Photomechanical Response of Amorphous Carbon Nitride Thin Films on SiO&lt;sub&gt;2 &lt;/sub&gt;Substrate

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Amorphous carbon nitride (a-CN x ) deposited by reactive sputtering shows deformation, photoconductive behavior, and thermal radiation by visible light irradiation. In this study, we investigated these photoresponse behaviors of a-CN x . To obtain films with different bonding structures, the films were deposited at various temperatures from 473 to 873 K. A reduction in N/C ratio led to a decrease in C–N bonding fraction and an increase in graphite component. The optical band gaps decreased with increasing temperature. Under white light illumination, the surface temperature of a-CN x increased with the narrowing of the band gap owing to the conversion of photon energy primarily into thermal energy. On the photoconductivity and deformation, a nonlinear relationship to the band gap energy was observed. In addition, both these photoresponses showed opposite trends in relation to the deposition temperature. The photoinduced deformation was suppressed by increasing the graphite component and decreasing the C–N bonding fraction.

Section: Resultsmentioning

confidence: 99%

Response to visible light in amorphous carbon nitride films prepared by reactive sputtering

Aono¹,

Harata²,

Kitazawa³

et al. 2015

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“…On an a-CN x =SiO 2 bilayer specimen with dimensions of 2 × 30 × 0.05 mm 3 , the amount of photoinduced deformation is less than 400 µm and the response takes a few seconds to complete. 11) To increase the amount of photoinduced deformation, we prepared self-standing films and films deposited on flexible substrates. Substrate materials should be not only flexible but also lightweight and have thermal stability, resistance to plasma radiation, and high-vacuum tolerance.…”

Section: Introductionmentioning

confidence: 99%

Deposition of amorphous carbon nitride films on flexible substrates by reactive sputtering for applications in light-driven active devices

Aono

Harata

Odawara

et al. 2017

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Amorphous carbon nitride (a-CNx) thin films deposited by reactive sputtering have great potential for driving source applications of light-driven active devices. We demonstrate, for the first time, the photoinduced deformation of a-CNx deposited on flexible substrates, namely, poly(ethylene naphthalate) (PEN) films and transparent cellulose nanopaper. a-CNx films without delamination were obtained on both substrates. By decreasing the thickness of PEN films, the photoinduced deformation became extremely large. A light-driven pump was fabricated using a-CNx-coated PEN films, and then the pumping motion was observed up to 10 Hz. When a He-Ne laser traced the surface of a-CNx films deposited on the nanopaper, the sample moved to the opposite side of the laser spot. The motion involved repeated expansions and contractions similar to the motion of caterpillars occurring owing to the temporary photoinduced deformation of a-CNx films.

“…8) There are some important findings about the deformation of a-CN x films: (1) such deformation is mainly induced by photon energy directly, 9) (2) the response to the incident light with one arbitrary wavelength in the visible light is reversible by turning the light on and off, 10) (3) the deformation begins immediately after the light is turned on or off, and then it takes about 2-10 s to saturate. 11) Thus, we intend to apply the photoinduced deformation of a-CN x films to light-driven microactuators in the future. Presently, the driven systems of microactuators in micromachines generally utilize electrostatic force, 12) the piezoelectric effect, 13) or heat 14) among others.…”

Section: Introductionmentioning

confidence: 99%

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

Harata¹,

Aono²,

Kitazawa³

et al. 2015

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Amorphous carbon nitride (a-CN x ) films show photoinduced deformation under visible light illumination. To investigate the effect of nitrogen on this deformation, we compared the deformation of a-CN x 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–sp3C/N–sp2C 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.