METHODS OF GROWING UNIFORM, LARGE-SCALE, MULTILAYER GRAPHENE FILM

• US 20150136737A1
• Filed: 05/17/2013
• Published: 05/21/2015
• Est. Priority Date: 05/17/2012
• Status: Abandoned Application

• Current Assignee: National University of Singapore
• Original Assignee: National University of Singapore
• Inventors: Loh, Kian Ping, Zhang, Kai, Castro Neto, Antonio Helio
• Application Number:
  US14/401,793
• Publication Number:
  US 20150136737A1
• Time in Patent Office: Days
• US Class Current: 216/100
• 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 2204/04 Specific amount of layers or specific thickness
• CPC Class Codes: C01B 2204/32 Size or surface area
• CPC Class Codes: C01B 32/186 by chemical vapour deposition [CVD]
• CPC Class Codes: C23C 16/26 Deposition of carbon only
• CPC Class Codes: C23C 16/45517 Confinement of gases to vicinity of substrate
• CPC Class Codes: C23C 16/56 After-treatment

Abstract

Methods of growing a multilayer graphene film (10) include flowing a weak oxidizing vapor (OV) and a gaseous carbon source (CS) over a surface (SGC) of a carbonizing catalyst (GC) in a CVD reaction chamber (2). Carbon atoms (C) deposit on the carbonizing catalyst surface to form sheets of single-layer graphene (12) upon cooling. The method generates a substantially uniform stacking of graphene layers to form the multilayer graphene film. The multilayer graphene film is substantially uniform and has a relatively large scale as compared to graphene films formed by prior-art methods.

Claims

1. A method for growing a graphene film, comprising:

disposing a carbonizing catalyst having a surface in a chemical-vapor-deposition (CVD) reaction chamber having a pressure in a range from 1 mtorr to 760 torr and a temperature in a range from 200°

C. to 1,200°

C.;

flowing a gaseous carbon source having carbon atoms, and a weak oxidizing vapor over the surface of the carbonizing catalyst, thereby causing the carbon atoms from the carbon source to deposit in a crystalized carbon-atom arrangement on the surface of the carbonizing catalyst; and

cooling the carbonizing catalyst and the crystalized carbon-atom arrangement to form a multilayer graphene film on the surface of the carbonizing catalyst.

2. The method of claim 1, further comprising separating the multilayer graphene film from the carbonizing catalyst.

3. The method of claim 2, wherein said separating comprises:

forming a protective layer over the multilayer graphene film;

etching away the carbonizing catalyst; and

removing the protective layer from the multilayer graphene film.

4. The method of claim 3, further comprising forming the protective layer from PMMA.

5. The method of claim 1, wherein the act of cooling is performed at a cooling rate in a range from about 0.1°

C. per minute to about 10°

C. per minute.

6. The method of claim 1, wherein the flowing of the gaseous carbon source is performed at a flow rate in a range from about 0.5 standard cubic centimeters per minute (“

sccm”

) to about 50 sccm.

7. The method of claim 1, wherein the weak oxidizing vapor is provided at an amount in a range from about 1% to 10% by volume in the presence of an inert gas.

8. The method of claim 1, wherein the weak oxidizing vapor consists of oxygen-containing molecules or halogen-containing molecules.

9. The method of claim 1, further comprising using plasma activation to promote dissociation the carbon source into the carbon atoms.

10. The method of claim 1, wherein the multilayer graphene film has between 2 and 20 layers of graphene.

11. The method of claim 10, wherein the multilayer graphene film has about 10 layers of graphene.

12. The method of claim 1, wherein the multilayer graphene film has a continuous surface area of at least about one square centimeter.

13. The method of claim 1, wherein the carbonizing catalyst comprises a film having a thickness in a range from about 300 nm to about 1,000 nm.

14. The method of claim 1, wherein the carbonizing catalyst comprises a film having a thickness in a range from about 0.01 mm to about 5 mm.

15. The method of claim 1, wherein the carbonizing catalyst is formed from at least one metal selected from the following group of metals:

Ni, Cu, Co, Fe, Rh, Pt, Au, Ru and Mo.

16. The method of claim 1, further comprising performing a chemical-doping step to chemically dope the multilayer graphene film.

17. The method of claim 1, wherein the gaseous carbon source includes at least one gas selected from the following group of gases:

carbon monoxide, methane, ethane, ethylene, ethanol, acetylene, propane, propylene, butane, butadiene, pentane, pentene, cyclopentadiene, hexane, cyclohexane, benzene and toluene.

18. The method of claim 1, further comprising flowing hydrogen through the reaction chamber to reduce the carbonizing catalyst.

19. The method of claim 1, wherein the surface of the carbonizing catalyst includes amorphous carbon, and further comprising oxidizing the amorphous carbon while avoiding substantially disrupting the crystalized carbon-atom arrangement on the surface of the carbonizing catalyst.

20. The method of claim 1, wherein the act of flowing a gaseous carbon source and a weak oxidizing vapor over the surface of the carbonizing catalyst is carried out for a time in the range from 1 minute to 1 hour.

21. A method for growing a multilayer graphene film, comprising the acts of:

a) disposing a carbonizing catalyst having a surface in a reaction chamber having an appropriate pressure and elevated temperature;

b) flowing a gaseous carbon source having carbon atoms over the surface of the carbonizing catalyst while subjecting the gaseous carbon source to a dissociation process, thereby causing carbon atoms from the gaseous carbon source to deposit on the surface of the carbonizing catalyst;

c) simultaneous with act b), flowing a weak oxidizing vapor in the presence of an inert gas over the surface of the carbonizing catalyst to reduce or prevent forming amorphous carbon; and

d) cooling the carbonizing catalyst and the carbon atoms thereon at a rate that forms a crystalized carbon-atom arrangement that defines stacked layers of graphene that constitute the multilayer graphene film.

22. The method of claim 21, wherein the dissociation process includes at least one of thermal activation and plasma activation.

23. The method of claim 21, wherein the elevated pressure is in a range from 1 mtorr to 760 torr.

24. The method of claim 21, wherein the elevated temperature is in a range from 200°

C. to 1,200°

C.

25. The method of claim 21, wherein the multilayer graphene film has about 10 layers.

26. The method of claim 21, wherein the multilayer graphene film has a continuous surface area of at least about 1 cm².

27. The method of claim 21, further comprising performing a chemical-doping step to chemically dope the multilayer graphene film.

28. The method of claim 21, wherein acts b) and c) are carried out for a time in the range from 1 minute to 1 hour.