THE GROWTH OF DIAMOND USING HALOGENATED METHANE

Diamond films were grown on Si(111) substrates using different substrate temperatures, feed gases and relative concentrations of halogenated methane-hydrogen mixtures, by microwave plasma assisted chemical vapor deposition (CVD). The films were characterized by scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). 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 surface topography changed from faceted, microcrystalline to spherulitic polycrystalline with increasing chloroform concentration. The Raman spectrum 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 chloroform concentration. Using a (CHCl3 + CH4)-H-2 mixture, which is a suitable gas for low-temperature diamond formation, high-quality, uniform and dense diamond films were obtained by conventional cavity-mode microwave assisted CVD at temperatures as low as 400-degrees-C.