Bonding in hard and elastic amorphous carbon nitride films investigated using 15N, 13C, and 1H NMR spectroscopy -: art. no. 195401

The nitrogen bonding in hard and elastic amorphous carbon nitride (a-CNx) films is examined with N-15, C-13, and H-1 nuclear magnetic resonance (NMR) spectroscopy. Films were deposited by dc magnetron sputtering, in a pure nitrogen discharge on Si(001) substrates at 300 degreesC. Nanoindentation tests revealed an elastic recovery of 80%, a hardness of 5 GPa, and an elastic modulus of 47 GPa. The NMR results show that nitrogen bonding in this material is consistent with sp(2) hybridized nitrogen incorporated in an aromatic carbon environment. The data also indicate that the a-CNx prepared for this study has very low hydrogen content and is hydrophilic. Specifically, analysis of N-15 and C-13 cross polarization magic angle spinning and H-1 NMR experiments suggests that water preferentially protonates nitrogen sites.