Nanotube Device and Method of Fabrication

• US 20080317631A1
• Filed: 06/20/2007
• Published: 12/25/2008
• Est. Priority Date: 06/20/2007
• Status: Active Grant

• Current Assignee: New Jersey Institute of Technology
• Original Assignee: New Jersey Institute of Technology
• Inventors: Liu, Sheng, Goyal, Amit, Farrow, Reginald Conway, Iqbal, Zafar
• Granted Patent: US 7,964,143 B2
• Time in Patent Office: Days
• US Class Current: 422/68.1
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C25D 13/04 with organic material
• CPC Class Codes: C25D 13/20 Pretreatment
• CPC Class Codes: G01N 27/4146 involving nanosized elements, e.g. nanotubes, nanowires
• CPC Class Codes: Y10S 977/72 On an electrically conducting, semi-conducting, or semi-insulating substrate
• CPC Class Codes: Y10S 977/957 Of chemical property or presence
• CPC Class Codes: Y10S 977/958 Of biomolecule property

Abstract

A nanotube device and a method of depositing nanotubes for device fabrication are disclosed. The method relates to electrophoretic deposition of nanotubes, and allows a control of the number of deposited nanotubes and positioning within a defined region.

Claims

1. A method of depositing nanotubes, comprising:

(a) defining a region on a structure by an aperture;

(b) configuring the aperture to control a number of nanotubes to be deposited by electrophoresis in the region; and

(c) depositing the number of nanotubes in the region by electrophoresis.

2. The method of claim 1, wherein step (b) further comprises:

configuring the aperture to control at least one of a pattern and spacing of nanotubes to be deposited in the region.

3. The method of claim 1, wherein step (b) further comprises:

providing the aperture with a combination of length, width and depth to control the number of nanotubes to be deposited.

4. The method of claim 1, wherein step (b) further comprises:

providing the aperture with a lateral dimension to allow only one nanotube to be deposited in the region by electrophoresis.

5. The method of claim 4, wherein the lateral dimension of the aperture is less than about 100 nm.

6. The method of claim 1, wherein the aperture is configured as a slot having a width of less than about 100 nm, and a length sufficiently large to allow deposition of at least two nanotubes along a direction of the length.

7. The method of claim 1, wherein step (b) further comprises:

(b1) performing finite element analysis as a function of at least one parameter of the aperture to obtain an electric field distribution in proximity of the aperture; and

(b2) selecting a configuration of the aperture suitable for depositing the number of nanotubes in the region.

8. The method of claim 7, wherein at least one parameter for the nanotubes to be deposited is included in the finite element analysis.

9. The method of claim 1, wherein the nanotube is a carbon nanotube.

10. The method of claim 1, wherein:

step (a) further comprises;

(a1) providing the structure with an insulating layer over a metal layer; and

(a2) forming the aperture through the insulating layer to define the region at the metal layer.

11. The method of claim 10, wherein step (c) further comprises:

(c1) exposing the structure to an electrolytic fluid containing nanotubes;

(c2) applying a bias voltage to the metal layer; and

(c3) depositing the number of nanotubes in a vertical orientation to contact the metal layer inside the aperture.

12. The method of claim 11, wherein the number of nanotubes is one.

13. The method of claim 12, wherein the nanotube is deposited to be substantially centered inside the aperture.

14. The method of claim 11, wherein step (c) further comprises:

(c4) providing a metal electrode in the electrolytic fluid; and

(c5) providing a positive bias to the metal electrode relative to the metal layer.

15. The method of claim 14, further comprising:

controlling orientations of the nanotubes inside the aperture by adjusting an orientation of the metal electrode relative to the metal layer.

16. The method of claim 1, wherein the aperture has a height to width ratio of at least about 0.18.

17. A nanotube-based sensor, comprising:

an insulating layer over a metal contact formed on a substrate;

an aperture formed in the insulating layer, the aperture extending to the metal contact and defining a region at the metal contact;

a nanotube disposed inside the aperture and having a first end contacting the region at substantially a center of the region, and a second end coupled to a molecule having a functional group for interacting with a sample.

18. The device of claim 17, being one of a chemical sensor or a biosensor.

19. The device of claim 17, wherein the nanotube is a carbon nanotube.

20. The device of claim 17, wherein the sensor further comprises an insulating layer surrounding the nanotube.

21. A method of forming a carbon nanotube-based device, comprising:

providing a substrate with an insulating layer formed on a conductive layer;

forming an aperture through the insulating layer to expose a region of the conductive layer;

immersing the substrate in an electrolytic fluid containing carbon nanotubes;

providing a metal electrode in the electrolytic fluid;

applying a bias voltage across the conductive layer and the metal electrode; and

depositing at least one carbon nanotube in a substantially perpendicular orientation with respect to the region, wherein one end of the carbon nanotube contacts the region proximate a center of the region.

22. The method of claim 21, further comprising:

providing the substrate with the at least one deposited carbon nanotube to a plasma process system for further processing;

re-aligning the at least one deposited carbon nanotube to a desired orientation by applying an electric field between the conductive layer and an electrode in the plasma process system.