Amorphous carbon films in direct current magnetron sputtering from regenerative sooting discharge

We present results of carbon coatings on metal substrates in cylindrical hollow cathode (CHC) direct current magnetron sputtering. This is a new technique for making amorphous carbon films by CHC magnetron sputtering from a regenerative sooting discharge. The carbon films are deposited on Cu and Al substrates in a Ne atmosphere and compared with the films of carbon soot on the same materials produced from a conventional 80A arc discharge between graphite electrodes in a He background gas. Raman spectroscopy reveals the existence of graphite and diamond-like structures from the arc discharge while in CHC magnetron sputtering, graphite-like structures are dominant. X-ray diffraction data of samples from the arc discharge show nano-size precipitates of Al4C3 of rhombohedral and hexagonal form for the aluminium sample and probable formation of diamond and hexagonal carbon in copper whilst in magnetron sputtering we obtain amorphous carbon films. Scanning electron microscope images of the surface show a collection of loose agglomerates of carbon particles in the arc discharge whereas, for magnetron sputtering, structures are regular with smooth edges and fine grains.

► A new technique of amorphous carbon films in hollow cathode magnetron sputtering. ► Results are compared with sublimation of graphite in arc discharge on Cu and Al. ► Raman, FTIR, emission spectroscopy, XRD and SEM are used as diagnostic techniques. ► sp2 bonding dominant in sputtering while in sublimation both sp2 and sp3 present. ► Online emission gives atomic species in sputtering and molecular in sublimation.