Analysis of chemical vapour deposited diamond films by X-ray photoelectron spectroscopy

Abstract

X-ray photoelectron spectroscopy (XPS) for elemental and phase analysis of diamond surfaces is reviewed, including both single crystal natural diamond and polycrystalline chemical vapour deposition (CVD) films. The core C1s peaks, plasmon losses and valence band spectra of sp 2 graphite are compared with those of sp 3 diamond, and briefly with mixed sp 2/sp 3 hard carbon films. Surface reconstructions are reviewed for diamond in the presence of hydrogen or following thermal annealing. Attention is drawn to the destructive effects of argon ion bombardment ‘cleaning’. The synthesis of CVD diamond, including the initial nucleation process, is described and the significance of hydrogen is explained. Chemical modification of the surface of diamond films is discussed, with relevance to sensors and field electron emission. XPS analysis of (111) polycrystalline films treated by atom beams of N, O, H, Cl is described and the influence of unwanted oxygen is emphasised. For both atom beam and furnace oxidation, the oxygen is incorporated into the (111) diamond surface as bridging C–O–C.