Characterization of Diamond Films Grown on Amorphous SiO ₂

Continuous diamond film growth on SiO₂ was achieved by an effective pretreatment. Carbon implantation and diamond powder abrasion were used to enhance diamond nucleation on SiO₂. The possibility of using two gas mixtures (CH₄–CO₂ and CH₄–H₂) in order to achieve the growth of continuous diamond films on SiO₂ was examined. The diamond film growth rate obtained using the CH₄–CO₂ gas mixture was 0.6 µm/h which is roughly three times higher than that of the CH₄–H₂ gas mixture. CH₄–H₂ gas mixtures had a lower etching reaction rate than that of CH₄–CO₂ gas mixtures. The higher etching rate of the CH₄–CO₂ gas mixture was considered to be due to a higher concentration of active carbon radicals or carbon-containing species in the plasma. Scanning electron microscopy (SEM) and optical emission spectroscopy (OES) indicated that active carbon radicals and carbon-containing species are the major cause of pits arising at the surface. Using CH₄–H₂ gas mixtures at a low microwave power gave the optimum reaction conditions for depositing diamond films on SiO₂ layers.