CHARACTERIZATION OF DIAMOND SYNTHESIZED WITH HALOGENATED METHANE IN A MICROWAVE-DISCHARGE

Diamond films were grown on Si(111) substrate using different substrate temperatures and feed gases of halogenated methane-hydrogen mixtures by microwave plasma assisted chemical vapor deposition. The deposits were characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction and transmission electron microscopy. SEM measurements showed that a well crystallized and dense nucleated diamond deposit can be more easily synthesized using halogenated methane as the feed gas than methane. The Raman spectra showed the characteristic 1331 cm-1 crystalline diamond peak and a small broad 1475 cm-1 graphitic or amorphous carbon peak. XRD measurements revealed the crystallinity of the diamond deposits as a function of deposition temperature. The majority of diamond crystals have a very high defect density comprised of {111} twins, {111} stackings, and dislocations. Fivefold multiply twinned particles have also been examined and the density of defects in these particles is generally high; however, a dramatic reduction in the defect density near the twin boundaries was observed. Using a (CHCl3+CH4)/H-2 mixture, which is a suitable gas for low-temperature diamond formation, uniform and dense diamond films were obtained by conventional cavity-mode microwave assisted CVD.