Photomechanical response of amorphous carbon nitride thin films on SiO2 substrate

Abstract

Photo-induced deformation of amorphous carbon nitride (a-CNx) thin films was observed under visible light irradiation. This phenomenon shows the energy conversion of photon energy to mechanical energy. The a-CNx films were prepared on rectangular ultrathin SiO2 substrates by reactive radio frequency magnetron sputtering method at different deposition temperatures. The graphite like films were obtained with increasing the deposition temperature. In order to evaluate the photomechanical response of a-CNx, the time resolved bending deformation of the a-CNx/SiO2 specimens was measured using optical-lever technique when the incident light was turned on and off. The absolute amount of bending deformation was found to be the maximum value with the specimen deposited at 573 K. As a result of the time resolved measurement of the photomechanical response of the a-CNx/SiO2 specimens, all of the specimens began to be bent immediately when the light was turned on and off, and then the deformation reached to the saturation value after about 4 s. The photomechanical response speed increased with increasing the nitrogen concentration, and the graphite like specimen showed low photomechanical responsivity.