GRAPHENE SHEET AND METHOD FOR PRODUCING THE SAME

• US 20120196074A1
• Filed: 08/31/2010
• Published: 08/02/2012
• Est. Priority Date: 08/31/2009
• Status: Active Grant

• Current Assignee: Kyushu University
• Original Assignee: Kyushu University
• Inventors: Ago, Hiroki, Ito, Yoshito, Tanaka, Izumi, Mizuno, Seigi, Tsuji, Masaharu
• Granted Patent: US 8,697,230 B2
• Time in Patent Office: Days
• US Class Current: 428/64.1
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 2204/02 Single layer graphene
• CPC Class Codes: C01B 2204/04 Specific amount of layers or specific thickness
• CPC Class Codes: C01B 2204/32 Size or surface area
• CPC Class Codes: C01B 32/188 by epitaxial growth
• CPC Class Codes: Y10T 428/21 Circular sheet or circular blank
• CPC Class Codes: Y10T 428/24777 Edge feature
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

To provide a graphene sheet that has a large area, is homogeneous, and has a small amount of domain boundaries, a novel method for producing a graphene sheet suitable for industrial applications, such as application to electronics, that is capable of producing a graphene sheet that has well aligned crystal orientation at a low cost, and a graphene sheet.

In the method for producing a graphene sheet of the present invention, a substrate containing a single crystal substrate having formed on the surface thereof an epitaxial metal film is used, and a graphene sheet is grown by making a carbon material into contact with the surface of the epitaxial metal film. In the graphene sheet of the present invention, the graphene sheet is constituted by a number of graphene domains, the domains each have an area of from 0.000001 μm² to 100,000 mm², and the orientations of 6-membered rings in the domains are averagely aligned in a single direction over the graphene sheet.

Claims

1. A graphene sheet comprising a large number of graphene domains, the domains each having an area of from 0.000001 μ

m² to 100,000 mm², orientations of 6-membered rings in the domains being averagely aligned in a single direction over the graphene sheet.

2. The graphene sheet according to claim 1, wherein an in-plane mis-orientation of 6-membered rings is such that 90% or more of the domains have orientations aligned within ±

5°

or less.

3. The graphene sheet according to claim 1, wherein an in-plane mis-orientation of 6-membered rings is such that 90% or more of the domains have orientations aligned within ±

10°

or less.

4. The graphene sheet according to claim 1, wherein the graphene sheet containing a large number of domains has an overall size of from 1 mm² to 50,000 mm².

5. The graphene sheet according to claim 1, wherein a proportion of graphene that has the same number of layers is 90% or more.

6. The graphene sheet according to claim 5, wherein a proportion of single layer graphene is 90% or more.

7. The graphene sheet according to claim 1, wherein a proportion of single layer graphene is 50% or more.

8. The graphene sheet according to claim 1, wherein a proportion of two-layer graphene is 50% or more.

9. The graphene sheet according to claim 1, wherein a proportion of three-layer graphene is 50% or more.

10. A composite of a graphene sheet comprising the graphene sheet according to claim 1 that is transferred to a substrate, and having a size of from 10 nm² to 1 m².

11. A composite of a graphene sheet comprising a metal film, and the graphene sheet according to claim 1 that is grown on a surface of the metal film.

12. A composite of a graphene sheet comprising a single crystal substrate, an epitaxial metal film that is formed on the single crystal substrate, and the graphene sheet according to claim 1 that is grown on a surface of the metal film.

13. The composite of a graphene sheet according to claim 11, wherein a LEED (low energy electron diffraction) image of the composite containing the graphene sheet has six equally spaced diffraction spots.

14. The composite of a graphene sheet according to claim 11, wherein a LEED image of the composite containing the graphene sheet has six equally spaced diffraction spots and a ring diffraction pattern having intensity that is locally distributed around the center of spots.

15. The composite of a graphene sheet according to claim 11, wherein a LEED image of the composite containing the graphene sheet has six equally spaced diffraction spots and a ring diffraction pattern that is locally distributed to twelve spots.

16. A graphene sheet obtained by growing in a pit formed on a surface of an epitaxial metal film.

17. A composite of a graphene sheet comprising a metal film, and the graphene sheet according to claim 16 that is grown in a pit formed on a surface of the metal film.

