Influence of applied bias voltage on the composition, structure, and properties of Ti:Si-codoped a-C:H films prepared by magnetron sputtering

Abstract

The titanium- and silicon-codoped a-C:H films were prepared at different applied bias voltage by magnetron sputtering TiSi target in argon and methane mixture atmosphere. The influence of the applied bias voltage on the composition, surface morphology, structure, and mechanical properties of the films was investigated by XPS, AFM, Raman, FTIR spectroscopy, and nanoindenter. The tribological properties of the films were characterized on an UMT-2MT tribometer. The results demonstrated that the film became smoother and denser with increasing the applied bias voltage up to -200 V, whereas surface roughness increased due to the enhancement of ion bombardment as the applied bias voltage further increased. The sp3 carbon fraction in the films monotonously decreased with increasing the applied bias voltage. The film exhibited moderate hardness and the superior tribological properties at the applied bias voltage of -100 V. The tribological behaviors are correlated to the H/E or H 3/E2 ratio of the films. © 2014 Jinlong Jiang et al.