Method for Forming Monolayer Graphene-Boron Nitride Heterostructures

• US 20150044367A1
• Filed: 08/06/2014
• Published: 02/12/2015
• Est. Priority Date: 08/06/2013
• Status: Active Grant

• Current Assignee: Brookhaven Science Associates, LLC (Government of the United States of America)
• Original Assignee: Brookhaven Science Associates, LLC (Government of the United States of America)
• Inventors: Sutter, Peter Werner, Sutter, Eli Anguelova
• Granted Patent: US 9,410,243 B2
• Time in Patent Office: Days
• US Class Current: 427/249.5
• CPC Class Codes: C01B 32/186 by chemical vapour deposition [CVD]
• CPC Class Codes: C01B 32/194 After-treatment
• CPC Class Codes: C01B 35/14 Compounds containing boron and nitrogen, phosphorus, sulfur, selenium or tellurium
• CPC Class Codes: C23C 16/26 Deposition of carbon only
• CPC Class Codes: C23C 16/342 Boron nitride
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 29/02 Elements
• CPC Class Codes: H01L 21/02425 Conductive materials, e.g. metallic silicides
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02433 Crystal orientation
• CPC Class Codes: H01L 21/02444 Carbon, e.g. diamond-like carbon
• CPC Class Codes: H01L 21/02499 Monolayers
• CPC Class Codes: H01L 21/02527 Carbon, e.g. diamond-like carbon
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/0259 Microstructure
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD

Abstract

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.

Claims

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;

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<sup>−

8</sup> Torr and 800°

C. and stopping exposure to ethylene exposure after approximately 400 seconds.

4. The method according to claim 1, wherein exposing the ruthenium substrate to ethylene further comprises:

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.

5. The method according to claim 1, wherein the exposures to ethylene, oxygen and borazine exposure are performed via ultrahigh vacuum chemical vapor deposition.

6. The method according to claim 1, wherein the ruthenium substrate comprises a Ru(0001) single crystal substrate.

7. The method according to claim 1, wherein the ruthenium substrate comprises an epitaxial Ru(0001) thin film on a sapphire substrate.

8. The method according to claim 1, wherein the exposure to ethylene occurs at a pressure of 1×

10<sup>−

8</sup> Torr.

9. The method according to claim 1, wherein the exposure to ethylene occurs at a temperature between 740°

C. to 800°

C.

10. The method according to claim 1, wherein the exposure to oxygen occurs at a pressure of 2×

10<sup>−

9</sup> Torr.

11. The method according to claim 1, wherein the exposure to oxygen occurs at a temperature between 610°

C. to 680°

C.

12. The method according to claim 1, wherein the exposure to borazine occurs at a pressure of 1×

10<sup>−

7</sup> Torr.

13. The method according to claim 1, wherein the step of exposure to borazine occurs at a temperature of 680°

C.

14. The method according to claim 1, wherein the ethylene is 99.999 percent pure.

15. The method according to claim 1, wherein the borazine is 99.999 percent pure.

16. The method according to claim 1, wherein the oxygen (O₂) is 99.999 percent pure O₂.

17. The method according to claim 1, wherein the ruthenium substrate comprises a polycrystalline Ru thin film on a silicon-dioxide/silicon substrate.

18. The method according to claim 1, wherein after exposing the ruthenium substrate to borazine the ruthenium substrate is covered by a graphene-boron nitride hetero structure having an abrupt interface between graphene and boron nitride.

19. 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.

20. A method for forming a graphene-boron nitride heterostructure, comprising:

exposing a ruthenium substrate to ethylene;

exposing the ruthenium substrate to oxygen after exposure to ethylene sufficient to remove C adatoms from portions of the ruthenium substrate that are not covered by graphene;

exposing the ruthenium substrate to borazine after exposure to oxygen.

21. 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.

22. The method according to claim 21, wherein the homogeneous ternary C—

B—

N alloy phases are formed at the interface between boron nitride and graphene.

23. The method according to claim 21, wherein the homogeneous ternary C—

B—

N alloy phases are formed as a uniform 2D membrane.