Incorporation of nitrogen into polycrystalline diamond surfaces by RF plasma nitridation process at different temperatures: Bonding configuration and thermal stabilty studies by in situ XPS and HREELS

摘要

In situ studies of low energy nitrogen species incorporated into diamond films are significant as they could lead to a better understanding of bonding configuration and defects formation of the modified surface. In this report, we investigate the interaction of radio frequency (RF) nitrogen plasma onto a polycrystalline diamond surface at different temperatures (RT, 250, 500, and 750 ℃). The influence of RF nitridation temperature on the bonding configuration, thermal stability, and concentrations of incorporated species were systematically investigated by in situ X-ray photoelectron spectroscopy and high resolution electron energy loss spectroscopy (HREELS). Our results showed that local bonding configurations were influenced by the temperature of the RF nitridation process. The amount of nitrogen incorporated into the diamond surface decreased as the nitridation process temperature increases. RF nitridation performed at 750 ℃ showed the absence of reorganization in the local bonding configurations upon annealing to 1000 ℃ and their thermal stability was also found to be better. HREELS results displayed partial retrieval of the characteristic optical phonon overtone of diamond, after annealing to 500 ℃, which indicates that the RF nitridation process was successful in incorporating nitrogen into diamond surface without inducing a graphitic near surface region.