Cubic boron nitride synthesis in low‐density supersonic plasma flows

We report on the growth of cubic boron nitride films on {100} silicon using a low density, supersonic plasma jet generated by a direct‐current arc discharge expanded to low pressures. The arc discharge was operated on source gas mixtures of nitrogen and argon, with boron trichloride injected downstream of the expansion nozzle. The films were analyzed by infrared absorption and x‐ray photoelectron spectroscopy. Phase selectivity was obtained by the application of a negative bias to the substrate so as to bombard the surface with energetic ions during deposition. The deposition process was found to be highly sensitive to substrate temperature and substrate bias voltage.