Method and system for graphene formation
A method of forming graphene includes placing a substrate in a processing chamber and introducing a cleaning gas including hydrogen and nitrogen into the processing chamber. The method also includes introducing a carbon source into the processing chamber and initiating a microwave plasma in the processing chamber. The method further includes subjecting the substrate to a flow of the cleaning gas and the carbon source for a predetermined period of time to form the graphene.
1. A method of forming graphene, the method comprising:
placing a growth substrate in a processing chamber;
introducing a cleaning gas including hydrogen and nitrogen into the processing chamber;
introducing a carbon source into the processing chamber;
initiating a microwave plasma in the processing chamber;
forming cyano radicals from the carbon source and the nitrogen in the processing chamber in the presence of the microwave plasma;
cleaning the growth substrate with the cyano radicals formed in the processing chamber; and
subjecting the growth substrate to the microwave plasma and a flow of the cleaning gas and the carbon source for a predetermined period of time to form the graphene characterized by grains ranging in size between 100 μm and 300 μm; with the microwave plasma, while forming the graphene having a maximum temperature at the center of the microwave plasma, wherein the maximum temperature is 425° C. and a temperature of the growth substrate is less than the maximum temperature.
2. The method of claim 1 wherein the graphene consists of a single monolayer.
3. The method of claim 1 wherein the graphene is characterized by a measurement area in a unit of length squared and a height variation measured in the unit of length, wherein the measurement area is between 4 nm 2 and 100 nm 2 , and a ratio of the height variation to the measurement area is less than 10% per unit of length.
4. The method of claim 3 wherein the ratio is less than 1% per unit of length.
5. The method of claim 3 wherein the ratio of the height variation to the measurement area is measured at room temperature.
6. The method of claim 1 wherein introducing the cleaning gas and introducing the carbon source are performed concurrently.
7. The method of claim 1 wherein the carbon source comprises methane.
8. The method of claim 1 wherein the growth substrate comprises a copper substrate.
9. The method of claim 8 wherein the copper substrate is a single crystal copper substrate.
10. The method of claim 9 wherein the single crystal copper substrate is a single crystal (100) substrate.
11. The method of claim 9 wherein the single crystal copper substrate is a single crystal (111) substrate.
12. The method of claim 8 further comprising at least one of etching or smoothing the copper substrate.
13. The method of claim 1 further comprising removing native oxide present on the growth substrate after initiating the microwave plasma.
14. The method of claim 13 wherein introducing the carbon source is performed prior to removing the native oxide.
15. The method of claim 1 wherein the growth substrate is a polycrystalline copper foil and the graphene is characterized by a first Raman peak associated with a 2D-band mode and a second Raman peak associated with a G-band mode, wherein a ratio of the first Raman peak to the second Raman peak is about three.
16. The method of claim 1 wherein the growth substrate is a polycrystalline copper foil and the graphene is characterized by a Raman spectra having a G-band peak less than a G-band peak of 1000° C. grown graphene.
17. The method of claim 1 wherein the growth substrate is a polycrystalline copper foil and the graphene is characterized by a Raman spectra having a 2D-band peak measured in wavenumbers less than a 2D-band peak of 1000° C. grown graphene.