Effect of DC negative bias on structure and properties of nitrogen doped diamond-like carbon films synthesized by HWP-CVD technique

摘要

In this paper, nitrogen doped diamond-like carbon (N-DLC) films are successfully prepared by helicon wave plasma (HWP) on silicon substrates in Ar/CH4/N2 gas mixtures at different DC negative bias voltages (-VDC). The surface morphology, structure and properties of N-DLC films have been studied by SEM, AFM, Raman and XPS. The deposition rate of the film decreases with increasing -VDC from 0 V to -50 V. The results of Raman spectra show that ID/IG decreases from 1.22 to 1.10 with increasing -VDC. The elemental surface composition of the N-DLC films has been analyzed by XPS. The results show that the N content and sp3/sp2 ratio of the N-DLC films increase with the increase of -VDC. Young's modulus values measured by AFM in SPM mode also show the expected increase with increasing -VDC. Moreover, the N-DLC electrode has been used to study the electrochemical reversibility.