Influence of boron carbide on properties of CVD-diamond thin films at various deposition pressures

Microcrystalline boron-doped diamond (BDD) films are synthesized on the silicon substrate by the hot-filament chemical vapor deposition method under the gas mixture of hydrogen and methane in the presence of boron carbide (B4C) placed in front of filaments. The observed results of scanning electron microscopy, Raman spectroscopy and X-ray diffraction show the morphologies. Microstructures for various deposition pressures of as-grown diamond films are found to be dependent on the change of deposition pressure. These results reveal that with the increase of deposition pressure, resistivity decreases and increase in the grain size is noted in the presence of B4C. Resistivity shows a sudden fall of about three orders of magnitude by the addition of boron in the diamond films. This is due to the crystal integrity induced by B-atoms in the structure of diamond in the presence of B4C. These results are also significant for the conventional applications of BDD materials. The effects of deposition pressure on the overall films morphology and the doping level dependence of the diamond films have also been discussed.

► Diamond thin films grown on Si at various gas flow rates in modified HFCVD system. ► XRD, SEM and Raman spectroscopy used for internal fiber texture, surface morphology. ► Randomly oriented grains having dominant (111) facet with sharp grain boundaries. ► The addition of boron caused an abrupt fall of resistivity from 108 to 105 Ω cm. ► Present films with low resistivity are useful as semiconductor and/or insulating materials.