Structures diamond-like carbon

A new form of carbon coating is now available which is neither diamond nor graphite and is known as diamond-like carbon (DLC).bl DLC can be considered as a metastable carbon produced as a thin coating with a broad range of structure and composition.l b[42]... 

Zhenyu Zhang, Xinchun Lu, Jianbin Luo, Yang Liu, Chenhui Zhang, Preparation and Characterization of Fa203 Doped Diamond-Like Carbon Nanofilms (I) Structure Analysis," Diamond Relat. Mater., Vol. 16, No. 11, 2007, pp. 1905-1911. 

Raman spectroscopy A nondestructive method for the study of the vibrational band structure of materials, which has been extensively used for the characterization of diamond, graphite, and diamond-like carbon. Raman spectroscopy is so far the most popular technique for identifying sp bonding in diamond and sp bonding in graphite and diamond-like carbon. 

Since the main parameter influencing diamond-like carbon film structure is the energy of bombarding ions, it is expected that the same happens with a-C H films. In fact, it was found that in RFPECVD deposition of a-C H films, the variation of substrate self-bias results in strong changes of film growth, composition, structure, and properties. 

K. H. Er, S. G. So, The mechanical and structural properties of Si doped diamond-like carbon prepared by reactive sputtering., Journal of Ceramic Processing Research, vol. 12, pp. 187-190, 2011. 

Figure 9.34 Characteristic spectra of carbon in different structures (a) highly oriented graphite (b) polycrystalline graphite (c) amorphous carbon and (d) diamond-like carbon. (Reproduced with permission from G. Turrell and J. Corset, Raman Microscopy, Developments and Applications, Academic Press, Harcourt Brace Company, London. 1996 Elsevier B.V.)...

Diamond-like carbon since its inception in 1962 has found applications in some very important areas. These applications include coatings used in scratch-resistant optics, razor blades, prosthesis in medical applications electron emission surfaces in electronics as an insulator material for copper heat sinks in semiconductors such as solar cells and sensors for visible to infrared radiations and as structural materials such as deuterated DLC film used for neutron storage in advanced research instrumentation. As technology matures the unique properties of DLC will find new and important applications. 

Figure 11.20 shows the influence of electron beam irradiation with =100keV in a transmission electron microscope on thin film structure during 2 s of deposition. As can be seen in Figure 11.20 the electron irradiation of the film results in its amorphization, as the main maximum at d= 0.435 nm attributing to the linear chain structure disappears the film structure transforms into diamond-like carbon. This means that the electron beam excitation of carbon atoms leads to cross-linkages among carbon chains and, as a result, the transformation of sp bonds into sp" and sp" bonds takes place. 

This general scheme of surface nucleation processes, as described above, may be adequate only for nucleation on a perfect substrate. It is well known that in many important practical situations, nucleation occurs at defect sites on the substrate surface. In addition, the interactions of gas-phase species with the substrate surfece in diamond CVD may lead to surface carbon atoms of different chemical bonding states and structures, for example, sp, sp, or sp bonded carbon, amorphous carbon, diamond-like carbon or carbon in carbides. These factors further increase the difficulty in understanding surface nucleation processes of diamond in CVD. 

On an atomic scale, the majority of carbons exhibit the allotropic form of graphite, i.e. a sp -based structure, while diamond-like carbons, fullerenes and their derivatives, such as nanotubes, represent a shorter variety of carbon forms. However, depending on the degree of... 

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