Field emission electron source

• US 6,057,637 A
• Filed: 06/27/1997
• Issued: 05/02/2000
• Est. Priority Date: 09/13/1996
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Cohen, Marvin Lou, Zettl, Alexander Karlwalter
• Primary Examiner(s): Patel, Ashok
• Application Number:
  US08/884,450
• Time in Patent Office: 1,040 Days
• Field of Search: 313/309, 313/336, 313/351, 313/310, 313/495, 313/496, 313/497, 495/60, 428/367, 428/408, 428/336, 428/323, 428/327, 428/366, 428/398, 428/402
• US Class Current: 313/310
• 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 2201/30403 characterised by the emitter shape
• CPC Class Codes: H01J 2201/30469 Carbon nanotubes (CNTs)
• CPC Class Codes: Y10S 977/939 Electron emitter, e.g. spindt emitter tip coated with nanoparticles
• CPC Class Codes: Y10T 428/2916 including boron or compound thereof [not as steel]
• CPC Class Codes: Y10T 428/2918 including free carbon or carbide or therewith [not as steel]
• CPC Class Codes: Y10T 428/2975 Tubular or cellular

Abstract

A novel field emitter material, field emission electron source, and commercially feasible fabrication method is described. The inventive field emission electron source produces reliable electron currents of up to 400 mA/cm² at 200 volts. The emitter is robust and the current it produces is not sensitive to variability of vacuum or the distance between the emitter tip and the cathode. The novel emitter has a sharp turn-on near 100 volts.

Claims

1. An electric field emitter material comprising,

a) a volume of binder;

and

b) a volume of B_X C_Y N_Z nanotubes suspended in the binder, where x, y, and z are numbers that indicate the relative ratios boron, carbon, and nitrogen.

2. The field emitter material of claim 1 wherein the volume of binder is between about 0.01 and about 10 times the volume of nanotubes.

3. The field emitter material of claim 1 wherein the volume of binder is between about 0.03 and about 3 times the volume of nanotubes.

4. The field emitter material of claim 1 wherein the volume of binder is about equal to the volume of nanotubes.

5. The field emitter material of claim 1 wherein the binder is electrically conducting.

6. The field emitter material of claim 1 wherein the binder is electrically non-conducting.

7. The field emitter material of claim 5 wherein the binder is chosen from the group consisting of epoxy, teflon, cyanoacrylate, polyethylene, ceramics, soft metals, and low melting point metals.

8. The field emitter material of claim 6 wherein the binder is chosen from the group consisting of epoxy, teflon, cyanoacrylate, polyethylene, ceramics, soft metals, and low melting point metals.

9. The field emitter material of claim 1 wherein the B_X C_Y N_Z nanotubes are electrically conducting when measured at about one volt.

10. The field emitter material of claim 1 wherein the B_X C_Y N_Z nanotubes are semimetallic when measured at about one volt.

11. The field emitter material of claim 1 wherein the B_X C_Y N_Z nanotubes are semiconducting when measured at about one volt.

12. The field emitter material of claim 1 wherein the B_X C_Y N_Z nanotubes are electrically insulating when measured at about one volt.

13. The field emitter material of claim 1 wherein the B_X C_Y N_Z nanotubes comprise a mixture of tubes comprising having electrical characteristics chosen from the group consisting of electrically conducting, semimetallic, semiconducting, and insulating.

14. The field emitter material of claim 1 wherein individual B_X C_Y N_Z nanotubes have two or more regions characterized by electrical properties chosen from the group consisting of electrically conducting, semimetallic, semiconducting, and insulating.

15. The electric field emitter material of claim 1 having metal deposited on it to form a pattern.

16. The electric field emitter material of claim 1 having inactive regions resulting from ion bombardment.

17. The electric field emitter material of claim 1 deposited through a mask onto a surface.

18. The electric field emitter material of claim 1 wherein the B_X C_Y N_Z nanotubes have X and Z=0 and Y-1.

19. An electric field emitter material comprising, B_X C_Y N_Z nanotubes bound to one another in a matrix, where x, y, and z are numbers that indicate the relative ratios boron, carbon, and nitrogen.

20. The field emitter material of claim 19 wherein the B_X C_Y N_Z nanotubes are chemically polymerized to one another.

21. A field emission electron source comprising,

a) a volume of binder;

b) a volume of B_X C_Y N_Z nanotubes suspended in the binder, where x, y, and z are numbers that indicate the relative ratios of boron, carbon, and nitrogen; and

c) at least one electrode attached to the binder matrix.

22. The field emission electron source of claim 21 having an electron emission area between about 1 and μ

² about 1 m².

23. The field emission electron source of claim 21 having an electron emission area between about 10 μ

² and about 100 cm².

24. The field emission electron source of claim 21 having an electron emission area between about 50 μ

² and about 10 cm².

25. The electric field emitter material of claim 21 wherein the B_X C_Y N_Z nanotubes have X and Z=0 and Y=1.