Study of oxygen on the three low index diamond surfaces by XPS

Nominally clean diamond surfaces have been shown to contain adsorbed foreign atoms on them. Some of the adsorbed atoms have also been known to lead to various surface modifications, a phenomenon that is important in diamond electronics. Establishing the identity and nature of the adsorbed atoms on these surfaces is therefore key to the successful application of diamond in various technological fields. In this work, X-ray photoelectron spectrometry (XPS) has been used to investigate the three low index diamond surfaces. The results show oxygen as the main foreign atom on these surfaces other than hydrogen, with varying fractions of oxygen monolayer coverage being observed. It is further established that the adsorbed oxygen exists in several bonding configurations, with the energy shifts associated with the various functional groups being determined.