Methods of fabricating nanostructures and nanowires and devices fabricated therefrom
One-dimensional nanostructures having uniform diameters of less than approximately 200 nm. These inventive nanostructures, which we refer to as “nanowires”, include single-crystalline homostructures as well as heterostructures of at least two single-crystalline materials having different chemical compositions. Because single-crystalline materials are used to form the heterostructure, the resultant heterostructure will be single-crystalline as well. The nanowire heterostructures are generally based on a semiconducting wire wherein the doping and composition are controlled in either the longitudinal or radial directions, or in both directions, to yield a wire that comprises different materials. Examples of resulting nanowire heterostructures include a longitudinal heterostructure nanowire (LOHN) and a coaxial heterostructure nanowire (COHN).
1. A population of nanowires, comprising:
a plurality of nanowires, each comprising:
a core of a first semiconductor material at least partially surrounded by a sheath of a compositionally different material;
wherein at least one of said core and said sheath has a uniform diameter;
wherein said sheath material is synthesized; and
wherein the population of nanowires has a uniform interwire diameter of less than or equal to approximately 50% RMS across the population of nanowires.
2. A population of nanowires as recited in claim 1 , wherein said sheath comprises a non-amorphous material.
3. A population of nanowires as recited in claim 2 , wherein at least one of said core and said sheath comprises a crystalline material.
4. A population of nanowires as recited in claim 3 , wherein at least one of said core and said sheath comprises a monocrystalline material.
5. A population of nanowires as recited in claim 1 , wherein said at least one said core and said sheath has a diameter ranging from about 5 nm to about 50 nm.
6. A population of nanowires as recited in claim 1 , further comprising an electrode coupled to at least one of said core and said sheath.
7. A population of nanowires as recited in claim 1 , wherein said sheath comprises a crystalline material.
8. A population of nanowires as recited in claim 7 , wherein said crystalline material is monocrystalline.
9. A population of nanowires as recited as in claim 1 , comprising two or more sheath layers surrounding said core.
10. A population of nanowires as recited in claim 1 , wherein said core comprises at least first and second segments of compositionally different materials.
11. A population of nanowires as recited in claim 1 , wherein said sheath comprises a conformal carbon coating.
12. A population of nanowires as recited in claim 1 , wherein the sheath is selected from the group comprising: a metallic element, an oxide, a nitride, a selenide and a polymer.
13. A population of nanowires as recited in claim 1 , wherein the distribution of diameters within the population of nanowires is less than or equal to approximately 20% rms.
14. A population of nanowires as recited in claim 13 , wherein the distribution of diameters within the population of nanowires is less than or equal to approximately 10% rms.
15. A population of nanowires as recited in claim 1 , wherein the core comprises an inorganic material.
16. A population of nanowires as recited in claim 1 , wherein the core comprises silicon.
17. A population of nanowires as recited in claim 1 , wherein both the core and the sheath have a uniform diameter.
18. A population of nanowires, comprising:
a plurality of nanowires, each comprising:
a core of a first inorganic material at least partially surrounded by a sheath of a compositionally different material;
wherein at least one of said core and said sheath has a uniform diameter;
wherein said sheath material is synthesized; and
wherein the population of nanowires has a uniform interwire diameter of less than or equal to approximately 50% RMS across the population of nanowires.
19. A population of nanowires as recited in claim 18 , wherein the core comprises a semiconductor material.
20. A population of nanowires as recited in claim 19 , wherein the core comprises silicon.
21. A population of nanowires as recited in claim 18 , wherein both the core and the sheath have a uniform diameter.