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.

Effect of Substrate Bias and Temperature Variation in the Capacitive Coupling of SOI UTBB MOSFETs

In this work, the electrical features related to the capacitive coupling and temperature influence of the Ultra-Thin Body and Buried Oxide SOI MOSFET (UTBB) transistors are explored through numerical simulations. The impact of the substrate bias is observed for a set of values ranging from -3 V to 2 V for a temperature range between 100 K and 400 K. Also, structures with different types of ground plane (GP-P and GPN) and without GPhave been evaluated. This approach analyzes the capacitive coupling through the body factor and shows that the negative biasing for all GP types significantly improves the structure coupling and that the device with P-type ground plane has the lowest value of body factor for all the evaluated conditions. The dependence of the body factor on the temperature has shown to be negligible for longer devices. However, for devices shorter than 50 nm, the position of the maximum electrons concentration inside the silicon layer may affect the capacitive coupling.

The Effects of Substrate Bias on the Properties of HfC Coatings Deposited by RF Magnetron Sputtering

In the paper, by using radio frequency (RF) magnetron sputter technology, the HfC coating grew on a 316L stainless steel substrate in an Ar atmosphere at various substrate bias voltages from 0 to −200 V. From the X-ray diffraction (XRD) and transmission electron microscopy (TEM) experiments, the HfC coatings were well crystallized and (111) preferential growth had been successfully obtained by controlling bias voltage at −200 V. Nanoindentation experimental results for the prepared HfC coatings indicated that they possessed the maximum nanohardness due to the formation of the (111) orientation. The results of electrochemical measurements displayed that 316L stainless steel (316L) coated with the HfC coatings had better corrosion resistance than bare 316L. With the bias voltage increasing to −200 V, adhesion of the 316L substrate with the HfC coating could be greatly improved, as well as corrosion resistance. The antithrombogenicity of the HfC coatings was identified by platelet adhesive and hemolytic ratio assay in vitro. It was shown that the hemocompatibility of coated 316L had been improved greatly compared with bare 316L and the HfC coatings possessed better antithrombogenicity with the bias voltage elevating above −150 V.