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.