Electron cyclotron resonance deposition, structure, and properties of oxygen incorporated hydrogenated diamondlike amorphous carbon films J. Appl. Phys. 96, 5456 (2004); 10.1063/1.1804624Effects of thermal annealing on the structural, mechanical, and tribological properties of hard fluorinated carbon films deposited by plasma enhanced chemical vapor depositionThe effect of annealing in an ultrahigh vacuum on the chemical structure of diamondlike carbon ͑DLC͒ was investigated using photoelectron spectroscopy, thermal desorption spectroscopy, electrical resistivity, and micro-Raman spectroscopy measurements. The line shapes of the C 1s photoelectron spectra depended on annealing temperature. The relative intensities of four chemical components in the spectra were quantitatively evaluated: sp 3 carbon with carbon-carbon bonds ͑C-C sp 3 carbon͒, sp 2 carbon with carbon-carbon bonds ͑C-C sp 2 carbon͒, sp 2 carbon with hydrogen-carbon bonds ͑H-C sp 2 carbon͒, and sp 3 carbon with hydrogen-carbon bonds ͑H-C sp 3 carbon͒. The variation of the ratio of the components demonstrated that hydrogen in DLC is emitted to the outside in between 450 and 600°C, and the remaining DLC is graphized above 600°C. The increase in the asymmetry of the C 1s spectra and the decrease in the electrical resistivity of the DLC film with annealing temperature agree with the picture that the H-C bonds in DLC produces large free spaces in the structure, which inhibit conductive routes and lead to high electrical resistivity.
Angle-resolved x-ray photoelectron spectroscopy was used to investigate the surface of a diamondlike carbon film prepared by the ionized deposition method. We then analyzed the C 1s spectra using the Doniach-Šunjić (DŠ) [J. Phys. C 3, 285 (1970)] function convoluted with a Gaussian function. Consequently, we obtained four fitting curves for the carbon components in each spectrum, regardless of the assumption of the singularity index (α) in the DŠ function, which expresses the asymmetry of the C 1s spectrum. The curves were assigned in the order of binding energy to bulk sp3 carbon (283.7–283.8eV), bulk sp2 carbon (284.2–284.3eV), surface sp2 carbon (284.7–284.8eV), and surface sp3 (285.3–285.4eV) carbon. We further considered the influence of the assumption of α. Consequently, we suggest that the C 1s spectra can be quantitatively analyzed without considering the influences of α when the ratio of α for sp2 carbon to that for sp3 carbon [α(sp2):α(sp3)] is between 10:0 and 5:5. The distribution in the α ratio may indicate that the sp2 and the sp3 carbon atoms can interact with each other (hybridization) and differ from those highly oriented pyrolytic graphite and diamond, respectively.
The surface structures, photovoltages, and stability of n-Si(111) electrodes surface-modified with Pt nanodots and organic groups were studied in an I-/I3- redox electrolyte, using alkyls of varied chain length and those having a double bond and ester at the terminal as the organic groups. The n-Si was first modified with the organic groups, and then Pt was electrodeposited on it. Linear sweep voltammetry revealed that, for the modification with alkyls, the overvoltage for the Pt deposition became significantly larger with increasing alkyl chain length, though this does not necessarily hold for the modification with alkyls having a double bond and ester. Scanning electron microscopic inspection showed that the Pt particle density decreased and the particle size increased, with increasing alkyl chain length. The photovoltaic characteristics and stability for the n-Si electrodes modified with the organic groups were much improved by the Pt nanodot coating, though they became somewhat inferior with increasing alkyl chain length. On the basis of these results, it is concluded that surface alkylation at high coverage together with coating with small Pt nanodots gives efficient and stable n-Si electrodes.
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