Methods for adjusting the conductivity range of a nanotube fabric layer

• US 8,941,094 B2
• Filed: 09/02/2010
• Issued: 01/27/2015
• Est. Priority Date: 09/02/2010
• Status: Active Grant

• Current Assignee: Nantero Incorporated
• Original Assignee: Nantero Incorporated
• Inventors: Cleavelin, C. Rinn, Rueckes, Thomas, Manning, H. Montgomery, Hamilton, Darlene, Gu, Feng
• Primary Examiner(s): Smoot, Stephen W
• Assistant Examiner(s): Chin, Edward
• Application Number:
  US12/874,501
• Publication Number:
  US 20120056149A1
• Time in Patent Office: 1,608 Days
• Field of Search: 257/9, 257/E45.002, 257/E21.159, 257/E21.041, 257/E23.09, 257/E29.054, 257/24, 438/600, 438/3, 438/514
• US Class Current: 257/24
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: H01B 1/24 the conductive material comprising carbon-silicon compounds, carbon or silicon
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H10K 30/821 comprising carbon nanotubes
• CPC Class Codes: H10K 71/211 by selective transformation of an existing layer
• CPC Class Codes: H10K 85/221 Carbon nanotubes
• CPC Class Codes: H10N 70/8845 Carbon or carbides
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

Methods for adjusting and/or limiting the conductivity range of a nanotube fabric layer are disclosed. In some aspects, the conductivity of a nanotube fabric layer is adjusted by functionalizing the nanotube elements within the fabric layer via wet chemistry techniques. In some aspects, the conductivity of a nanotube fabric layer is adjusted by functionalizing the nanotube elements within the fabric layer via plasma treatment. In some aspects, the conductivity of a nanotube fabric layer is adjusted by functionalizing the nanotube elements within the fabric layer via CVD treatment. In some aspects, the conductivity of a nanotube fabric layer is adjusted by functionalizing the nanotube elements within the fabric layer via an inert ion gas implant.

Claims

1. A method for adjusting the conductivity range of a nanotube fabric layer, comprising:

forming a nanotube fabric layer on a substrate, said nanotube fabric layer comprising a plurality of nanotube elements and having an electrical resistance, wherein said electrical resistance of said nanotube fabric layer is capable of being switched among a plurality of non-volatile resistive states responsive to an applied electrical stimulus, said plurality of non-volatile resistive states falling within a conductivity range characterized by a lower limit and an upper limit; and

functionalizing at least a portion of said plurality of nanotube elements within said nanotube fabric layer to adjust at least one of said lower limit and said upper limit of said conductivity range of the nanotube fabric.

2. The method of claim 1 wherein said step of functionalizing decreases said upper limit of said conductivity range.

3. The method of claim 1 wherein said step of functionalizing increases said lower limit of said conductivity range.

4. The method of claim 1 wherein said step of functionalizing increases said upper limit of said conductivity range.

5. The method of claim 1 wherein said step of functionalizing decreases said lower limit of said conductivity range.

6. The method of claim 1 wherein said step of functionalizing increases the uniformity of said conductivity range.

7. The method of claim 1 wherein said step of functionalizing introduces at least one irreversible defect within said nanotube fabric layer.

8. The method of claim 1 wherein said step of functionalizing introduces at least one switching site within said nanotube fabric layer.

9. The method of claim 1 wherein said step of functionalizing eliminates at least one switching site within said nanotube fabric layer.

10. The method of claim 1 wherein said step of functionalizing comprises dispersing a filler material over said nanotube fabric layer such that said filler material penetrates through at least a portion of said nanotube fabric layer.

11. The method of claim 10 wherein said filler material penetrates through substantially all of said nanotube fabric layer.

12. The method of claim 10 wherein said filler material is one selected from the group consisting of silicon dioxide, silica, and silicon nitride.

13. The method of claim 10 wherein dispersing said filler material comprises dispersing ions of an inert gas.

14. The method of claim 13 wherein said inert gas is one selected from the group consisting of helium, neon, argon, krypton, and xenon.

15. The method of claim 10 wherein dispersing said filler material comprises dispersing ions of a chemically reactive substance.

16. The method of claim 15 wherein said chemically reactive substance is one selected from the group consisting of nitrogen, fluorine, boron, phosphorous, arsenic, and antimony.

17. The method of claim 10 wherein dispersing said filler material comprises performing a chemical vapor deposition process.

18. The method of claim 17 wherein said chemical vapor deposition process is one of a low pressure chemical vapor deposition (LPCVD) process, an atmospheric chemical vapor deposition (APCVD) process, an atomic layer deposition chemical vapor deposition (ALD-CVD) process, a plasma enhanced chemical vapor deposition (PECVD) process, a high density plasma chemical vapor deposition (HDP-CVD) process, or a photochemical chemical vapor deposition process.

