Monitoring and control of RF thermal plasma diamond deposition via substrate biasing

In a RF induction thermal plasma chemical vapour deposition system the substrate is used as an electrical probe to monitor the diamond film evolution in situ. The evolving electron emission current allows us to identify the transition from the initial nucleation stage to the diamond growth stage. A direct-current bias voltage is applied to the substrate, and the polarity is adjusted in situ according to the changing growth requirements, providing a tool for controlling the diamond formation independent of the plasma source.