Growth of Diamond from Atomic Hydrogen and a Supersonic Free Jet of Methyl Radicals

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Abstract
The growth of small (∼10-micrometer) diamond particles (on 0.1-or 0.25-micrometer seed crystals) using an effusive glow discharge nozzle for H·and a separate supersonic pyrolysis jet for ·CH3 is reported. Laser micro-Raman, scanning electron microscopy, and x-ray photoelectron spectroscopy data are presented as evidence that well-crystallized diamond is indeed formed. Resonant multiphoton ionization spectroscopy is used as a diagnostic for the gas-phase chemistry indicating that the radical sources are clean and quantitative and that there is no detectable interconversion of ·CH3 to C2H2 under the conditions of the experiment. Diamond growth is found at substrate temperatures greater than or equal to 650°C with no marked increase in the rate of growth up to 850°C. Acetylene does not give good quality diamond under similar conditions.