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When propane/nitrogen (C3H8/N2) mixtures are used to deposit carbon films by thermal chemical vapor deposition (CVD), effects of C3H8/(C3H8+N2) ratios on the deposition rate and microstructures of carbon films are investigated. Experimental results show that as the C3H8/(C3H8+N2) ratio increases from 20 to 100%, the deposition rate increases from 23.7 to 127 nm/min. Alternatively, if the residence time, deposition temperature, and working pressure raise, the deposition rate of carbon films also increases. The kinetics of this thermal CVD process is discussed. The activation energy obtained in this work is 234 kJ/mole. Furthermore, this CVD reaction is controlled by a process of about first order, which is resulted from the adsorption of main product gases, acetylene (C2H2) and ethylene (C2H4), on the silica glass plate substrate. Few nitrogen and hydrogen atoms are incorporated into carbon films. The crystallinity, ordering degree, and nano-crystallite size of carbon films decrease with increasing the C3H8/(C3H8+N2) ratio. Meanwhile, as the C3H8/(C3H8+N2) ratio increases from 20 to 100%, the sp2/(sp2+sp3) ratio of carbon films decreases from 92 to 61%. Finally, the results of thermal CVD carbon deposition using C3H8/N2 mixtures are compared with those using methane/nitrogen (CH4/N2), C2H2/N2, and C2H4/N2 mixtures

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This study investigates the effect of ammonia/methane (NH3/CH4) mixtures on characteristics of nitrogen-doped amorphous hydrogenated carbon (a-C:H(N)) films prepared by plasma enhanced chemical vapor deposition. The a-C:H(N) films with identical thickness are deposited on p-type silicon (p-Si) substrates using different NH3/CH4 ratios. These a-C:H(N)/p-Si junctions are a potential candidate to use in electronic or photoelectronic devices. The microstructures, optical properties, and mechanical properties of a-C:H(N) films are evaluated. Furthermore, the residual stresses in a-C:H(N) films, and also, the current density-voltage and capacitance density-voltage behaviors of a-C:H(N)/p-Si devices are investigated. Experimental results indicate that as the NH3/CH4 ratio increases from 0 to 0.2, the nitrogen/carbon ratio increases from 0 to 5.4%. The nitrogen-carbon bonds, nitrogen-hydrogen bonds, and sp(2) carbon fraction of carbon films enlarge with increasing NH3/CH4 ratio, while the deposition rate, ordered degree, optical band gap, reduced Young's modulus, hardness, and residual stress of carbon films decrease. The a:C:H(N)/p-Si device has an optimum electrical property at the NH3/CH4 ratio of 0.15 (or at the N/C ratio of 4.7%). Finally, the results of this study are compared with those reported in literatures. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.051202jes] All rights reserved