Long-term irradiation effects of visible light on amorphous carbon nitride films

Abstract The effect of long-term visible-light irradiation on the photo-induced deformation of amorphous carbon nitride (a-CN x ) films was investigated. a-CN x films were deposited on SiO 2 substrates (30 × 2 × 0.05 mm 3 ) using reactive radio frequency magnetron sputtering. Deformation of the a-CN x films was measured using continuous wave (CW) or pulsed monochromatic light with a wavelength of 470 nm. Pulsed light irradiation was applied for a total of 60 min with an on/off pulse period of 60 s, while CW light irradiation was performed for 120, 190, and 759 min with different light intensities so that the total photon flux remained constant. In all cases, the extent of photo-induced deformation of the a-CN x films before and after irradiation did not change. The chemical bonding states determined from X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy analyses indicated no significant changes after illumination. In addition, electron spin resonance (ESR) spectroscopy measurements indicated that there was no increase in the defect density after illumination. The long-term stability of a-CN x films is one of the main advantages for their use in light-driven microactuator systems.