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Nanostructured hydrogenated carbon nitride (CNx:H) thin films were synthesized on a crystal silicon substrate at low deposition temperature by radio-frequency plasma-enhanced chemical vapor deposition (PECVD). Methane and nitrogen were the precursor gases used in this deposition process. The effects of N2 to the total gas flow rate ratio on the formation of CNx:H nanostructures were investigated. Field-emission scanning electron microscopy (FESEM), Auger electron spectroscopy (AES), Raman scattering, and Fourier transform of infrared spectroscopies (FTIR) were used to characterize the films. The atomic nitrogen to carbon ratio and sp2 bonds in the film structure showed a strong influence on its growth rate, and its overall structure is strongly influenced by even small changes in the N2:(N2 + CH4) ratio. The formation of fibrous CNx:H nanorod structures occurs at ratios of 0.7 and 0.75, which also shows improved surface hydrophobic characteristic. Analysis showed that significant presence of isonitrile bonds in a more ordered film structure were important criteria contributing to the formation of vertically-aligned nanorods. The hydrophobicity of the CNx:H surface improved with the enhancement in the vertical alignment and uniformity in the distribution of the fibrous nanorod structures.

Amorphous carbon nitride (a-CNx) thin films were deposited using radio frequency plasma enhanced chemical vapor deposition (rf-PECVD) technique. A set of a-CNxthin films were prepared using pure methane (CH4) gas diluted with nitrogen (N2) gas. The rf power was varied at 50, 60, 70, 80, 90 and 100 W. The characterization techniques used were Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscope (FESEM). Humidity sensing properties of the a-CNxthin films were investigated by recording their electrical response to relative humidity (RH) at room temperature. Chemical bonding analysis clearly showed the presence of nitrile bands in the deposited films. The FESEM images of the films show a porous, granule-like and dendritic morphology. The average resistance of the a-CNxthin film is changed from 23.7 kΩ to 5.8 kΩ in the range of 5 to 95%RH. The films show a good response and repeatability as a humidity sensing materials. This work showed that rf power has a significant effects on the chemical bonding, morphology and electrical properties of the a-CNxfilms.

Structural and electronic properties of electron cyclotron resonance plasma deposited hydrogenated amorphous carbon and carbon nitride films Journal of Applied Physics 91, 4154 (2002) Abstract. Amorphous carbon nitride (a-CN x ) thin films were deposited using radio frequency plasma enhanced chemical vapor deposition (rf-PECVD) technique. A set of a-CN x thin films were prepared using pure methane (CH 4 ) gas diluted with nitrogen (N 2 ) gas. The rf power was varied at 50, 60, 70, 80, 90 and 100 W. These films were then annealed at 400 o C in a quartz tube furnace in argon (Ar) gas. The effects of rf power and thermal annealing on the chemical bonding and morphology of these samples were studied. Surface profilometer was used to measure film thickness. Fourier transform infra-red spectroscopy (FTIR) and Field emission scanning electron microscopy (FESEM) measurements were used to determine their chemical bonding and morphology respectively. The deposition rate of the films increased constantly with increasing rf power up to 80W, before decreasing with further increase in rf power. Fourier transform infra-red spectroscopy (FTIR) studies showed a systematic change in the spectra and revealed three main peaks included C-N, C=N, C=C and C≡N triple bond. C=N and C≡N bonds decreased with increased C-N bonds after thermal annealing process. The FESEM images showed that the structure is porous for as-deposited and covered by granule-like grain structure after thermal annealing process was done. The resistance of the a-CN x thin film changed from 23.765 kΩ to 5.845 kΩ in the relative humidity range of 5 to 92 % and the film shows a good response and repeatability as a humidity sensing materials. This work showed that rf power and thermal annealing has significant effects on the chemical bonding and surface morphology of the a-CN x films and but yield films which are potential candidate as humidity sensor device.

The present work highlights the facile synthesis of hydrophobic palm fatty acid functionalized Fe3O4 nanoparticles (MNP-FA) for the efficient removal of oils from the surface of water. An intense hydrophobic layer was introduced on the surface of Fe3O4 nanoparticles functionalized by the palm fatty acid obtained from the hydrolysis of palm olein. Scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Energy dispersive X-ray spectroscopy (EDX) and water contact angle analysis (WCA) measurements were used to characterize the newly fabricated palm fatty acid adorned magnetic Fe3O4 nanoparticles (MNP-FA). The obtained results confirmed the successful synthesis of palm fatty acid-functionalized magnetic nanoparticles. Oil removal tests performed with MNP-FA revealed that this newly prepared material could selectively adsorb lubricating oil up to 3.5 times of the particles' weight while completely repelling water. The main parameters affecting the adsorption of oil i.e., sorption time, mass of sorbent and pH of water were optimized.

Amorphous carbon nitride (a-CN x) thin films were deposited by radio frequency plasma enhanced chemical vapor deposition (rf-PECVD) technique. A set of a-CN x thin films were prepared using pure methane (CH 4) gas diluted with nitrogen (N 2) gas. The N 2 to CH 4 flow rate ratios calculated as N 2 /(N 2 +CH 4) were varied at 20, 30, 50, 60 and 70 %. These samples were then annealed at 400 o C in a quartz tube furnace in argon (Ar) gas. The effects of N 2 dilution and thermal annealing on the structural and optical properties of these samples were studied. A surface profilometer was used to measure film thickness. A field emission scanning electron microscopy (FESEM) and a ultraviolet-visible spectrophotometer (UV-Vis) measurements were used to determine their structural and optical properties, respectively. The thickness of the as-deposited films decreased with increased N 2 composition ratio. However, the thickness increased when these films were annealed. The FESEM images showed that the grain size of as-deposited and annealed films increased with the increased of N 2 composition ratios. But the the grain size decreased with a more orderly arrangement after the annealing process. The energy gap (E g) of the both set films increased with the increase in N 2 composition ratio up to 50% and significantly decreased with further increased in N 2 composition ratio. However, E g is decreased when the films were annealed. The variations in the thickness and optical properties of these CN x films when annealed relate to modifications in the film structure.

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