Growth of single-crystal diamond by microwave plasma CVD with high precursor utilization using cyclic gas injection and control of carbonaceous species content with optical emission spectroscopy

Single-crystal diamond was synthesized in a microwave plasma assisted chemical vapor deposition system with periodical injection of methane/hydrogen mixture in a closed reaction chamber. The gas was refreshed during a short time based on monitoring of carbonaceous species in the plasma with optical emission spectroscopy. The utilization of the precursors was increased with this strategy by about 12 times compared with the common process of the diamond growth using continuous gas flow. The structure of homoepitaxial diamond films produced in common and the periodical injection regimes was analyzed with scanning electron microscopy, atomic force microscopy, photoluminescence and Raman spectroscopy. The samples grown in the gas economy mode demonstrated a faster growth rate and smoother surface.