite as recited in claim 38, wherein the intensity of the applied electric field in vacuum is increased at the interface between the exposed tip of nano-structures and the embedding material by the presence of the embedding material.

40. An electron field emission composite as recited in claim 38, wherein the nano-structures are grown on a substrate.

41. An electron field emission composite recited in claim 40, wherein the nano-structures are grown in alignment and with controlled spacing between the nano-structures.

42. An electron field emission composite as recited in claim 38,

wherein the nano-structures are pre-fabricated;

and

wherein the embedding material is formed from a slurry.

43. An electron field emission composite as recited in claim 42,

wherein the nano-structures are insulators;

and

wherein the embedding material is a conducting material.

44. An electron field emission composite as recited in claim 43, wherein the insulator nano-structures are made of wide band gap semiconductors such as AIN, AIGaN, BN, SiC, and GaN.

45. An electron field emission composite as recited in claim 42, wherein the slurry forms from a conducting composite including carbon and silver pastes.

46. An electron field emission composite as recited in claim 42, wherein the pre-fabricated nano-structure is formed from non-diamond carbon.

47. An electron field emission composite as recited in claim 46, wherein the carbon includes carbon nanotube, carbon nanofiber, carbon nanocone, carbon nanoplane and carbon nanoparticle.

48. An electron field emission composite as recited in claim 38, wherein the nano-structures are slightly recessed from the surface of the emitter layer.