| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 98 === This study investigates the effects of different radio-frequency (rf) powers on the properties of carbon coatings on optical fibers that are prepared by thermal chemical vapor deposition enhanced with inductively coupled plasma. Methane (16 sccm) and nitrogen (4 sccm) were used as the precursor gases, and rf powers were set between 0 and 400 W. The deposition temperature, working pressure, and deposition time were set to 975 ℃, 4 kPa, and 2 hours, respectively. The coating thickness, microstructure, surface roughness, surface property, electrical property, and low-temperature morphology of carbon coatings were investigated by field emission scanning electron microscopy, X-ray diffraction spectrometer, Raman scattering spectrometer, X-ray photoelectron spectrometer, atomic force microscopy, contact angle meter, four-points probe, and optical microscopy. The results indicate that the deposition rate increases as the rf power increases from 0 to 200 W, but the deposition rate decreases as the rf power exceeds 200 W. The mean crystallite size (Lc) increases with increasing the coating thickness, but the degree of ordering and in-plane crystallite size (La) decrease. Moreover, when the rf power increases, the carbon coatings have more sp2 carbon atoms and become graphite-like. The results also show that the surface roughness is inversely related to the water contact angle. As the rf power increases from 0 to 400 W, the electrical resistivity of carbon coatings decreases from 56.96 to 14.01 Ω‧μm. Finally, based on the low-temperature morphologies of carbon coatings, as the coating thickness exceeds 76 nm, the carbon coating has the ability to withstand thermal stress, and is good for use as a hermetical optical fiber coating.
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