Method for forming monolayer graphene-boron nitride heterostructures
A method for fabricating monolayer graphene-boron nitride heterostructures in a single atomically thin membrane that limits intermixing at boundaries between graphene and h-BN, so as to achieve atomically sharp interfaces between these materials. In one embodiment, the method comprises exposing a ruthenium substrate to ethylene, exposing the ruthenium substrate to oxygen after exposure to ethylene and exposing the ruthenium substrate to borazine after exposure to oxygen.
1. A method for forming a graphene boron nitride interface, comprising:
exposing a ruthenium substrate to ethylene;
exposing the ruthenium substrate to oxygen after exposure to ethylene;
stopping exposure to oxygen when C adatoms have been substantially eliminated from portions of the ruthenium substrate that are not covered by monolayer graphene domains; and
exposing the ruthenium substrate to borazine after exposure to oxygen.
2. The method according to claim 1 , further comprising:
stopping exposure to ethylene upon partial coverage of the ruthenium substrate with monolayer graphene domains.
3. The method according to claim 1 , wherein exposing the ruthenium substrate to ethylene further comprises:
exposure to ethylene under 10 −8 Torr and 800° C. and stopping exposure to ethylene exposure after approximately 400 seconds.
4. The method according to claim 1 , wherein the exposures to ethylene and borazine exposure are performed via ultrahigh vacuum chemical vapor deposition.
5. The method according to claim 1 , wherein the ruthenium substrate comprises a Ru(0001) single crystal substrate.
6. The method according to claim 1 , wherein the ruthenium substrate comprises an epitaxial Ru(0001) thin film on a sapphire substrate.
7. The method according to claim 1 , wherein the exposure to ethylene occurs at a pressure of 1×10 −8 Torr.
8. The method according to claim 1 , wherein the exposure to ethylene occurs at a temperature between 740° C. to 800° C.
9. The method according to claim 1 , wherein the exposure to oxygen occurs at a pressure of 2×10 −9 Torr.
10. The method according to claim 1 , wherein the exposure to oxygen occurs at a temperature between 610° C. to 680° C.
11. The method according to claim 1 , wherein the exposure to borazine occurs at a pressure of 1×10 −7 Torr.
12. The method according to claim 1 , wherein the step of exposure to borazine occurs at a temperature of 680° C.
13. The method according to claim 1 , wherein the ethylene is 99.999 percent pure.
14. The method according to claim 1 , wherein the borazine is 99.999 percent pure.
15. The method according to claim 1 , wherein the oxygen (O 2 ) is 99.999 percent pure O 2 .
16. The method according to claim 1 , wherein after exposing the ruthenium substrate to borazine the ruthenium substrate is covered by a graphene-boron nitride heterostructure having an abrupt interface between graphene and boron nitride.
17. The method according to claim 1 , wherein after exposing the ruthenium substrate to borazine the ruthenium substrate is covered by homogeneous ternary C—B—N alloy phases having a non-abrupt interface between graphene and boron nitride.
18. A method for synthesizing tunable homogeneous ternary C—B—N alloy phases, comprising:
exposing a ruthenium substrate to ethylene sufficient to form the homogeneous ternary C—B—N alloy phases;
exposing the ruthenium substrate to oxygen after exposure to ethylene;
exposing the ruthenium substrate to borazine after exposure to oxygen sufficient to form the homogeneous ternary C—B—N alloy phases, wherein the homogeneous ternary C—B—N alloy phases are formed as a uniform 2D membrane.
19. The method according to claim 18 , wherein the homogeneous ternary C—B—N alloy phases are formed at the interface between boron nitride and graphene.