Measurement and Simulation of Mechanical and Optical Properties of Sputtered Amorphous SiC Coatings

In this work we report on the extensive characterization of amorphous silicon carbide (a-SiC) coatings prepared by physical deposition methods. Our investigation is performed within the perspective application of a-SiC as an optical material for high-precision optical experiments and, in particular, in gravitational wave interferometry. We compare the results obtained with two different sputtering systems [a standard radio frequency (rf) magnetron sputtering and an ion-beam sputtering] to grasp the impact of two different setups on the repeatability of the results. After a thorough characterization of structural, morphological, and compositional characteristics of the prepared samples, we focus on a detailed study of the optical and mechanical losses in those materials. Mechanical losses are further investigated from a microscopic point of view by comparing our experimental results with molecular dynamic simulations of the amorphous SiC structure: first we define a protocol to generate a numerical model of the amorphous film, capturing the main features of the real system; then we simulate its dynamical behavior upon deformation in order to obtain its mechanical response.