Silicon Carbide SilCor®SiC (a-C1-xSix:H, a-C1-xSix:O:H)
The thin films grown by means of Plasma-CVD technology from a hydrocarbon - silane gas mixture are referred to as hydrogenated amorphous silicon-carbon alloys. These films or - synonymously - coatings show physical and chemical properties which are much more similar to DLC than to crystalline silicon carbide. The latter, crystalline modification is widely used as technical ceramics or semiconductor material since many years. Because of the option to change the content x of the element silicon, SilCor®SiC coatings have a broad variety of properties. Therefore, the optimum composition of the films may be different for specific applications. The silicon content of the films ranges between a few percent (these films are also referred to as DLC:Si) and about 50 % according to stoichiometric composition. The various silicon contents x are realized by changing the ratio of the hydrocarbon and silane gas during the Plasma-CVD process.
Another measure to modify the properties of SilCor®SiC silicon carbide coatings is the addition of oxygen. Films prepared with oxygen show an especial low free surface energy down to 20 mN/m. Their wetting behavior hence is similar to PTFE. However, their hardness exceeds those of Teflon by orders of magnitude. In addition, films alloyed with oxygen show a higher optical transparency than unalloyed SiC.
left: film of a-C0.95Si0.05:H, thickness 0,1 µm, deposition temperature 50 deg C
right: film of a-Si0.29C0.71:H, thickness 1,4 µm, deposition temperature 260 deg C.
The elemental composition was measured by means of a SIMS in-depth profile, the film surface is at t=0.
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