Dependence of the growth rate, quality, and morphology of diamond coatings on the pressure during the CVD-process in an industrial hot-filament plant

The pressure dependence of the growth rate, quality and morphology of CVD-diamond films in an industrial hot-filament plant (CC800D) were investigated by SEM and Raman. Additionally, the concentration of atomic hydrogen near the filament was determined via a calorimetric measurement method. At a substrate temperature of 850 °C the smallest growth rate (0.1 μm/h) and the best quality of diamond coatings were obtained at the pressure with the highest hydrogen concentration (20 mbar). The growth rate increases strongly with decreasing pressure and achieves the maximum value of 0.7 μm/h at 3 mbar. At the same time the diamond coating quality decreases.