Cubic boron nitride crystallites grown by laser-enhanced plasma chemical vapour deposition

Cubic boron nitride (CBN) crystallites have been grown by plasma enhanced chemical vapour deposition from BCl 3 +NH 3 +H 2 +Ar under the irradiation of an ArF excimer laser at 193 nm, at substrate temperatures of between 500 and 900 degrees C, on Si(100) surfaces; the energy density for a laser pulse was 18-24 mJ cm -2 . The lattice parameter a of the polycrystalline part, measured by transmission electron diffractometry, was found to be 3.62 A, which is in fairly good agreement with the standard data available, i.e. 3.6158 A. A few micrometre-sized crystallites, with a morphology originated from a four-fold symmetry in the crystal structure, were found by scanning electron microscopy; these are considered to be CBN crystallites with their (100) planes parallel to the Si(100) according to the law of Bravais, being consistent with the recent report on heteroepitaxial growth of CBN film on the Si(100) by a laser-ablation method.