Morphological and phase evolution of nano-crystalline carbon films with a predominant diamond character

Abstract

Abstract In the present work, the evolution of nano-diamond films deposited by the glow discharge chemical vapour deposition method onto silicon substrates as a function of time were studied by various complementary techniques. Our analysis showed that prior to formation and growth of continuous films of a predominantly nano-diamond character, a graphitic phase is formed. This graphitic film displays a preferred alignrnent of its basal planes perpendicular to the silicon substrate interface. The nano-diamond character of the films gradually evolves reaching a maximum value of ∼80% for film thickness larger than ∼0.5 μm. It was found that the appearance of the nano-diamond phase is initially accompanied with an increase in surface roughness which decreases with film growth. It was determined that the continuous nano-diamond films are composed of diamond nano-crystallites, ∼5 nm in diameter alongside a sp2 bonded amorphous carbon phase. Most likely the amorphous carbon component in the films exists at the nano-diamond grain boundaries. The phase and morphological evolution of the films were investigated, with nanoscopic resolution, by a number of complementary spectroscopy and microscopy techniques: near edge X-ray adsorption fine structure, scanning electron microscopy and atomic force microscopy, high-resolution transmission electron microscopy and X-ray diffraction.