Large-area nanoenabled macroelectronic substrates and uses therefor
A method and apparatus for an electronic substrate having a plurality of semiconductor devices is described. A thin film of nanowires is formed on a substrate. The thin film of nanowires is formed to have a sufficient density of nanowires to achieve an operational current level. A plurality of semiconductor regions are defined in the thin film of nanowires. Contacts are formed at the semiconductor device regions to thereby provide electrical connectivity to the plurality of semiconductor devices. Furthermore, various materials for fabricating nanowires, thin films including p-doped nanowires and n-doped nanowires, nanowire heterostructures, light emitting nanowire heterostructures, flow masks for positioning nanowires on substrates, nanowire spraying techniques for depositing nanowires, techniques for reducing or eliminating phonon scattering of electrons in nanowires, and techniques for reducing surface states in nanowires are described.
1. An article, comprising a population of nanowires disposed over a surface of a substrate, wherein:
the population of nanowires is substantially oriented in a first direction; and
the surface of the substrate has an area of greater than 10 cm 2 .
2. The article of claim 1 , wherein the surface of the substrate has an area of greater than 1 m 2 .
3. The article of claim 1 , wherein the article further comprises at least first and second electrical contacts disposed on the surface of the substrate, and wherein at least 2 nanowires span and are electrically connected to the first and second electrical contacts.
4. The article of claim 3 , wherein at least 10 nanowires span and are electrically connected to the first and second electrical contacts.
5. The article of claim 1 , wherein greater than 60% of nanowires in the population of nanowires have a longitudinal axis that is oriented within 30° of the first direction.
6. The article of claim 1 , wherein greater than 75% of nanowires in the population of nanowires have a longitudinal axis that is oriented within 30° of the first direction.
7. The article of claim 1 , wherein greater than 80% of nanowires in the population of nanowires have a longitudinal axis that is oriented within 30° of the first direction.
8. The article of claim 1 , wherein greater than 90% of nanowires in the population of nanowires have a longitudinal axis that is oriented within 30° of the first direction.
9. The article of claim 1 , wherein greater than 50% of nanowires in the population of nanowires have a longitudinal axis that is oriented within 10° of the first direction.
10. The article of claim 1 , wherein the population of nanowires is disposed in a composite material.
11. The article of claim 10 , wherein the composite material comprises a polymer.
12. The article of claim 1 , wherein the substrate comprises a flexible substrate.
13. The article of claim 12 , wherein the substrate comprises a polymer.
14. The article of claim 1 , wherein the population of nanowires comprises nanowires selected from the group comprising Group II-VI semiconductors, Group III-V semiconductors and Group IV semiconductors.
15. The article of claim 1 , wherein the population of nanowires comprises a plurality of carbon nanotubes.
16. The article of claim 1 , wherein the population of nanowires comprises nanowires having a core of a first material at least partially surrounded by a shell of a compositionally different material.
17. The article of claim 16 , wherein said core material comprises silicon and said shell material comprises silicon oxide.
18. The article of claim 16 , wherein each of said core and said shell comprises a semiconductor material.
19. The article of claim 16 , wherein at least one of said core and said shell comprises a doped semiconductor material.
20. The article of claim 1 , wherein said population of nanowires comprise nanowires having a diameter of less than approximately 500 nm.
21. The article of claim 1 , wherein the article further comprises at least two pairs of electrical contacts disposed on the surface of the substrate, and wherein at least 2 nanowires span and are electrically connected to each pair of the electrical contacts.
22. The article of claim 1 , wherein individual members of the population of nanowires are positioned at discrete, separate areas of the substrate surface.
23. A method comprising:
forming a plurality of elongated nanostructures on a first substrate; and
transferring the plurality of nanostructures from the first substrate to a first surface of a second substrate, the first surface of the second substrate having a surface area greater than about 10 cm 2 ;
wherein the plurality of nanostructures are aligned on the first surface of the second substrate such that their long axes are substantially parallel to each other.
24. The method of claim 23 , wherein transferring the plurality of nanostructures comprises depositing the nanostructures in a thin film from solution onto the first surface of the second substrate.
25. The method of claim 24 , wherein the nanostructures are deposited onto the second substrate from solution using an electric field.
26. The method of claim 23 , wherein the plurality of nanostructures comprises nanowires having a core of a first material at least partially surrounded by one or more shells of a compositionally different material.
27. The method of claim 26 , wherein said core material comprises silicon and at least one of said one or more shells comprises silicon oxide.
28. The method of claim 26 , wherein each of said core and said one or more shells comprises a semiconductor material.
29. The method of claim 23 , wherein the population of nanostructures comprises nanoribbons.
30. The method of claim 23 , wherein the first surface of the second substrate has a surface area of greater than about 1 m 2 .
31. The method of claim 23 , wherein the second substrate comprises a polymer.
32. The method of claim 23 , wherein the plurality of nanostructures have an aspect ratio greater than 10.
33. The method of claim 23 , further comprising forming at least two pairs of electrical contacts on the first surface of the second substrate, wherein at least 2 nanostructures span and are electrically connected to each pair of the electrical contacts.
34. The method of claim 23 , wherein said transferring the plurality of nanostructures from the first substrate to the first surface of the second substrate comprises using micro-contact printing.