Nitrogen Terminated Polycrystalline Diamond Surfaces by Microwave Chemical Vapor Deposition: Thermal Stability, Chemical States and Electronic Structure

In this work, we investigate the interaction of microwave (MW) N2 plasma with polycrystalline diamond surfaces. Optical emission spectroscopy (OES) was used to identify different species present in the plasma. The chemical states were investigated by X-ray photoelectron spectroscopy (XPS) and high resolution electron energy loss spectroscopy (HREELS), and the electronic structure was investigated by ultra violet photoelectron spectroscopy (UPS). OES showed that the MW(N2) plasma contains mainly radical species. The nitrogen coverage is estimated to be lower than the diamond average areal density. XPS analysis showed that the nitrogen may have occupied a number of bonding configurations. Upon annealing to 800 °C, some of the incorporated nitrogen onto the diamond was stable. From HREELS study, the N-H surface bond was still stable upon annealing to ~ 600 °C. The hydrogen terminated diamond exhibits negative electron affinity. Furthermore, there was another increase in the electron affinity upon the nitrida...