Effect of substrate bias in amorphous carbon films having embedded nanocrystallites

The effect of substrate bias on the structural, morphological, electrical and mechanical properties of amorphous carbon (a―C) films having embedded nanocrystallites deposited by filtered cathodic jet carbon arc technique has been investigated. X-ray diffraction exhibits predominantly an amorphous nature of the film. High resolution transmission electron microscope investigations reveal largely an amorphous structure. However, an ultra-fine nanograined microstructure with the average grain size between 20 and 50 nm was observed throughout the entire film and the majority of the individual grains were single crystallites with the preferred interplanar spacing of about 0.2 nm. All the parameters evaluated were seen to depend strongly on the negative substrate bias and exhibit maxima or minima in the properties of the films deposited at − 150 V substrate bias. These a-C films having embedded nanocrystallites act as hard coating materials.