Structural and epsilon-near-zero characteristics of titanium carbide films with different carbon content

The face-centered cubic (Fcc) structured TiC_x films with different C content were prepared by reactive magnetron sputtering deposition. The influence of carbon content on the TiC_x crystal structure and dielectric properties were studied. All the films are fcc structured with (111) and (200) preferential orientation. Additionally, a tunable dual epsilon-near-zero characteristic is exhibited in visible and near infrared region. With C content increasing, the screened plasma frequency decreases. The calculated electronic states shows that atom vacancy is the main defect type underlying the optical response, while Ti antisites, Ti interstitials, Ti dumbbells or Ti interstitials may be the main factors influencing the crystal structure.