X. Shi

School of EEE, Nanyang Technological University, Singapore 639798
esxu@ntu.edu.sg

Filtered Cathodic Vacuum Arc (FCVA) is a new coating technology that has been receiving growing attention in some important application areas including hard disk media and slider coatings. The FCVA technology developed in Nanyang Technological University, Singapore has the capability of producing large area uniform and clean tetrahedral amorphous carbon (ta-C) coatings at a desired rate. Design related modeling work will be discussed.

Mechanical properties of the (ta-C) films will be reviewed. Hardness, Young's modulus, frictional coefficient and critical load vary almost linearly with sp3 content in the film. It is indicated from the morphological and Raman results that the maximum achievable sp3 content in ta-C films is about 90%. The variation of the band tail structure in ta-C films was studied using spectro-ellipsometry. The defect density in the band tail reaches a minimum value when the sp3 content is the highest. The defect density around the Fermi level was obtained from the low temperature conductivity measurement. Together with the spectro-ellipsometry measurement, it is seen that the nitrogen acts as a weak passivation material for the dangling bonds in the ta-C film. When the nitrogen level in the film varying from 0 to 5% and then to 34%, the film undergoes changes from as deposited weak p-type to intrinsic and then to heavily doped n-type, respectively.