Nano Ni Dot Effect on the Structure of Tetrahedral Amorphous Carbon Films

Nano-scale manipulation of thin film structure has attracted much attention, owing to their possibilities to obtain novel properties associated with the nano-scale microstructure. A great effort is also focusing on the nano-scale manipulation of tetrahedral amorphous carbon (ta-C) films. Multilayer structures composed of ta-C films of different properties are the most widely investigated structure. In the present work, we demonstrated that nano-sized graphitic columns embedded in hard amorphous ta-C matrix could be prepared by using nano-sized Ni dots on the substrate surface. The Ni dots were prepared by annealing Ni thin film of thickness ranging from 3 to 13 nm. The ta-C film was then deposited by filtered vacuum arc process. Microstructure analysis and electrical resistivity measurement showed that nano-scale columns of highly conducting graphitic phase grew at the Ni dots. Size of Ni dot has significant effects on the nano-scale structure evolution, and thus mechanical and electrical properties. The growth of the graphitic phase was discussed in terms of the catalyst effect of Ni for the transformation of carbon materials into stable graphitic phase.