Radio frequency device and method using a carbon nanotube array

• US 7,157,990 B1
• Filed: 05/21/2004
• Issued: 01/02/2007
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Adam, John Douglas, Young, Robert Miles
• Primary Examiner(s): Summons; Barbara
• Application Number:
  US10/850,152
• Time in Patent Office: 956 Days
• Field of Search: 333/186
• US Class Current: 333/186
• CPC Class Codes: H03H 2009/02488 Vibration modes
• CPC Class Codes: H03H 9/02259 Driving or detection means
• CPC Class Codes: H03H 9/2405 of microelectro-mechanical resonators
• CPC Class Codes: H03H 9/505 for microelectro-mechanical filters
• CPC Class Codes: Y10S 977/723 On an electrically insulating substrate
• CPC Class Codes: Y10S 977/724 Devices having flexible or movable element
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/932 for electronic or optoelectronic application

Abstract

A radio frequency (RF) filter includes a substrate, first and second dielectric layers formed on first and second portions of the substrate, a ground plane formed on a third portion of said substrate, a carbon nanotube array, and first and second electrodes. The third portion of the substrate includes, at least in part, the area between the first and second portions thereof. The carbon nanotube array is formed on a portion of said ground plane between the first and second dielectric layers. The first and second electrodes are formed on the first and second dielectric layers, such that an RF signal may be input to and output from the carbon nanotube array via the first and second signal guides. A third electrode is disposed over the carbon nanotube array and is used to voltage bias the array.

Claims

1. A radio frequency (RF) filter, comprising:

a substrate;

a dielectric layer formed on first and second portions of said substrate;

a ground plane formed on a third portion of said substrate, said third portion being at least, in part, between said first and second portions;

a carbon nanotube array being formed on a portion of said ground plane between said first and second dielectric layers; and

first and second signal guides formed on the first and second dielectric layers, such that an RF signal may be input to and output from said carbon nanotube array via said first and second signal guides.

2. The filter as recited in claim 1, wherein first and second portions of said dielectric layer are adjacent to first and second sides of said carbon nanotube array, respectively.

3. The filter as recited in claim 2, wherein said first and second signal guides are adjacent to said first and second sides of said carbon nanotube array, respectively.

4. The filter as recited in claim 1, wherein said first and second signal guides comprise a highly conductive material.

5. The filter as recited in claim 1, wherein first and second signal guides have substantially a same perimeter shape as said first and second dielectric layers.

6. The filter as recited in claim 1, wherein said first and second dielectric layers have a trapezoidal shape, each having a narrow side adjacent to a side of said carbon nanotube array.

7. The filter as recited in claim 6, wherein said first and second dielectric layers have a same thickness as a height of said carbon nanotube array.

8. The filter as recited in claim 7, wherein said first and second signal guides and said ground plane form a co-planar wave guide.

9. The filter as recited in claim 1, wherein said first and second signal guides and said ground plane form a co-planar wave guide.

10. The filter as recited in claim 1, wherein said substrate comprises silicon and said first and second dielectric layers comprise aluminum oxide.

11. The filter as recited in claim 1, wherein said first and second dielectric layers have a same thickness as a height of said carbon nanotube array.

12. The filter as recited in claim 11, wherein said first and second signal guides and said ground plane form a co-planar wave guide.

13. The filter as recited in claim 12, wherein said first and second dielectric layers have a trapezoidal shape, each having a narrow side adjacent to a side of said carbon nanotube array.

14. The filter as recited in claim 13, wherein first and second signal guides have substantially a same perimeter shape as said first and second dielectric layers.

15. The filter as recited in claim 14, wherein said first and second signal guides have first and second sides that are adjacent to said first and second sides of said carbon nanotube array.

16. The filter as recited in claim 15, wherein said first and second sides of said first and second signal guides have a same width as the width of said carbon nanotube array.

17. The filter as recited in claim 16, wherein said first and second signal guides comprise a highly conductive material.

