Photolithographically defined contacts to carbon nanostructures
Methods for the fabrication of nanostructures, including nanostructures comprised of carbon nanotubes, and the nanostructures, devices, and assemblies prepared by these methods, are described.
1. A method for fabricating a nanostructure comprising:
(a) providing a substrate having at least one nanodimensioned device superposed upon it;
(b) overlaying at least a portion of the nanodimensioned device with a layer of a passivating material to form a passivating layer which does not substantially interact with the nanodimensioned device by pi-pi overlap or covalent or ionic bonding; and
(c) coating at least a portion of the overlaid passivating layer with at least one photoresist;
wherein the nanodimensioned device comprises a conducting nanotube or nanowire, a semiconducting nanotube or nanowire, a metallic nanotube or nanowire, a mat of conducting, semiconducting, or metallic nanotubes or nanowires, or combinations thereof; and
wherein the passivating material is a photosensitive aliphatic organic polymer or copolymer or comprises an aliphatic organic polymer or copolymer precursor or a saturated wax or aliphatic surfactant, said passivating material being susceptible to imaging and photoprocessing.
2. The method of claim 1 , wherein the substrate is comprised of silicon, gallium arsenide, or indium phosphide, optionally coated with silicon dioxide.
3. The method of claim 1 , wherein the substrate is comprised of doped silicon coated with silicon dioxide.
4. The method of claim 3 , wherein the silicon dioxide layer has a thickness in a range of about 50 nanometers to about 500 nanometers.
5. The method of claim 1 wherein the nanodimensioned device comprises at least one carbon nanotube or nanowire, graphene, graphene oxide, reduced graphene oxide, or mixtures thereof.
6. The method of claim 1 wherein the nanodimensioned device comprises carbon nanotubes.
7. The method of claim 1 , wherein the nanodimensioned device contains a microelectromechanical device.
8. The method of claim 1 , wherein the nanodimensioned device is deposited upon the substrate by chemical vapor deposition.
9. The method of claim 1 wherein the passivating material is substantially free of pi-bond conjugated aromatic species.
10. The method of claim 1 wherein at least one passivating material layer is applied by spin coating.
11. The method of claim 1 wherein at least one passivating material comprises an aliphatic organic polymer or copolymer, or comprises an aliphatic organic polymer or copolymer precursor.
12. The method of claim 1 wherein at least one passivating material comprises a saturated wax or aliphatic surfactant.
13. The method of claim 11 , wherein at least one polymers or polymer precursor layers comprises a polyglutarimide or polyalkyl glutarimide.
14. The method of claim 11 , wherein at least one polymers or polymer precursor layers comprises a saturated acrylate, polyester, or polyolefin.
15. The method of claim 1 , wherein at least one passivating layer is at least about 10 nanometers thick.
16. The method of claim 1 , wherein at least one passivating layer has a thickness in a range of from about 10 nanometers to about 100 nanometers.
17. The method of claim 1 , wherein at least one passivating layer has a thickness in a range of from about 25 nanometers to about 75 nanometers.
18. The method of claim 1 , wherein at least one photoresist comprises phenolic, poly(vinyl cinnamate), or styrene polymers, co-polymers, or mixtures thereof.
19. The method of claim 1 , wherein at least one photoresist is deposited by spin coating, dip coating, painting, or screen printing.
20. The method of claim 1 , wherein at least one layer of photoresist has a thickness in a range of from about 20 nanometers to about 10,000 nanometers.
21. The method of claim 1 , wherein at least one layer of photoresist is about 0.1 microns thick.
22. The method of claim 1 , wherein at least one photoresist is a positive-tone photoresist.
23. The method of claim 1 further comprising the simultaneous imaging of a plurality of patterns on the substrate.
24. The method of claim 1 further comprising image-wise removing portions of the photoresist and the passivating layer to form at least one pattern in which at least some part of at least one nanodimensioned device is not covered by the photoresist and the passivating material layer.
25. The method of claim 24 further comprising applying electrically conducting or semiconducting material to at least some portions of the nanodimensioned device exposed by removal of the photoresist and passivating material portions, such that contact is made between the electrically conducting or semiconducting material and at least some part of at least one nanodimensioned device.
26. The method of claim 25 , wherein the electrically conducting material is at least one metal.
27. The method of claim 26 , wherein the at least one metal is chromium, copper, or gold.
28. The method of claim 26 , wherein multiple metals are deposited sequentially.
29. The method of claim 26 , wherein the at least one metal is deposited by sputtering or chemical vapor deposition.
30. The method of claim 25 wherein the method provides an electrical circuit.
31. The method of claim 25 further comprising annealing the nanostructure.
32. The method of claim 31 , wherein the annealing temperature is above the boiling points of any solvents used in the processing or solvents or monomers originally contained in the at least one passivating material or the at least one photoresist.
33. The method of claim 31 , wherein the annealing temperature is from about 100 to about 300 degrees Celsius.
34. The method of claim 25 further comprising adhering biological molecules to at least some portions of the nanodimensioned devices.
35. The method of claim 25 , further comprising applying a protective coating over the nanostructure.
36. A method for fabricating a nanostructure comprising:
(a) providing a substrate having at least one nanodimensioned device superposed upon it, wherein the nanodimensioned device comprises a conducting nanotube or nanowire, a semiconducting nanotube or nanowire, a metallic nanotube or nanowire, a mat of conducting, semiconducting, or metallic nanotubes or nanowires, or combinations thereof;
(b) overlaying at least a portion of the nanodimensioned device with a layer of a passivating material to form a passivating layer, the passivating layer being a photosensitive aliphatic organic polymer or copolymer, or comprises an aliphatic organic polymer or copolymer precursor or a saturated wax or aliphatic surfactant, said passivating material being susceptible to imaging and photoprocessing and, which does not substantially interact with the nanodimensioned device by pi-pi overlap or covalent or ionic bonding;
(c) coating at least a portion of the passivating layer with at least one photoresist;
(d) image-wise removing portions of the photoresist and the passivating material layer to form a pattern in which at least some part of at least one nanodimensioned device is not covered by the photoresist and the passivating material layer;
(e) applying electrically conducting or semiconducting material to at least some portions of the nanodimensioned device exposed by removal of the photoresist and the passivating material portions, such that contact is made between the electrically conducting or semiconducting material and at least some part of at least one nanodimensioned device;
(f) optionally repeating steps (b) through (e) at least once; and
(g) optionally annealing the nanostructure.
37. A nanostructure or array of nanostructures fabricated from the method of claim 1 .
38. A nanostructure comprising a substrate having at least one nanodimensioned device superposed upon it, wherein at least a portion of the nanodimensioned device is coated with at least one layer of a passivating material which does not substantially interact with the nanodimensioned device by pi-pi overlap or covalent or ionic bonding;
wherein the nanodimensioned device comprises a conducting nanotube or nanowire, a semiconducting nanotube or nanowire, a metallic nanotube or nanowire, a mat of conducting, semiconducting, or metallic nanotubes or nanowires, or combinations thereof; and
wherein the passivating layer comprises a photosensitive aliphatic organic polymer or copolymer, or comprises an aliphatic organic polymer or copolymer precursor or a saturated wax or aliphatic surfactant, said passivating material being susceptible to imaging and photoprocessing.
39. An assembly comprising the nanostructure of claim 37 .