Periodic density-functional study on oxidation of diamond (100) surfaces

The chemical reactions of the diamond surfaces with oxygen play important r oles in the chemical-vapor deposition process, etching, and wear of the sur face. In the present study, periodic density-functional calculations have b een performed to clarify the oxidation mechanisms of the hydrogenated diamo nd (100) surfaces. The oxidation processes have been simulated in terms of the reaction heats. The ether, hydroxyl, and ketone structures are found to be stable on the diamond (100) surfaces. At the initial stage of the oxida tion, the ether structures are priory formed at monohydride dimer bonds on the diamond (100) surfaces. The insertions of oxygen atoms into the lower l ayers are difficult to occur. As the coverage of oxygen atoms on the diamon d surface is increased, the formation of ketone structures becomes easier. The stable structure of the oxygen monolayer sensitively depends on the lat tice parameters. As the cell parameters are decreased, the bridge ether bec omes more stable and the on-top ketone becomes more unstable.