18. A composite of a graphene sheet comprising a single crystal substrate, an epitaxial metal film that is formed on the single crystal substrate, and the graphene sheet according to claim 16 that is grown in a pit formed on a surface of the metal film.

21. The graphene sheet according to claim 16, wherein the graphene sheet is transferred to a substrate.

19. A graphene sheet having a triangular, rectangular, hexagonal, octagonal or circular planar shape having an area of from 0.0001 to 1,000,000 μ

m², and having a thickness of from 1 to 20 layers.

20. A graphene sheet having a planar shape having an edge with a zigzag structure or an armchair structure having an area of from 0.0001 to 1,000,000 μ

m², and having a thickness of from 1 to 20 layers.

22. A method for producing a graphene sheet, comprising a step of growing a graphene sheet by making a carbon material into contact with a surface of an epitaxial metal film that is formed on a surface of a single crystal substrate.

23. The method for producing a graphene sheet according to claim 22, wherein the graphene sheet is grown on the entire surface of the epitaxial metal film that is made in contact with the carbon material.

24. The method for producing a graphene sheet according to claim 22, wherein the graphene sheet is grown on 80% or more of the surface of the epitaxial metal film that is made in contact with the carbon material.

25. The method for producing a graphene sheet according to claim 22, wherein the graphene sheet is grown on 50% or more of the surface of the epitaxial metal film that is made in contact with the carbon material.

26. The method for producing a graphene sheet according claim 22, wherein the graphene sheet grown has a proportion of graphene that has the same number of layers of 90% or more.

27. The method for producing a graphene sheet according to claim 22, wherein the graphene sheet grown has a proportion of graphene that has the same number of layers of 70% or more.

28. The method for producing a graphene sheet according to claim 22, wherein the graphene sheet grown has a proportion of graphene that has the same number of layers of 50% or more.

29. The method for producing a graphene sheet according to claim 26, wherein the graphene that has the same number of layers is any one selected from single layer graphene, two-layer graphene and three-layer graphene.

30. The method for producing a graphene sheet according to claim 22, wherein orientations of 6-membered rings in domains constituting the graphene sheet are averagely aligned in a single direction over the graphene sheet.

31. The method for producing a graphene sheet according to claim 30, wherein a LEED (low energy electron diffraction) image of the graphene sheet and a composite containing the metal film have six equally spaced diffraction spots.

32. The method for producing a graphene sheet according to claim 30, wherein a LEED image of the substrate having the graphene sheet formed thereon has six equally spaced diffraction spots and a ring diffraction pattern having intensity that is locally distributed around the center of spots.

33. The method for producing a graphene sheet according to claim 30, wherein a LEED image of the substrate having the graphene sheet formed thereon has a ring diffraction pattern that is locally distributed to twelve spots.

34. The method for producing a graphene sheet according to claim 22, wherein the graphene sheet has an average domain size of 0.0001 μ

m² or more.

35. The method for producing a graphene sheet according to claim 22, wherein the single crystal substrate is a single crystal substrate of α

-Al₂O₃, MgO or quartz (SiO₂).

36. The method for producing a graphene sheet according to claim 22, wherein the epitaxial metal film is a film of at least one member selected from Co, Ni, Fe, Cu, Pt, Pd, Ru, Au, Ir, Ti, Al, Ag, Mg, Mn, Cr and Sn.

37. The method for producing a graphene sheet according to claim 22, wherein the graphene sheet is grown on the epitaxial metal film by chemical vapor deposition (CVD) under a pressure of from the atmospheric pressure to a reduced pressure by feeding carbon-containing molecules in a gaseous state.

38. The method for producing a graphene sheet according to claim 37, wherein the substrate is subjected to hydrogen annealing at a temperature lower than a temperature upon synthesis of the graphene sheet, before synthesis of the graphene sheet.

39. The method for producing a graphene sheet according to claim 22, wherein an organic polymer film is formed on the surface of the epitaxial metal film, and then the organic polymer is thermally decomposed in vacuum, thereby growing the graphene sheet.

40. The method for producing a graphene sheet according to claim 22, wherein the graphene sheet is grown on the surface of the epitaxial metal film, and then the graphene sheet is separated therefrom by an acid treatment or a method utilizing a difference in reduction potential of transition metals.

41. The method for producing a graphene sheet according to claim 22, wherein the graphene sheet is grown dominantly in a pit formed on a surface of the epitaxial metal film.