Structural analysis of Si-containing diamond-like carbon

Abstract

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.% by adjusting the ratio of methane (CH 4) 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 13C 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 29Si 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.