Diamond-like carbon films(DLC) were deposited on single crystalline silicon surface under different pulsed negative biases in an ECR(electron cyclotron resonance) plasma source.Chemical structure and morphology were characterized by Fourier transformation infrared spectroscopy(FT-IR) and atomic force microscopy(AFM).Friction coefficient of the films was tested.The results show that the films

with smooth and dense morphology

were typical hydrogenated DLC with –CHn stretching in 2800-3000 cm-1.By increasing the pulsed negative bias

the FT-IR peak intensity of C-H stretching vibration increased with the pulsed negative bias

reaching a maximum at 200 V

and then decreased.And friction coefficient of the films decreased with the pulsed negative bias

reaching a minimum at 200 V

and then increased.