Large-area, free-standing metal oxide films and transistors made therefrom
The present invention provides continuous, free-standing metal oxide films and methods for making said films. The methods are able to produce large-area, flexible, thin films having one or more continuous, single-crystalline metal oxide domains. The methods include the steps of forming a surfactant monolayer at the surface of an aqueous solution, wherein the headgroups of the surfactant molecules provide a metal oxide film growth template. When metal ions in the aqueous solution are exposed to the metal oxide film growth template in the presence of hydroxide ions under suitable conditions, a continuous, free-standing metal oxide film can be grown from the film growth template downward into the aqueous solution.
1. A continuous, free-standing metal oxide film having as thickness of no greater than 10 μm and comprising at least one continuous, single-crystalline metal oxide domain having an area of at least 0.1 μm 2 .
2. The metal oxide film of claim 1 , wherein the at least one continuous, single-crystalline metal oxide domain has an area of at least 1 μm 2 .
3. The metal oxide film of claim 1 , wherein the at least one continuous, single-crystalline metal oxide domain has an area of at least 100 μm 2 .
4. The metal oxide film of claim 1 having a surface area of at least 1 cm 2 .
5. The metal oxide film of claim 1 , wherein the metal oxide is zinc oxide.
6. The metal oxide film of claim 5 having a thickness no greater than about 100 μm.
7. The metal oxide film of claim 5 , wherein the zinc oxide comprises the wurtzite phase of zinc oxide.
8. The metal oxide film of claim 5 , wherein the zinc oxide comprises a Zn 0.75 O x structure.
9. The metal oxide film of claim 1 , further comprising a surfactant associated with the surface of the metal oxide.
10. The metal oxide film of claim 1 , wherein the metal oxide is at least one of a magnesium oxide, a copper oxide, a titanium oxide, a tin oxide or a barium titanium oxide.
11. A continuous, free-standing zinc oxide film, wherein the zinc oxide has Zn 0.75 O x structure.
12. The zinc oxide film of claim 11 , comprising at least one continuous, single-crystalline Zn 0.75 O x domain having an area of at least 0.1 μm 2 .
13. The zinc oxide film of claim 11 , comprising at least one continuous, single-crystalline Zn 0.75 O x domain having an area of at least 1 μm 2 .
14. The zinc oxide film of claim 11 having a thickness of no greater than about 1000 nm.
15. A transistor incorporating the metal oxide film of claim 1 as an active Layer.
16. The metal oxide film of claim 5 having a thickness no greater than about 20 nm.
17. The metal oxide film of claim 1 , wherein the metal oxide film is adhered to an adhesive substrate comprising an adhesive layer on a flexible polymeric layer, wherein the adhesive substrate does not provide the metal film with its self-supporting structural integrity.
18. The metal oxide film of claim 7 , wherein the single-crystalline metal oxide domain is characterized by a hexagonal lateral perimeter.
19. The metal oxide film of claim 8 , wherein the single-crystalline metal oxide domain is characterized by a rectangular lateral perimeter.
20. The metal oxide film of claim 1 , wherein the single-crystalline metal oxide domain has a thickness of no greater than 1 μm, a length dimension of greater than 10 μm and a width dimension of greater than 10 μm.
21. The metal oxide film of claim 20 , wherein the single-crystalline metal oxide domain has a thickness of no greater than 100 nm and a length dimension or width dimension of at least 50 μm.
22. The metal oxide film of claim 20 , wherein the single-crystalline metal oxide domain has an area of at least 1000 μm 2 .