Fabrication of large-area hexagonal boron nitride thin films
A hexagonal boron nitride thin film is grown on a metal surface of a growth substrate and then annealed. The hexagonal boron nitride thin film is coated with a protective support layer and released from the metal surface. The boron nitride thin film together with the protective support layer can then be transferred to any of a variety of arbitrary substrates.
1. A method for fabricating a hexagonal boron nitride film, comprising:
providing a growth substrate including a metal surface;
growing a hexagonal boron nitride film on the metal surface;
annealing the hexagonal boron nitride film;
coating the hexagonal boron nitride film with a protective support layer; and
releasing the whole hexagonal boron nitride film together with the protective support layer from the metal surface.
2. The method of claim 1 , wherein the hexagonal boron nitride film is deposited on the metal surface via chemical vapor deposition at a temperature less than 400° C.
3. The method of claim 2 , wherein the chemical vapor deposition is carried out at ambient pressure.
4. The method of claim 2 , wherein the chemical vapor deposition is carried out at a pressure of at least about 50 kPa.
5. The method of claim 1 , wherein the hexagonal boron nitride film is annealed at a temperature in a range from about 900° C. to about 1100° C.
6. The method of claim 1 , further comprising applying the hexagonal boron nitride film and the protective support layer coating to a target substrate.
7. The method of claim 6 , further comprising removing the protective support layer from the hexagonal boron nitride film after application to the target substrate.
8. The method of claim 7 , further comprising doping at least one region of the hexagonal boron nitride film to produce at least one p- or n-type region for a device.
9. The method of claim 7 , further comprising intercalating at least one other type of molecule into the hexagonal boron nitride film.
10. The method of claim 1 , wherein the metal surface comprises at least one of nickel, platinum, copper, ruthenium, iron, cobalt, and molybdenum.
11. The method of claim 10 , wherein the metal surface comprises nickel.
12. The method of claim 10 , wherein the growth substrate comprises silicon with a silica surface coating, and wherein the metal surface is formed over the silica surface coating.
13. The method of claim 10 , further comprising providing the metal surface on the growth substrate via a deposition method selected from evaporation, sputtering and electro-chemical deposition.
14. The method of claim 13 , further comprising patterning the metal surface via lithography.
15. The method of claim 1 , wherein the hexagonal boron nitride film is deposited on the metal surface via chemical vapor deposition using a precursor selected from at least one of borazine and B-trichloroborazine ((ClBNH) 3 ).
16. The method of claim 15 , wherein the precursor is borazine and the hexagonal boron nitride film is formed when the borazine contacts the metal surface at a temperature of about 400° C. and dehydrogenates.
17. The method of claim 15 , further comprising annealing the hexagonal boron nitride film at or above 1000° C. on the metal surface.
18. The method of claim 1 , wherein the protective support layer comprises at least one of polymethylmethacrylate, polydimethylsiloxane, polyethylene terephthalate, and polyethylene naphthalate.
19. The method of claim 1 , wherein the metal surface is etched to release the hexagonal boron nitride film and the protective support layer.
20. The method of claim 19 , wherein the hexagonal boron nitride film has a thickness of 1 nm to 50 nm and covers an area of at least about 1 cm 2 .