Tetrahedral amorphous carbon

Rolo, M. C., Andujar, J. L., Robertson, J., and MUne, W. I., Preparation of Tetrahedral Amorphous Carbon Films by Filtered Cathodic Vacuum Arc Deposition," Diamond Relat. Mater., Vol. 9,2000, pp. 668-661. 

Hyodo, H., Yamamoto, T., and Toyoguchi, T., "Properties of Tetrahedral Amorphous Carbon Film by Filtered Cathodic Arc Deposition for Disk Overcoat, IEEE Trans. Magn., Vol. 37, 2001,pp. 1789-1791. 

Han, H., Ryan, R, and McClure, M., Ultra-thin Tetrahedral Amorphous Carbon Eilm as Solider Overcoat for High Areal Density Magnetic Recording," Surface and Coatings Technology,Vol. 121,1999,pp. 579-584. 

One more variety of amorphous carbon is the so-called tetrahedral amorphous carbon (ta-C). Unlike the above-discussed a-C H films, ta-C contains practically... 

Microstructural changes of amorphous cartwn (a-C) and tetrahedrally amorphous carbon (ta-C) upon laser irradiation is studied in this paper. As it is shown, ta-C films with higher ratio of sp bonded carbon atoms are more stable compare to low density a-C films. The sjf bonded atoms in a-C films start clustering at laser energies lower than the energy needed for clustering of sp bonded atoms in ta-C films. 

The broad band at 1110 cm (Fig. 42b) has also been repeatedly observed in the Raman spectra of indentations in diamond. It was initially assigned to amorphous diamond [4, 196]. However, both the experimental Raman spectra of sp -bonded amorphous films [203] and the calculated vibrational density of states of an amorphous carbon network constrained to be fully -bonded [204] show a strong peak at 1200 cm. In contrast, the vibrational density of states of tetrahedral amorphous carbon (ta-C) features a broad peak centered at 1100 cm [205], which is quite similar to that observed in Figure 42b. The ta-C networks should not be confused with amorphous diamond because they contain some portion of aromatically bonded sp carbon. 

GiUces KWR, Sands HS, Batchelder DN, Milne WI, Robertson J. Direct observation of sp(3) bonding in tetrahedral amorphous carbon UV Raman spectroscopy. J Non-Crystalline Solids 1998 227 612-6. 

Teo KBK, Rodil SE, Tsai JTH, Ferrari AC, Robertson J, Milne WI. Effect of graphitic inclnsions on the optical gap of tetrahedral amorphous carbon films. J Appl Phys 2001 89 3706-10. 

B.J. Chen, X.W. Sun, B.K. Tay, L. Ke and S.J. Chua, Improvement of efficiency and stability of polymer light-emitting devices by modifying indium tin oxide anode surface with ultrathin tetrahedral amorphous carbon film, Appl. Phys. Lett. 86, 063506/1-063506/3 (2005). 

Degtyareva VF, Degtyareva O, Mao H-K, Hemley RJ (2006) High-pressure behavior of CdSb compound decomposition, phase formation, and amorphization. Phys Rev B 73 214108 Marks NA, McKenzie DR, Padthorpe BA et al (1996) Microscopic structure of tetrahedral amorphous carbon. Phys Rev Lett 76 768-771... 

E. Tetrahedral Amorphous Carbon. Hard Amorphous Carbon... 

D.R. McKenzie, D. Muller, B.A. Pailthorpe, Compressive-stress-induced formation of thin-film tetrahedral amorphous-carbon. Phys. Rev. Lett. 67, 773 (1991)... 

Density can also be determined from EELS measurements. Xu et al. used electron energy-loss spectroscopy (EELS) to characterize hydrogen-free tetrahedral amorphous carbon films [65]. They studied several carbon film materials deposited with different bias voltages. From their results, it is possible to fit a good correlation between the density (Z>) of the carbon films tested and the maximum of the low loss plasmon peak ( p). Thus, Xu obtained an empirical relation as follows ... 

Raman spectra with UV excitation of tetrahedral amorphous carbon contain bands near 1100 cm" and 1600 cm due to sp and sp hybridised carbon respectively. Micro-Raman spectra were used to study carbon-based thin films obtained from camphor soot. There was evidence for diamond-like structures, graphite-like forms and tetrahedrally-coordinated carbon of the camphor soot. ... 

Nano crystalline diamond has a wide potential window of water stability, similar to that of diamond [29]. The current peak at +1.7 V vs. SHE, often found in voltammograms of polycrystalline diamond, is absent from these films. Yoo and co-workers reported that tetrahedral amorphous carbon, ta-C N, had a chemical stability similar to that of boron-doped diamond and a wider potential window for water stability [30]. The ta-C N electrodes were more catalytic for electron-transfer reactions than diamond electrodes, e.g., they exhibited reversible behavior with outer-sphere couples. These properties are believed to arise from the presence of sp2 carbon and nitrogen within the amorphous structure. 

---