The structural phases of non-crystalline carbon prepared by physical vapour deposition

The structure of non-crystalline carbon films produced using physical vapour deposition is studied as a function of ion impact energy and substrate temperature. The average ion energy was varied from 10 eV to 820 eV using magnetron sputtering and cathodic arc deposition systems while the substrate temperature was varied from room temperature to 640 °C. The intrinsic stress, film density and through-film electrical resistance were mapped in the ion energy–temperature plane. These contour plots show the deposition conditions which give rise to stressed tetrahedral amorphous carbon (ta-C), stress relieved ta-C and lower density films with a variety of structural forms. Electron microscopy revealed that the microstructure of the low-density forms ranges from highly disordered to various types of oriented graphitic material. The microstructure is determined by the local structural rearrangements that occur due to ion impacts on the picosecond timescale (thermal spikes) and slower relaxation processes which depend on the substrate temperature.