Nanostructure production methods and apparatus
The present invention relates to a method of forming nanostructures or nanomaterials. The method comprises providing a thermal control barrier on a substrate and forming the nanostructures or nanomaterials. The method may, for example, be used to form carbon nanotubes by plasma enhanced chemical vapor deposition using a carbon containing gas plasma: The temperature of the substrate may be maintained at less than 350° C. while the carbon nanotubes are formed.
1. A method of forming nanostructures or nanomaterials including the steps of:
providing a thermal control barrier as a substantially continuous layer on a substrate;
providing a gas plasma;
providing heating at the thermal control barrier from above the layer by a heating source distinct from the gas plasma, wherein the heating source is an optical heating source; and
forming the nanostructures or nanomaterials on the substrate atop the layer by plasma enhanced chemical vapour deposition using the gas plasma during said heating.
2. A method according to claim 1 , wherein the method is for producing nanostructures which are carbon nanotubes or carbon nanowires and wherein the step of forming the nanostructures uses a carbon containing gas plasma.
3. A method according to claim 1 , wherein the temperature of the substrate is less than 350° C. while the nanostructures or nanomaterials are formed.
4. A method according to claim 1 , wherein a catalyst is provided on the thermal control barrier in a substantially continuous layer before the nanostructures or nanomaterials are formed or simultaneously with the formation of the nanostructures or nanomaterials.
5. A method according to claim 1 , wherein the thermal control barrier is deposited on the substrate.
6. A method according to claim 1 , wherein the thermal control barrier has a thickness of greater than or equal to 3 nm.
7. A method according to claim 1 , wherein the thermal control barrier is a layer of metal, semiconductor or dielectric material.
8. A method according to claim 1 , comprising the step of providing a catalyst on the thermal control barrier.
9. A method according to claim 8 , wherein the catalyst is a metal, or mixture of metals.
10. A method according to claim 1 , further comprising the step of uniformly cooling the substrate.
11. A method according to claim 10 , wherein a second surface of the substrate is cooled while said nanostructures or nanomaterials are formed on a first surface of said substrate.
12. A method according to claim 11 , comprising supplying a coolant fluid to a cooling well to cool the substrate.
13. A method according to claim 11 , comprising the step of introducing a gas at the interface between said second surface and a surface on which the substrate is supported.
14. A method according to claim 13 , wherein said gas is hydrogen.
15. A method according to claim 10 , comprising supplying a coolant fluid to a cooling well to cool the substrate.
16. A method according to claim 15 , comprising the step of introducing a gas at the interface between said second surface and a surface on which the substrate is supported.
17. A method according to claim 16 , wherein said gas is hydrogen.
18. A method according to claim 1 , wherein said thermal control barrier is optically reflective.
19. A method according to claim 1 , wherein the thermal control barrier is a thermal insulator.
20. A method according to claim 1 , comprising providing at least one device on the substrate.
21. A method according to claim 20 , wherein the thermal control barrier is provided over said at least one device.
22. A method according to claim 21 , wherein said at least one device is at least substantially covered by said thermal control barrier.
23. A method according to claim 20 , wherein the device is an electronic component.
24. A method according to claim 23 , wherein the electronic component is a transistor.
25. A method according to claim 1 , wherein the steps are repeated to form a multilayered structure.
26. A method according to claim 1 , wherein said substrate is a plastics material.
27. A method according to claim 1 , further comprising the step of controlling an electric field across the substrate to align the nanostructures or nanomaterials.