Effects of hydrogen incorporation on structural relaxation and vibrational properties of a-CN:H thin films grown by reactive sputtering

Proper hydrogen addition in sputtered carbon nitrides is shown to remarkably reduce the film internal constraints. Significant differences in the hydrogen bonding are evidenced by infrared (IR) spectroscopy. Thus, the small variation (from 14 to 20%) of the total film H-content is accompanied by relevant changes in the microstructures of a-CN:H films. The results of the IR characterisation and Raman analysis of the 1000-1700 cm-1 (D- and G-modes) region are comparatively discussed in the light of the currently-utilised model, as well as of the recently-emerging interpretations contemplating vibrations of odd-fold rings.