Sp3/sp2 character of the carbon and hydrogen configuration in micro- and nanocrystalline diamond

Hot filament and microwave plasma CVD micro- nanocrystalline diamond films are analysed by visible and ultra-violet excitation source Raman spectroscopy. The sample grain size varies from 20 nm to 2 mu m. The hydrogen concentration in samples is measured by SIMS and compared to the grain size, and to the ratio of sp(2) carbon bonds determined by Raman spectroscopy from the 1332 cm(-1) diamond peak and the sp(2) 1550 cm(-1) G band. Hydrogen concentration appears to be proportional to the sp(2) bonds ratio. The 3000 cm(-1) CH(x) stretching mode band intensity observed on the Raman spectra is decreasing with the G band intensity. Thermal annealing modifies the sp(2) phase structure and concentration, as hydirogen outdiffuses. (C) 2007 Elsevier B.V. All rights reserved.