Borophenes, boron layer allotropes and methods of preparation
A method of preparing an atomically-dimensioned elemental boron allotrope includes providing a substrate at a temperature greater than about 200° C.; generating elemental boron vapor from a solid elemental boron source; and contacting said substrate with said boron vapor for at least one of a rate and at a pressure sufficient to deposit on said substrate a boron allotrope comprising an elemental boron layer comprising a boron atomic thickness dimension, said method under negative pressure.
1. A method of preparing an atomically-dimensioned elemental boron allotrope, said method comprising:
providing a substrate at a temperature greater than about 200° C.;
generating elemental boron vapor from a solid elemental boron source; and
contacting said substrate with said boron vapor for at least one of a rate and at a pressure sufficient to deposit on said substrate a boron allotrope comprising an elemental boron layer comprising a boron atomic thickness dimension, said method under negative pressure.
2. The method of claim 1 wherein said substrate comprises Ag.
3. The method of claim 2 wherein said substrate comprises single crystal Ag(111).
4. The method of claim 3 wherein said allotrope comprises at least one of a homogeneous boron phase and a striped boron phase.
5. The method of claim 4 wherein said substrate temperature is about 400° C. to about 750° C.
6. The method of claim 5 wherein a higher substrate temperature within said temperature range promotes said striped boron phase.
7. The method of claim 1 wherein said rate of deposition is about 0.01 to about 0.1 layer of elemental boron per minute.
8. The method of claim 7 wherein a greater deposition rate within said deposition rate range promotes said homogeneous boron phase.
9. The method of claim 1 wherein said solid boron source is about 99.9999% pure.
10. The method of claim 9 wherein said deposited boron allotrope is absent carbon and oxygen.
11. The method of claim 1 at a pressure of about 10 −9 to about 10 −11 mBar.
12. A method of preparing an atomically-dimensioned elemental boron allotrope monolayer, said method comprising:
providing a silver substrate at a temperature of about 400° C. to about 750° C.;
generating elemental boron vapor from a solid elemental boron source; and
contacting said substrate with said boron vapor under a pressure at least as low as about 10 −9 mBar, said contact a rate sufficient to deposit on said substrate a boron allotrope comprising an elemental boron monolayer comprising a boron atomic thickness dimension, whereby said method does not provide a boron compound or a boron alloy.
13. The method of claim 12 wherein said substrate comprises single crystal Ag(111).
14. The method of claim 13 wherein said allotrope comprises at least one of a homogeneous boron phase and a striped boron phase.
15. The method of claim 14 wherein said substrate temperature is about 450° C. to about 700° C.; and said rate of deposition is about 0.01 to about 0.1 layer of elemental boron per minute.
16. The method of claim 15 wherein a higher substrate temperature within said temperature range promotes said striped boron phase.
17. The method of claim 15 wherein a greater deposition rate within said deposition rate range promotes said homogeneous boron phase.
18. The method of claim 12 wherein said solid boron source is about 99.9999% pure, and said deposited boron allotrope is absent carbon and oxygen.