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 BF(3)-H(2)-N(2) 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 H(2) in N(2). A large decrease of the BF(3) and H(2) concentrations was achieved by increasing the gas flow rate of N(2) and keeping the BF(3) and H(2) flow rates constant and the mono- and few-atomic-layered BN sheets were obtained at the BF(3), H(2) and N(2) 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.