Optical properties of mixed phase a-C/diamond films deposited by dc magnetron sputtering of vitreous carbon target

Abstract

Mixed phase a-C/diamond films were deposited on glass and fused silica substrates by dc magnetron sputtering of a vitreous carbon target in argon plasma. The optical characterization of the films, deposited at zero bias voltage, ( V B = 0) indicated a high band gap ( E g > 3eV). E g increased further when deposited with negative bias voltage ( V B = − 100 V). The variations of stress (0.5–4 GPa) and strain (0.6 × 10 −3–8 × 10 −3) with deposition temperature (300 K ⩽ T s ⩽ 573 K) were determined by a non-destructive optical technique. The hardness ( H v) of the films deposited simultaneously (at T s ~ 573 K) on glass, fused silica and silicon substrates indicated a variation within 18–23 GPa. FTIR studies of the films deposited on Si indicated high sp 3 content (> 80%) with predominant CH stretching modes within 2800–3000 cm −1.