Carbon films, diamond-like optics

Plasma Synthesis The use of plasma methods has lead to a new range of materials having unique properties. An example is the family of amorphous elemental hydrides (eg cr-C H Of -Si H or-P H) which contain a variable proportion of H from almost zero to 50 atomic %. The carbon films, known variously as "hard carbon", "diamond-like carbon", " a-carbon" etc (9 ) - These layers are of considerable interest because of their optical and abrasion-resistant properties etc (Table I). The properties of these Gr-carbon films, can be tailored by modifying the plasma parameters. 

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. 

Franta, D. Ohlidal, I. Bursikova, V. Zajickova, L. Optical properties of diamond-like carbon films containing SiOx. Diamond Relat. Mater. 2003, 12, 1532-1538. 

The main idea of the EIB-CVD method developed by a group of Japanese researchers (Matsui et al. 20(X)) is the scanning of a given image introduced into a computer by a Ga+ ion beam with the ion energy of 30 keV and a beam diameter of 5 nm. The method uses vapors of the precursor, for example, phenanthrene C,4H,o, that are deposited on the substrate and form a carbon film, whose thickness depends on the absorbed radiation dose. The spectral analysis of the film shows that it consists of amorphous carbon having a tetrahedral (sp ) structure inherent to diamond (diamond-like amorphous carbon, DEC) and has high hardness, chemical inertia, and optical transparency (Matsui 2007). 

The carbon clusters afford some interesting optical properties to the SiOC and Sic films [79], but are also responsible for the high hardness measured on irradiated films (see Table 4), This is at least two times larger than that of eonventionally annealed specimens, mainly because of the previously mentioned diamond-like nature of the C precipitates in the amorphous SiOC or SiC ceramic matrix of irradiated specimens. The effect depends on the type of irradiating ion, but also on the nature of the side groups of the polymeric chain (CH3 vs. C6H5) [59,60]. The annealing of irradiated films does not seem to affect much their hardness. 

An effective medium approximation (EMA) has been applied to determine the optical constant of amorphous carbon where the entire film is considered as a composite heterogeneous medium of amorphous diamond-like carbon, amorphous graphite polymeric carbon, and voids. The EMA expression for the dielectric function e, of the composite medium can be expressed as... 

Wear resistance Cutting tools, machine parts Electric parts, optical parts TiC, TiN, Ti(C, N), (Ti, A1)N CrN, Cr,C3, AI2O3, SiOj W2C, TiB2, diamond Diamond-like carbon Cemented carbide Quenched and tempered steel, stainless steel, Ti alloy, A1 alloy, PET film Plastic lens... 

It turned out that the admixture of sp2-carbon exerts a decisive effect on the electrode quality of diamond films. And yet, modern physical and optical experimental techniques, like Raman and Auger spectroscopy, AFM, etc., failed in the elucidation of subtle effects exerted by the admixture of non-diamond carbon on the behavior of polycrystalline diamond films it is the electrochemical measurements that give plausible information [22] (see Section 6.3). 

---