Diamond volume crystal growth in HF-CVD and monitoring gas phase with laser absorption spectroscopy

In hot-filament CVD we synthesized single diamond crystals up to 100 μm in diameter [1]. In order to enhance growth rate and impede growth defects, it is intended to employ a new gas feeding system. This allows CH 4 to be separately applied from H 2 to the reactor locally at the substrate position. The effect of this concept on the gas phase was analyzed by Infrared Tuneable Diode Laser Absorption Spectroscopy (IR-TDLAS). The changes in species concentrations of CH 4 , CH 3 and C 2 H 2 with the substrate distance from filaments as well as first growth results are shown.