Methods of forming graphene single crystal domains on a low nucleation site density substrate
View Patent ↗A method of forming graphene single crystal domains on a carbon substrate is described.
1. A method of forming a graphene single crystal domain on a substrate comprising a metal, comprising:
a) contacting the substrate with a passivating gas to thereby decrease the number of nucleating sites on the substrate by at least 50% to thereby create a low nucleation site density substrate, wherein the passivating gas comprises O 2 , sulfur, selenium, or a combination thereof, and wherein the passivating gas is provided at a pressure of from 1×10 −3 to 760 Torr; and
b) contacting the low nucleation site density substrate with a working gas at a first elevated temperature, wherein the working gas is provided at a pressure of from 1×10 −6 Torr to 0.1 Torr, and wherein the working gas comprises a hydrocarbon gas;
thereby forming a graphene single crystal domain on the low nucleation site density substrate.
2. The method of claim 1 , wherein the substrate comprises a metal foil.
3. The method of claim 1 , wherein the substrate comprises a dielectric substance coated with a metal.
4. The method of claim 1 , wherein the substrate comprises a wafer coated with a metal.
5. The method of claim 1 , wherein the method further comprises an annealing step before said contacting steps.
6. The method of claim 5 , wherein the annealing step comprises contacting the substrate with an annealing gas at a second elevated temperature.
7. The method of claim 6 , wherein annealing gas comprises hydrogen.
8. The method of claim 6 , wherein the substrate is contacted with the annealing gas for from 1 second to 100 minutes.
9. The method of claim 6 , wherein the annealing gas is provided at a pressure of from 1×10 −6 to 760 Torr.
10. The method of claim 6 , wherein the second elevated temperature is at least 1000° C.
11. The method of claim 1 , wherein the substrate is contacted with the passivating gas for from 1 second to 20 minutes.
12. The method of claim 1 , wherein the passivating gas is flowed at a rate of from 1 to 10,000 sccm.
13. The method of claim 1 , wherein the substrate is contacted with the passivating gas at a temperature of at least 20° C.
14. The method of claim 1 , wherein the passivating gas comprises O 2 .
15. The method of any claim 1 , wherein the substrate is contacted with the working gas for from 1 to 800 minutes.
16. The method of claim 1 , wherein the working gas is flowed at a rate of from 1 to 10,000 sccm.
17. The method of claim 1 , wherein the first elevated temperature is from 300° C. to 1080° C.
18. The method of claim 1 , wherein the working gas comprises one or more of the following: ethylene, acetylene, methane, benzene, toluene, ethane, hexane, heptanes, and octane.
19. The method of claim 1 , wherein the working gas comprises methane.
20. The method of claim 1 , wherein the number of nucleation sites is decreased by at least 75%.
21. The method of claim 1 , wherein the density of nucleation sites on the low nucleation density substrate is less than 1000 mm 2 .
22. The method of claim 1 , wherein the density of nucleation sites on the low nucleation density substrate is less than 100 mm 2 .
23. The method of claim 1 , wherein the substrate comprises copper.
24. The method of claim 23 , wherein the copper is oxygen rich.
25. The method of claim 23 , wherein the copper is substantially oxygen free.
26. The method of claim 1 , wherein the graphene single crystal domain is at least 100 micrometers in size.
27. The method of claim 1 , wherein the graphene single crystal domain is at least 1 centimeter in size.
28. The method of claim 1 , wherein the graphene single crystal domain density on the substrate is 100 mm −2 or less.
29. The method of claim 1 , wherein the graphene single crystal domain is dendritic in shape.
30. A method of forming a graphene single crystal domain, comprising:
contacting a surface of an oxygen rich substrate having nucleation sites with a working gas at an elevated temperature, wherein the surface of the oxygen rich substrate comprises 10 −2 atomic % oxygen or more;
wherein the oxygen rich substrate comprises a metal;
wherein the working gas comprises a hydrocarbon gas;
wherein the density of nucleation sites on the surface of the oxygen rich substrate is less than 100 mm −2 ;
thereby forming a graphene single crystal domain on the surface of the oxygen rich substrate.