Effects of Substrate Bias Voltage on Structure of Diamond-Like Carbon Films on AISI 316L Stainless Steel: A Molecular Dynamics Simulation Study

With the recent significant advances in micro- and nanoscale fabrication techniques, deposition of diamond-like carbon films on stainless steel substrates has been experimentally achieved. However, the underlying mechanism for the formation of film microstructures has remained elusive. In this study, the growth processes of diamond-like carbon films on AISI 316L substrate are studied via the molecular dynamics method. Effects of substrate bias voltage on the structure properties and sp³ hybridization ratio are investigated. A diamond-like carbon film with a compact structure and smooth surface is obtained at 120 V bias voltage. Looser structures with high surface roughness are observed in films deposited under bias voltages of 0 V or 300 V. In addition, sp³ fraction increases with increasing substrate bias voltage from 0 V to 120 V, while an opposite trend is obtained when the bias voltage is further increased from 120 V to 300 V. The highest magnitude of sp³ fraction was about 48.5% at 120 V bias voltage. The dependence of sp³ fraction in carbon films on the substrate bias voltage achieves a high consistency within the experiment results. The mechanism for the dependence of diamond-like carbon structures on the substrate bias voltage is discussed as well.