Catalyst-free growth of mono-and few-atomic-layer boron nitride sheets by chemical vapor deposition

Boron nitride (BN) is a wide bandgap semiconductor with a structure analogous to graphite. Mono-and few-atomic-layer BN sheets have been grown on silicon substrates by microwave plasma chemical vapor deposition from a gas mixture of BF₃-H₂-N₂ without using any catalysts. Growth of the BN sheets can be ascribed to the etching effects of the fluorine-containing gases and the thickness control down to mono-and few-atomic-layers was realized by decreasing the concentrations of BF ₃ and H₂ in N₂. A large decrease of the BF ₃ and H₂ concentrations was achieved by increasing the gas flow rate of N₂ and keeping the BF₃ and H₂ flow rates constant and the mono-and few-atomic-layered BN sheets were obtained at the BF₃, H₂ and N₂ flow rates of 3, 10, and 1200 sccm. The present mono-and few-atomic-layer BN sheets are promising for applications in catalyst supports, composites, gas adsorption, nanoelectronics, etc.