Deposition of amorphous CN_x by d.c. and rf plasma sputtering using a rf radical nitrogen beam source

Amorphous CN_x thin films were deposited by d.c. and rf Ar plasma sputtering combined with a nitrogen rf radical beam source which supplies active nitrogen species to the growing film surface. The dependence modifications of the optical and the structural properties on nitrogen incorporation were investigated using ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, a four-point-probe method and electron energy-loss spectroscopy. For the rf-sputtered films, the optical band gap was found to increase with the increase in the nitrogen content. For the d.c.-sputtered films, the optical gap first decreased to zero at low nitrogen content, and then increased with a further increase in the nitrogen content. C-K energy-loss near-edge structure (ELNES) showed a slight broadening on the lower energy side. The local environment of C and N atoms are almost similar as observed by comparing the C-K and N-K ELNESs.