Contribution of nitrogen to the photoinduced deformation of amorphous carbon nitride films

Amorphous carbon nitride (a-CNx) films show photoinduced deformation under visible light illumination. To investigate the effect of nitrogen on this deformation, we compared the deformation of a-CNx films with that of nitrogen-free amorphous carbon films. The films were deposited on a rectangular ultrathin Si substrate to obtain the amount of deformation estimated from the bending curvature of the substrate. The amount of photoinduced deformation was increased by nitrogen incorporation. In the case of a nitrogen concentration (N/C) of 0.3, the deformation was under the detection limit of our apparatus. By detailed analysis of chemical bonding states, the amount of deformation was found to increase with increasing N/C ratio and N-sp(3)C/N-sp(2)C ratio, which increased with increasing nitrogen content. Furthermore, from the results of Fourier transform infrared spectroscopy, it is found that the photoinduced deformation occurred through the formation of triple bonds as the termination structures related to nitrogen and chain bonds. (C) 2016 The Japan Society of Applied Physics