Structural analysis of Si-containing diamond-like carbon

摘要

We have investigated the structures of silicon-containing diamond-like carbon (DLC-Si) films with various silicon contents. The DLC-Si films were deposited on steel substrates at 773 K by direct current plasma-enhanced chemical vapour deposition (DC-PECVD). The Si content in the films was controlled in the range of 4-28 at. percent by adjusting the ratio of methane (CH4) and tetramethylsilane (Si(CH_3)_4) as the precursor gases. Several typical spectroscopic measurements provided the film information; elastic recoil detection analysis (ERDA), hydrogen content; electron probe microanalysis (EPMA), carbon and silicon content; Fourier transform infrared (FT-IR), chemical bonding; and Raman scattering, networking due to the sp~2 carbon (Csp~2). In addition, solid-state ~(13)C nuclear magnetic resonance (NMR) measurements were able to quantify the two types of hybridized carbon atoms, Csp~2 and Csp~3. The cross-polarization technique provided more precise environments for the carbon atoms bonded to hydrogen atoms, suggesting that the environment of Csp~2 is quite different depending on the silicon content. The Si NMR measurement was also carried out to provide the circumstance of the four-coordinate Si atoms. In addition, the mechanical property of the films (hardness) was evaluated by the nanoindentation method in order to compare it with the film structure.