18. The filter as recited in claim 17, wherein said first and second signal guides comprise gold.

19. The filter as recited in claim 1, further comprising first and second electrodes being formed over said carbon nanotube array, said first and second electrodes being separated by carbon nanotubes and are coupled with said first and second signal guides respectively.

20. The filter as recited in claim 19, wherein said first and second electrodes have a comb-tooth shape and teeth of said first electrode are formed between teeth of said second electrode.

21. The filter as recited in claim 20, wherein said first and second signal guides comprise strip-line type feeds.

22. The filter as recited in claim 1, wherein said first and second signal guides comprise slot-line type signal guides, having at least a single slot formed over said carbon nanotube array.

23. The filter as recited in claim 22, where said first and second signal guides have a plurality of slots formed over said carbon nanotube array.

24. The filter as recited in claim 1, further comprising an electrode disposed above said carbon nanotube array, separated from said array by an air gap, said electrode being DC biased.

25. The filter as recited in claim 24, further comprising a means for providing a magnetic field to said carbon nanotube array.

26. The filter as recited in claim 24, wherein said magnetic field is applied in a direction parallel to a length of each nanotube of said array.

27. A resonator, comprising:

a substrate;

a ground plane formed on a portion of said substrate;

a carbon nanotube array being formed on said ground plane;

first and second electrodes formed on said substrate as input and output to said carbon nanotube array, each of said first and second electrodes being separated from said ground plane by a gap; and

a magnet which generates a magnetic field parallel to the carbon nanotubes of said array.

28. The resonator as recited in claim 27, wherein said first and second electrodes are formed on opposite sides of said carbon nanotube array.

29. The resonator as recited in claim 27, wherein said substrate comprises a dielectric material.

30. The resonator as recited in claim 29, wherein said dielectric material comprises sapphire.

31. The resonator as recited in claim 27, wherein said first and second electrodes comprise a conductive material.

32. The resonator as recited in claim 31, wherein said first and second electrodes comprise gold.

33. The resonator as recited in claim 27, further comprising an electrode disposed above said carbon nanotube array, separated from said array by an air gap, said electrode being DC biased.

34. A radio frequency (RF) filter, comprising:

a substrate;

a dielectric layer formed on the substrate;

a ground plane formed on said substrate in a well in said dielectric layer;

a carbon nanotube array formed on said ground plane;

first and second electrodes formed on first and second portions of said dielectric layer and extending at least partially over said carbon nanotube array, such that an RF signal may be input to and output from said carbon nanotube array via at least one of said first and second electrodes; and

a third electrode disposed over said carbon nanotube array.

35. The RF filter as recited in claim 34, wherein said third electrode is provided with a DC voltage.

36. The RF filter as recited in claim 34, further comprising a magnet providing a magnetic field in a direction parallel to the carbon nanotubes of said carbon nanotube array.

37. The RF filter as recited in claim 34, wherein said first and second electrodes act as first and second ports.

38. The RF filter as recited in claim 34, further including forth fourth and fifth electrodes, and wherein said first and third electrodes are on opposite sides of said array from said second and fourth electrodes, and said first electrode acts as a port, said second and third electrodes are connected to ground and said fourth electrode acts as a port.

39. The RF filter as recited in claim 34, wherein said portion of said first electrode which extends overtop of said array includes a first set of teeth, said portion of said second electrode which extends overtop of said array includes a second set of teeth, said first set of teeth extending at least partially into gaps formed between the teeth of said second set of teeth without said first and second electrodes contacting.

40. The RF filter as recited in claim 39, further comprising a magnet providing a magnetic field in a direction parallel to the carbon nanotubes of said carbon nanotube array.

41. The RF filter as recited in claim 34, wherein said first and second electrodes comprise strip-line type electrodes.

42. The RF filter as recited in claim 41, wherein said portion of said first electrode which extends overtop of said array includes a first set of teeth, said portion of said second electrode which extends overtop of said array includes a second set of teeth.

43. The RF filter as recited in claim 34, wherein said substrate comprises a dielectric material.

44. The RF filter as recited in claim 34, wherein said dielectric layer has a thickness equal to the height of the carbon nanotubes of said carbon nanotube array.

