Influence of Si–C bond density on the properties of a-Si1−xCx thin films

Amorphous silicon carbide (a-Si1−xCx) films were deposited on silicon (1 0 0) and quartz substrates by pulsed DC reactive magnetron sputtering of silicon in methane (CH4)–Argon (Ar) atmosphere. The influence of substrate temperature and target power on the composition, carbon bonding configuration, band gap, refractive index and hardness of a-SiC films has been investigated. Increase in substrate temperature results in slightly decreasing the carbon concentration in the films but favors silicon–carbon (Si–C) bonding. Also lower target powers were favorable towards Si–C bonding. X-ray photoelectron spectroscopy (XPS) results agree with the Fourier Transform Infrared (FTIR), UV–vis spectroscopy results. Increase in substrate temperature resulted in increased hardness of the thin films from 13 to 17 GPa and the corresponding bandgap varied from 2.1 to 1.8 eV.