Formation of carbide derived carbon coatings on SiC

Zarife Göknur Cambaz

doi:10.17918/etd-2527

Control over the structure of materials on nanoscale can open numerous opportunities for the development of materials with controlled properties. Carbon, which is one of the most promising materials for nanotechnology, can be produced by many different methods. One of the most versatile, in terms of a variety of structures demonstrated (graphite, porous amorphous carbon, nanotubes, graphene and diamond), is selective etching of SiC and other carbides. Since the Si atoms are extracted layer by layer, atomic level control of the carbon structures can potentially be achieved without changing the size and shape of the sample. Carbon produced by this method is called Carbide-Derived Carbon (CDC). In this work, CDC formation was studied on single crystalline 3C-SiC whiskers and 6H-SiC wafers by chlorination and vacuum decomposition at high temperatures with the goals to better understand the mechanism of carbide-to-carbon transformation and determine conditions for synthesis of desired carbon structures. The reaction kinetics, morphology and shape conservation were investigated at nanoscale. The transformation mechanism of the SiC surface to carbon was discussed in detail accounting to the effects of processing parameters (temperature, and composition of the environment), and material parameters (surface conditions, surface chemistry, crystal face, etc.). The characterization of the carbon structures was performed by using scanning electron microscopy (SEM), Raman spectroscopy and transmission electron microscopy (TEM). We compared chlorination of SiC whiskers with wet etching and showed that chlorination revealed the dislocations, while wet etching resulted in pagoda-like 3-D nanostructures upon selective etching of stacking faults (SFs). The difference in etching mechanisms was discussed. We determined the processing conditions for controlled synthesis of carbon structures like graphene, graphite and carbon nanotubes (CNTs) on the surface of [alpha]-SiC wafers by decomposition in low vacuum. CNT brushes grown on SiC showed good mechanical properties and high oxidation resistance. Moreover, we showed that patterns of graphite and catalyst-free nanotubes can be grown simultaneously and directly on a semiconductor SiC wafer. Devices built in this way can be used in applications from sensing to field emission.

Formation of carbide derived carbon coatings on SiC

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Formation of carbide derived carbon coatings on SiC

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