The effect of nitrogen on pulsed laser deposition of amorphous silicon carbide films: Properties and structure

The influence of nitrogen on amorphous silicon carbide films deposited at room temperature using pulsed laser ablation has been investigated. Depositions were carried out either in ultrahigh vacuum or in a nitrogen ambient ranging from 10 to 100 mT. The mechanical and optical properties, as well as composition and structure of the resulting films, were evaluated using a variety of analytical techniques. Vacuum-deposited films exhibited high hardness but suffered from high compressive stresses (>1 GPa). At low nitrogen background pressures (<30 mT), films with an optimum balance among hardness (∼16 GPa), adhesion, and intrinsic stress (<220 MPa) were found, making them ideal candidates for protective coating applications. As nitrogen pressure was increased, mechanical performance degraded due to the increasing amount of SiO₂ found in the films as evidenced by spectroscopic ellipsometry, infrared spectroscopy, and Auger electron spectroscopy measurements. The source of oxygen is attributed to residual water vapor present in our vacuum system. Optical emission spectroscopy was used to confirm the presence of Si-O species in the laser-induced plasma plume.