The role of hydrogen in nitrogen-containing diamondlike films studied by photoelectron spectroscopy

The influence of H on the local structure of N-containing amorphous diamondlike films (a-CNx:H) is reported. The samples were prepared by rf sputtering of graphite in a N-2, Ar, and H-2 atmosphere. The chemical bonding of C and N atoms was inferred by analyzing the C 1s and N 1s electronic core-level by x-ray photoelectron spectroscopy. Hydrogen free films present N Is peaks with a ''doublet'', located at 398.2-400.5 eV. When II is introduced in the preparation chamber, the doublet evolves to a single wider band located at 399.1 eV. This new band becomes dominant when increasing H-2 partial pressure, completely hiding the original structure. High H-2 partial pressure interrupts the growing network formed by N and C due to the attachment of H to N and/or C. Furthermore, the experimental results suggest that the possibility of formation of the C3N4 phaselike is inhibited by the presence of hydrogen. (C) 1997 American Institute of Physics.