Preparation of boron-doped diamond-like carbon films via enhanced-PECVD using an additional cathode

Boron-doped Diamond-Like Carbon (B:DLC) films with different concentrations of boron were produced in an Enhanced-PECVD reactor using trimethylborate (TMB) vapor as the boron source. An additional cathode system was incorporated inside the reactor to confine the plasma to grow B:DLC film on polished Ti-6Al-4 V and Silicon samples. The boron-containing coatings were evaluated and compared to a boron-free coating through several characterization techniques. Raman spectroscopy, Nano-hardness, XPS, RBS, and SEM techniques were employed to study the microstructure, hardness, chemical composition and bonding state, and morphology of the samples. Ball-on-disc tests were also conducted, using a tribometer to measure the friction coefficient and wear resistance. Boron was confirmed in the DLC film structure by XPS and RBS analyses. The XPS measurements showed that the boron bonding was accompanied by a higher content oxygen than carbon content, which increased with the TMB concentration. The sp(3) content was evaluated, and the result showed a decrease of about 30 % with the higher solution concentration. As a consequence, the friction coefficient, wear, and hardness were affected. However, the adherence of the films was not compromised. Finally, our study indicated that the PECVD deposition system employing an additional cathode was suitable for the incorporation of boron into DLC films.