Microstructure and phase composition evolution of nano-crystalline carbon films: Dependence on deposition temperature

Nano-crystalline carbon films possessing a prevailing diamond or a graphite character, depending solely on substrate temperature and deposition time, can be deposited from a methane–hydrogen mixture by the direct current glow discharge plasma chemical vapor deposition method. In this study we investigate the evolution of nano-crystalline carbon films deposited in the 800–950 °C temperature range onto silicon substrates aiming to enlight the physicochemical processes leading to the formation of nano-diamond films. While at a deposition temperature of ∼880 °C the formation of a thin precursor graphitic film is followed by deposition of a film of diamond character, at higher and lower temperatures the films maintain their graphitic character. The morphology of the films and their growth rate vary with deposition temperature: slower growth rates and higher film roughness are obtained at lower temperatures suggesting the importance of kinetic effects during the growth process. For deposition times longer than ...