Novel superhard BC10N synthesized by microwave plasma CVD

Abstract

Microwave Plasma Chemical Vapor Deposition (MPCVD) was used to synthesize novel superhard BC10N on silicon substrates. Feedgas mixtures of H2, CH4, N2, and B2H6 were used for a range of systematically varied microwave power, chamber pressure, and flow rate conditions. Optical Emission Spectroscopy (OES) was used to guide the synthesis of BC10N. Plasma optical emission from the C2 peak increases with pressure up to 80 Torr and saturates in the 80–100 Torr range. The C2 emission also follows the same trend, growing non-linearly with increasing microwave power (for fixed chamber pressure of 30 Torr). The presence of abundant C2 in the plasma is advantageous under specific growth conditions to produce superhard carbon-rich BC10N, a material that has been theoretically predicted but not yet synthesized. Findings obtained from X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) elucidate the existence of BC, CN, BN, and B-N-C bonding in the synthesized coating. Nanoindentation hardness measurements are within the superhard regime, showing an average hardness of 63 GPa.