Characterization and mechanical properties of ion-implanted diamond surfaces

Single crystal diamond surfaces were treated by implantation of high energy nitrogen, chromium, and titanium ions. Ion energies were chosen between 60 and 180 keV and ion doses up to 1×1017 ions/cm2. The samples were heated to temperatures of approximately 750°C during implantation to prevent amorphization of the diamond crystal. The near-surface zone was characterized by X-ray photoelectron spectroscopy. To reduce the amount of lattice damage, some of the samples were coated with a sacrificial layer, e.g. 50 nm titanium, which was removed after ion implantation by dissolution in nitric acid. Mechanical properties of the implanted surfaces were tested under atmosphere by abrading with a bronze wheel wetted with diamond suspension. Reactive properties were examined in an ultra-high vacuum by grinding with an iron wheel. It is shown that the wear of the zone influenced by chromium implantation can be reduced significantly. This is explained by the presence of carbidic bonding combined with low damage of the diamond lattice.