Diamond thin films were deposited on silicon by microwave plasma-assisted chemical vapour deposition in a tubular reactor using a continuous wave mode as well as a pulse mode. A process gas mixture of methane diluted in hydrogen was used. The pulse mode experiments were performed in a parameter range 200–400 W microwave average power, 400–800 W microwave peak power and 200 Hz–5 kHz pulse repetition rate. It has been demonstrated that substrate temperature, growth rate and film quality, as reflected in surface morphology and Raman patterns, are affected in first order only by the microwave average power input, similar to the continuous wave mode. In the parameter range investigated, microwave peak power and pulse repetition rate have only a small effect on deposition conditions and film quality.
