Laser-assisted CVD of boron carbide at atmospheric pressure

In a previous study, laser assisted chemical vapour deposition of boron carbide thin films was carried out from a gas mixture of BCl3, CH4, H2and argon at a working pressure of 133 mbar, using a cw CO2 laser. This paper focuses on the deposition of rhombohedral boron carbide at atmospheric pressure from the same precursor gases. The deposition of single phase boron carbide films was achieved at laser irradiances of 90 Wrcm2. At higher irradiance values, unlike deposition at lower pressure, the films present a dark central region with whisker-like morphology due to co-deposition of boron carbide and disordered graphite. q1999 Elsevier Science B.V. All rights reserved