Laser-assisted CVD of boron carbide at atmospheric pressure

In a previous study, laser assisted chemical vapour deposition of boron car bide thin films was carried out from a gas mixture of BCl3, CH4, H-2 and ar gon at a working pressure of 133 mbar, using a cw CO2 laser. This paper foc uses on the deposition of rhombohedral boron carbide at atmospheric pressur e from the same precursor gases. The deposition of single phase boron carbi de films was achieved at laser irradiances of 90 W/cm(2). At higher irradia nce values, unlike deposition at lower pressure, the films present a dark c entral region with whisker-like morphology due to co-deposition of boron ca rbide and disordered graphite. (C) 1999 Elsevier Science B.V. All rights re served.