Synthesis and Characterization of Free-Standing Boron Carbon Nitride Nanosheets (Bcnns) in Inductively Coupled Plasma

A bottom-up synthesis route for boron carbon nitride nanosheets (BCNNS) in radio-frequency inductively coupled plasma (RF-ICP) is shown. Ammonia borane is used as the boron and nitrogen source, methane as the carbon source with nitrogen gas compensatings for recombined atomic nitrogen. Electron microscopy images for BCNNS show two-dimensional structures having lateral sizes of 100-200 nm (average 110 nm) and 1.1 - 3.7 nm (3-10 atomic layers) sheet thickness. The 2D structures show non-uniform layer stacking not characteristic of BNNS or graphene. The presence of the dislocation-type defects causing non-uniform stacking may be associated to a segregation of boron-nitride and carbon-carbon phases, this being a strong indication that the generated material is BCNNS. SAED patterns show characteristic planes of BCNNS. Further, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy suggest the quasi-uniform ratios of the three elements comprising BCNNS. The presence of these elements and the sp 2 hybridization of the bonding are studied using electron energy loss spectroscopy. We further use FTIR to show the presence of the B−N/B=N, C−N/C=N, and C−B/C=B groups, and Raman spectroscopy to study the graphitization of the material. The optical band gap of BCNNS material was estimated using Tauc method to be 2.6 eV. Decreasing the methane flow rate results in the formation of segregated phases and in the occurrence of other band gap energies in the same sample. These findings indicate inductively coupled plasmas to be a practical technique for scalable BCNNS semiconductor synthesis in a powder form at an industrial scale.