Influence of carbon content on the crystallographic structure of boron carbide films

Boron carbide thin films were synthesised by laser-assisted chemical vapour deposition (LCVD), using a CO(2) laser beam and boron trichloride and methane as precursors. Boron and carbon contents were measured by electron probe microanalysis (EPMA). Microstructural analysis was carried out by Raman microspectroscopy and glancing-incidence X-ray diffraction (GIXRD) was used to study the crystallographic structure and to determine the lattice parameters of the polycrystalline films. The rhombohedral-hexagonal boron carbide crystal lattice constants were plotted as a function of the carbon content, and the non-linear behaviour observed was interpreted on the basis of the complex structure of boron carbide. (C) 2000 Elsevier Science S.A. All rights reserved.