Fullerene formation during production of chemical vapor deposited diamond

We report a novel method for fullerene formation during diamond synthesis via a hot filament, chemical vapor deposition (CVD) procedure. The fullerenes occur in the soot that forms as a by-product on the edges and rear surface of the substrate holder, where the temperature does not favor diamond deposition. Mass spectrometry of the soot shows a peak having a mass to charge ratio corresponding to C₆₀. From typical concentrations of gaseous species in the diamond-growing CVD chamber, we conclude that hydrocarbon species such as CH₃ or C₂H₂ may be the precursors for the fullerene in the CVD chamber. The atomic hydrogen in the gaseous species is believed to play an important role in removing the hydrogen from hydrocarbon to form the all-carbon fullerene. Our observations also suggest that fullerenes produced in the CVD diamond growth chamber play a role in diamond nucleation on foreign substrates.