CATHODOLUMINESCENCE OF EPITAXIAL DIAMOND FILMS

The cathodoluminescence of epitaxial and polycrystalline diamond films was observed and intermediate emission between 2.8 and 2.4 eV was found. The epitaxial and polycrystalline diamond films were deposited by microwave plasma chemical vapour deposition (CVD) from a reactant gas consisting of hydrogen and methane, the concentration of the latter being varied from 1% to 8%. The intensity of the cathodoluminescence from both films was found to decrease with increasing CH4 concentration. The effect of electron current density suggested that the intermediate peaks between 2.8 and 2.4 eV are characteristic of epitaxial and polycrystalline films deposited at higher CH4 concentration. The quality of epitaxial film deposited at higher CH4 concentration was considered to be worse than that at lower CH4 concentration. The peak of the cathodoluminescence of boron-doped epitaxial film was found to be at 2.4 eV, which suggests the existence of defects characteristic of CVD methods.