Surface oxygenation studies on ( 1 0 0 )-oriented diamond using an atom beam source and local anodic oxidation
Surface oxidation studies on pre-deuterated (1 0 0)-oriented single crystal diamond have been performed by oxidizing the diamond surfaces macroscopically using an oxygen atomic beam source as well as microscopically using local anodic oxidation by atomic force microscope (AFM). Oxygen-deuterium exchange on diamond (1 0 0) was investigated by X-ray photoelectron spectroscopy, elastic recoil detection and time-of-flight SIMS. Exchange of pre-adsorbed D by atomic O is thermally activated, with almost complete exchange of surface D by atomic O at 300 °C. At higher oxidation temperatures, oxidation states which are chemically shifted from the C 1s bulk peak by 3.2 eV was observed together with a disordering of the diamond surface. Micron-scale, localized oxygenation of the diamond surface at room temperature could be achieved with a biased AFM tip where we confirmed that the modified areas show a lower secondary electron yield and higher oxygen content. In addition, the electronic structure of the oxygenated diamond surface (on-top (OT) and bridging model) has been investigated by calculating the layered-resolved partial density of states using first principles plane wave ab initio pseudopotential method within the local density functional theory. For the oxygen OT model, sharp features due to occupied surface states in the valence band and unoccupied surface states in the gap exist. The increase in emission intensity near the valence band edge for oxygenated diamond (1 0 0) was verified by ultraviolet photoelectron spectroscopy study.