Suspended Thin Film Structures

• US 20110200787A1
• Filed: 01/25/2011
• Published: 08/18/2011
• Est. Priority Date: 01/26/2010
• Status: Abandoned Application

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Zettl, Alexander, Regan, William R., Aleman, Benjamin J.
• Application Number:
  US13/013,645
• Publication Number:
  US 20110200787A1
• Time in Patent Office: Days
• US Class Current: 428/138
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H01J 37/20 Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support
• CPC Class Codes: Y10T 428/24331 including nonapertured component

Abstract

Disclosed is a method of preparing a support structure suitable for use, e.g., in microscopic studies, comprising a free standing atomically thin film (e.g. graphene) suspended across an opening in the support structure. The method in one aspect comprises the steps of preparing a thin film which is an atomically thin film (e.g., graphene) on a surface of a solid substrate to form a graphene-layered substrate; attaching the graphene layer to a hole-containing support mesh; removing the solid support, thereby transferring the graphene layer from the substrate to the carbonaceous hole-containing layer on the support mesh; and then removing contaminants to obtain said structure. In another aspect, the present method does not involve a transfer, but comprises a lithography and etching process in which the atomically thin layer is applied to a support which is marked with a lithographic pattern and selectively etched, leaving the free standing film.

Claims

1. A method of preparing a structure comprising an atomically thin film (“

ATF”

) suspended across at least one hole in a support mesh, comprising the steps of;

(a) obtaining an ATF layer on a surface of a solid substrate;

(b) attaching the ATF layer on the solid substrate from step (a) to a support mesh having at least one hole therein;

(c) removing the solid substrate, leaving the ATF layer from the substrate attached to the support mesh and suspended across at least on hole in the support mesh; and

(d) removing any contaminants remaining on the ATF layer, to obtain said structure.

2. The method of claim 1 where the atomically thin film (“

ATF”

) layer is essentially single layer graphene.

3. The method of claim 1 where the atomically thin film (“

ATF”

) layer is selected from the group consisting of graphene, BN, BxCyNz, and thin film dichalcogenides.

4. The method of claim 1 where the solid substrate is a metallic material which contains copper, nickel, silver, ruthenium, palladium, platinum, or other metals with low carbon solubility.

5. The method of claim 4 where the substrate contains copper.

6. The method of claim 5 where the substrate is elemental copper.

7. The method of claim 1 where the solid substrate contains silicon.

8. The method of claim 1 where the support mesh comprises a carbonaceous layer, such as holey carbon on an underlying grid.

9. The method of claim 8 where the holey carbon is amorphous carbon.

10. The method of claim 8 where the holey carbon has a nominal sieve opening size of between 100 nm and 100 μ

m.

11. The method of claim 8 where the removing of the solid substrate step comprises the step of etching.

12. The method of claim 8 where the step of attaching the atomically thin film layer to the carbonaceous hole-containing layer comprises the step of adding a solvent to a junction between said atomically thin film layer and carbonaceous hole-containing layer.

13. The method of claim 12 where the solvent is a lower alkyl alcohol.

14. The method of claim 13 where the lower alkyl alcohol is isopropyl alcohol.

15. The method of claim 1 where the step of obtaining an ATF layer comprises the step of applying the ATF layer by chemical vapor deposition on a copper foil.

16. A structure for use in preparing a support structure for a suspended single layer atomically thin film, comprising:

(a) an essentially single layer atomically thin film layer on a substrate; and

(b) a hole-containing layer on a support mesh attached to said atomically thin film layer by bonding of the atomically thin film layer to the hole-containing layer.

17. The structure of claim 16 where the support mesh is gold.

18. The structure of claim 16 where the substrate contains an etchable metal.

19. The structure of claim 18 where the etchable metal is copper.

20. The structure of claim 16 where the hole-containing layer is holey amorphous carbon.

21. The structure of claim 20 where the holey amorphous carbon has a nominal sieve opening of between 100 nm and 100 μ

m.

22. A method of preparing a structure comprising an atomically thin film (“

ATF”

) suspended across at least one hole in a support mesh, comprising the steps of;

(a) obtaining an ATF layer on a surface of a solid substrate, said solid substrate having a first ATF layered side and an opposing second side;

(b) preparing an etching pattern on the opposing second side of the substrate, the etching pattern comprising defined portions of the substrate to be etched;

then

(c) etching the defined portions to remove substrate, leaving the ATF layer suspended across at least one hole formed by etched portions and leaving unetched portions forming a support mesh; and

then

(d) removing contaminants to obtain said structure having an atomically thin film layer suspended across at least one hole in a support mesh.

23. The method of claim 22 where the step of preparing an etching pattern comprises steps of coating a resist on the opposing second side of the substrate and exposing the resist to an agent that passes through a mask which forms said pattern, and then removing the resist to form said defined portions to be removed.

24. The method of claim 22 where the resist is a positive photoresist.

25. The method of claim 22 further comprising steps of applying a resist to the ATF layer and exposing the photoresist to radiation, and removing exposed portions of the photoresist prior to said etching.

26. The method of claim 25 where the ATF layer is essentially single layer graphene.

27. The method of claim 25 where the atomically thin film layer is selected from the group consisting of graphene, BN, BxCyNz, and thin film dichalcogenides.

28. The method of claim 25 where the solid substrate is a metallic material which contains copper, nickel, silver, ruthenium, palladium, platinum, or other metals with low carbon solubility.

29. The method of claim 28 where the substrate contains copper.

30. The method of claim 29 where the substrate is elemental copper.

31. The method of claim 25 where the solid substrate contains silicon.

32. The method of claim 22 where the support mesh comprises a carbonaceous layer, such as holey carbon.

33. The method of claim 32 where the holey carbon is amorphous carbon.

34. The method of claim 33 where the holey carbon has a nominal sieve opening size of between 100 nm and 100 μ

m.

35. The method of claim 22 where multiple structures are prepared simultaneously from the same solid substrate.

36. The method of claim 22 wherein the step of obtaining an ATF layer on a surface of a solid substrate comprises the step of chemical vapor deposition.