Diamond-like carbon thin films prepared by pulsed-DC PE-CVD for biomedical applications

In the present research, diamond-like carbon (DLC) thin films were applied on steel substrates by means of pulsed-direct current (DC) plasma-enhanced chemical vapor deposition (PE-CVD). The effects of bias voltage and deposition pressure on the films' structure and properties were investigated. The Raman spectra of the films revealed features typical of G and D bands, indicating the formation of a DLC phase. The results demonstrate that the sp(3) carbon fraction or the so-called diamond-like character of the DLC films increased with increasing bias voltage. Moreover, an increase in the bias voltage resulted in a decrease in the film thickness from 800 to 200 nm. Also, the DLC films prepared at a higher deposition pressure showed a higher fraction of sp(2)-bonded carbon - that is, graphitic domains. Furthermore, it was found that the variation in the bias voltage and deposition pressure also affected the internal stress values of the DLC films in a way that they increased from 1 to 11GPa when the bias voltage was increased from 475 to 675 V. The effectiveness of DLC films formed on the steel substrates can pave the way for developing a new class of advanced materials to enhance the performance of stainless steel for biomedical applications.