Diamond-like carbon nanocrystals formed by implanting fused quartz and sapphire (α-Al2O3) with carbon ions

In an attempt to synthesize diamond nanocrystals 1 MeV carbon ions were implanted into fused quartz and sapphire to several different doses and annealed in a furnace at 1100°C for different durations in different annealing ambients. We observe a peak in the optical absorption spectrum at around 5 eV in carbon-implanted quartz and sapphire samples after thermal annealing. We studied the behaviour of the absorption peak as a function of carbon ion dose, annealing time and ambient. Raman spectroscopy using the 514.5 nm line of an argon ion laser was used to elucidate the nature of the chemical bonding in the carbon-implanted samples. Several sharp hitherto unknown Raman peaks are observed in carbon-implanted and annealed sapphire which are consistent with the presence of diamond-like carbon clusters.