Contact metallization of carbon nanotubes
In one embodiment, SWNTs are synthesized from an embedded catalyst in a modified porous anodic alumina (PAA) template. Pd is electrodeposited into the template to form nanowires that grow from an underlying conductive layer beneath the PAA and extend to the initiation sites of the SWNTs within each pore. Individual vertical channels of SWNTs are created, each with a vertical Pd nanowire back contact. Further Pd deposition results in annular Pd nanoparticles that form on portions of SWNTs extending onto the PAA surface. Two-terminal electrical characteristics produce linear I-V relationships, indicating ohmic contact in the devices.
1. A method of metallizing an array of carbon nanotubes, comprising:
fabricating a template including a base conducting layer, a first layer of a material on top of the conductive layer, a second layer of catalytic material on top of the first layer, and a third layer of the material on top of the second layer;
forming a plurality of pores in the first, second, and third layers;
synthesizing at least one carbon nanotube from the catalytic layer in each of a plurality of pores;
placing the porous template in a solution containing metallic ions after said synthesizing; and
electrodepositing a quantity of metal in each of the plurality of pores sufficient to establish electrical contact from the nanotube to the conductive material.
2. The method of claim 1 wherein the template includes alumina, and which further comprises removing a quantity of alumina from the bottom of a pore prior to said electrodepositing.
3. The method of claim 2 wherein said removing is by exposure to a plasma with a reducing agent, by reverse anodic anodization, or by ion milling.
4. A method of metallizing an array of carbon nanotubes, comprising:
fabricating a template of first and second layers of a material separated by a catalytic layer, at least a portion of one outer surface of a layer of the material having an electrically conductive material deposited thereon;
forming a plurality of pores in the template;
removing a portion of the material in the bottom of a pore;
synthesizing at least one carbon nanotube from the catalytic layer in the pore;
placing the porous template in a solution containing metallic ions after said synthesizing; and
electrodepositing a quantity of the metal in the pore.
5. The method of claim 4 wherein the template has an external surface, and which further comprises removing a portion of the nanotube extending beyond the external surface.
6. The method of claim 4 wherein said fabricating includes a third layer of aluminum separated from the second layer of aluminum by a second catalytic layer.
7. The method of claim 6 which further comprises synthesizing a second carbon nanotube in the pore from the second catalytic layer.
8. The method of claim 1 wherein the template has an external surface, and which further comprises removing a portion of the nanotube extending beyond the external surface.
9. The method of claim 1 wherein said fabricating includes a fourth layer of the material separated from the third layer of the material by a fifth layer of catalytic material.
10. The method of claim 9 which further comprises synthesizing a second carbon nanotube in the pore from the fifth catalytic layer.
11. The method of claim 1 wherein the carbon nanotube is a single walled carbon nanotube.
12. The method of claim 4 wherein the carbon nanotube is a single walled carbon nanotube.
13. The method of claim 4 wherein said forming is by anodizing.
14. The method of claim 4 wherein the one carbon nanotube is the only carbon nanotube in the pore.
15. The method of 1 wherein the one carbon nanotube is the only carbon nanotube in the pore.