Effect of target self-bias voltage on the mechanical properties of diamond-like carbon films deposited by RF magnetron sputtering

Abstract

Diamond-like carbon (DLC) thin films were deposited by RF magnetron sputtering under different target self-bias voltages from −290 to −1090 V. Mechanical properties of these films in terms of hardness, Young's modulus, elastic recovery, and plastic resistance parameter ( H/ E) under different target self-bias voltages were analysed by the nanoindentation technique. Hardness and Young's modulus were found to increase in the range of 11–22 and 110–152 GPa, respectively, with increase of target self-bias voltage. The Korsunsky composite hardness model was used in order to determine the true hardness of DLC films from measurement on the film/substrate system. Residual stress in the films, measured using the bending beam method, was found to be compressive and increased with the increase of target self-bias voltage. The variation of intensity ratio, I d/ I g and the position of G-band of the DLC films with respect to target self-bias voltage were also investigated by Raman spectroscopy.