45. The RF filter as recited in claim 34, wherein said first electrode acts as a port and said second electrode is connected to ground.

46. The RF filter as recited in claim 45, wherein said portion of said first electrode which extends overtop of said array includes a first set of teeth, said portion of said second electrode which extends overtop of said array includes a second set of teeth, said first set of teeth extending at least partially into gaps formed between the teeth of said second set of teeth without said first and second electrodes contacting.

47. The RF filter as recited in claim 46, further comprising a magnet providing a magnetic field in a direction parallel to the carbon nanotubes of said carbon nanotube array.

48. A method for filtering a radio frequency (RF) signal, comprising steps of:

providing a carbon nanotube array;

providing an input and output to said carbon nanotube array;

voltage biasing said carbon nanotube array;

providing a magnetic field parallel to carbon nanotubes of said carbon nanotube array; and

providing said RF signal to said input of said carbon nanotube array.

49. The method as recited in claim 48, wherein said input and output to said carbon nanotube array comprise quasi-coplanar waveguides.

50. The method as recited in claim 48, wherein said input and output to said carbon nanotube array comprise strip-lines.

51. The method as recited in claim 50, wherein said strip-lines include a plurality of teeth extending, at least partially over said carbon nanotube array.

52. The method as recited in claim 51, further comprising a step of selecting a number of teeth of said plurality of teeth based on a desired frequency response for said filter.

53. The method as recited in claim 52, further comprising a step of tuning said filter by adjusting a strength of at least one of said voltage bias and said magnetic field.

54. The method as recited in claim 48, wherein said input and output to said carbon nanotube array comprise interdigital electrodes.

55. The method as recited in claim 54, wherein said interdigital electrodes include a plurality of teeth extending, at least partially over said carbon nanotube array.

56. The method as recited in claim 55, further comprising a step of selecting a number of teeth of said plurality of teeth based on a desired frequency response for said filter.

57. The method as recited in claim 56, further comprising a step of tuning said filter by adjusting a strength of at least one of said voltage bias and said magnetic field.

58. A method for fabricating a radio frequency (RF) filter, comprising steps of:

forming a dielectric layer onto a first substrate;

removing a portion of said dielectric layer;

forming a first conductor layer onto the portion exposed by said removing step;

forming a carbon nanotube array onto said first conductor;

forming second and third conductor layers onto said dielectric layer and a signal input and output to said carbon nanotube array;

bonding a second substrate on top of said second and third conductor layers; and

forming a fourth conductor layer on top of said second substrate.

59. The method as recited in claim 58, further comprising a step of forming first and second interdigital electrodes onto said second substrate before said bonding step, and wherein said bonding step is such that said first and second interdigital electrodes are connected with said second and third conductors respectively.

60. The method as recited in claim 59, wherein said carbon nanotubes are formed such that tips of each nanotubes do not extend above said second and third conductor layers, and said first and second interdigital electrodes each include a plurality of teeth extending, at least partially over said carbon nanotube array, after bonding.

61. The method as recited in claim 60, further comprising a step of selecting a number of teeth of each said plurality of teeth based on a desired frequency response for said RF filter, said teeth formed such that said first plurality of teeth are formed in gaps between said second plurality of teeth, without said first plurality of teeth contacting said second plurality of teeth.

62. The method as recited in claim 60, wherein said first conductor layer is connected to ground and said fourth conductor layer is set to a DC voltage potential.

63. The method as recited in claim 58, wherein said first conductor layer is connected to ground and said fourth conductor layer is set to a DC voltage potential.

64. A structure that is capable of being used in a filter or a resonator, comprising:

a dielectric layer formed on a substrate;

a ground plane formed on said substrate in a well in said dielectric layer;

a carbon nanotube array formed on said ground plane;

first and second electrodes formed on first and second portions of said dielectric layer and extending at least partially over said carbon nanotube array, such that an RF signal may be input to and output from said carbon nanotube array via at least one of said first and second electrodes; and

a third electrode disposed over said carbon nanotube array.