19. The method of claim 1 wherein said step of functionalizing comprises dispersing a gas over said nanotube fabric layer.

20. The method of claim 19 wherein said gas is one selected from the group consisting of nitrogen and argon.

21. The method of claim 1 wherein said step of functionalizing comprises implanting ions of an inert gas.

22. The method of claim 21 wherein said inert gas is selected from the group consisting of helium, neon, argon, krypton, and xenon.

23. The method of claim 1 wherein said step of functionalizing comprises implanting ions of a chemically reactive substance.

24. The method of claim 23 wherein said chemically reactive substance is an atomic substance selected from the group consisting of nitrogen, fluorine, boron, phosphorous, arsenic, and antimony.

25. The method of claim 23 wherein said chemically reactive substance is a molecular substance selected from the group consisting of N₂, BF₂, BH₃, PH₃, and AsH₃.

26. The method of claim 23 further comprising annealing said nanotube fabric layer subsequent to implanting said ions of a chemically reactive substance.

27. The method of claim 26 wherein said step of annealing activates chemical bonding between said plurality of nanotube elements and said chemically reactive substance.

28. The method of claim 1 wherein said step of functionalizing comprises introducing defects to at least one pre-selected region within said nanotube fabric layer.

29. The method of claim 28 wherein said at least one pre-selected region is electrically insulating.

30. The method of claim 28 wherein said at least one pre-selected region isolates at least two other regions within said nanotube fabric layer.

31. The method of claim 1 wherein said step of forming comprises depositing said plurality of nanotube elements on said substrate via one of a spin coating process, a spray coating process, a dip coating process, a silk screen printing process, or a gravure printing process.

32. The method of claim 1 wherein said plurality of nanotube elements are carbon nanotubes.

33. The method of claim 1 wherein said plurality of nanotube elements are single walled nanotubes.

34. The method of claim 1 wherein said plurality of nanotube elements are multi walled nanotubes.

53. The melhod of claim 1 wherein said step of functionalizing increases the density of switching sites within at least a portion of said nanotube fabric layer.

35. A method for forming a nanotube fabric layer, comprising:

functionalizing a plurality of nanotube elements;

disposing said functionalized plurality of nanotube elements on a substrate to form a nanotube fabric layer having an electrical resistance, wherein said electrical resistance of said nanotube fabric layer is capable of being switched among a plurality of non-volatile resistive states responsive to an applied electrical stimulus, said plurality of non-volatile resistive states falling within a conductivity range characterized by a lower limit and an upper limit; and

wherein said functionalizing limits at least one of said lower limit and said upper limit of said conductivity range of the nanotube fabric.

36. The method of claim 35 wherein said functionalizing decreases said upper limit of said conductivity range.

37. The method of claim 35 wherein said functionalizing increases said lower limit of said conductivity range.

38. The method of claim 35 wherein said functionalizing increases said upper limit of said conductivity range.

39. The method of claim 35 wherein said functionalizing decreases said lower limit of said conductivity range.

40. The method of claim 35 wherein said step of functionalizing increases the uniformity of said conductivity range.

41. The method of claim 35 wherein said step of functionalizing introduces at least one irreversible defect within said nanotube fabric layer.

42. The method of claim 35 wherein said step of functionalizing introduces at least one switching site within said nanotube fabric layer.

43. The method of claim 35 wherein said step of functionalizing eliminates at least one switching site within said nanotube fabric layer.

44. The method of claim 35 wherein said step of functionalizing comprises exposing said plurality of nanotube elements to a gas.

45. The method of claim 44 wherein said gas is one selected from the group consisting of nitrogen and argon.

46. The method of claim 35 wherein said step of functionalizing comprises combining a plurality of nanoscopic particles with said plurality of nanotube elements.

47. The method of claim 46 wherein said nanotube fabric layer comprises a mixture of said plurality of nanotube elements and said plurality of nanoscopic particles.

48. The method of claim 46 wherein said plurality of nanoscopic particles is one selected from the group consisting of silicon dioxide, silica, and silicon nitride.

49. The method of claim 35 wherein said step of disposing comprises depositing said plurality of nanotube elements on said substrate via one of a spin coating process, a spray coating process, a dip coating process, a silk screen printing process, or a gravure printing process.

50. The method of claim 35 wherein said plurality of nanotube elements are carbon nanotubes.

51. The method of claim 35 wherein said plurality of nanotube elements are single walled nanotubes.

52. The method of claim 35 wherein said plurality of nanotube elements are multi walled nanotubes.

54. The method of claim 35 wherein said step of functionalizing increases the density of switching sites within at least a portion of said nanotube fabric layer.