Chemical vapour deposition silicon carbide

Fitzer E, Hegen D, Strohmeier H (1979) Chemical vapor deposition of silicon carbide and silicon nitride and its application for preparation of improved silicon ceramics. In Sedgwick TO, Lydtin H (eds) Proceedings of the 7th international conference on chemical vapour deposition, Los Angeles. Electrochemical Society, Pennington, NJ, pp525-535... 

Allendore MD, Osterheld TH (1995) Modeling the gas-phase chemistry of silicon carbide formation. In Gallois BM, Lee WY, Pickering MA (eds) Chemical vapour deposition of refractory metals and ceramics III. Materials Research Society, Pittsburgh, PA, pp39 14... 

Stinespring CD, Wormhoudt JC (1989) Surface studies relevant to silicon carbide chemical vapour deposition. J Appl Phys 65 1733-1742... 

Microstructure of Chemical Vapour Deposition SiC Figure 6.8 shows the X-ray diffraction (XRD) patterns of CVD SiC deposited in a temperature range of 1000 to 1300°C. Detailed analyses of the X-ray results indicate that the deposits are pure silicon carbide mainly composed of //-SiC (cubic 3C crystal structure) with a small amount of er-SiC (hexagonal 4H crystal structure). It is clear from the figure that the diffraction angles of 35.6°, 41.3°, 60.1°, 72.1° and 75.5° correspond to //-SiC and the diffraction angle of 33.7° corresponds to er-SiC. As the deposition temperatures decrease, the deposits become poorly crystallised because the diffraction peaks become broader or its intensity shown in Y axis become lower. At the deposition temperature of 1000°C, the deposits are in a quasi-amorphous state. 

Kingon AI, Lutz LJ, Liaw P, Davis RF (1983) Thermodynamic calculations for the chemical vapour deposition of silicon carbide. J Am Ceram Soc 66 558-566... 

Thermal oxidation of the two most common forms of single-crystal silicon carbide with potential for semiconductor electronics applications is discussed 3C-SiC formed by heteroepitaxial growth by chemical vapour deposition on silicon, and 6H-SiC wafers grown in bulk by vacuum sublimation or the Lely method. SiC is also an important ceramic ana abrasive that exists in many different forms. Its oxidation has been studied under a wide variety of conditions. Thermal oxidation of SiC for semiconductor electronic applications is discussed in the following section. Insulating layers on SiC, other than thermal oxide, are discussed in Section C, and the electrical properties of the thermal oxide and metal-oxide-semiconductor capacitors formed on SiC are discussed in Section D. 

In the case of glass, however, no great variations in behaviour between different types are expected because of their very similar structure and surface composition. Chemical vapour deposition reactions had already been tried by the last century, for instance in the refinement and deposition of silicon by reduction of SiF4 and SiCU with alkali metals [71] and in the refining of Ni using Ni-carbonyl in the Mond process [72,73]. The major impact of chemical vapour deposition on thin-film technology took place, starting some 60 years ago, when refractory compounds such as metal carbides, nitrides, silicides, borides and oxides as well as mixed phases of... 

Conversion of activated carbon into porous silicon carbide by fluidized bed chemical vapour deposition... 

A new preparation method is described to synthesize porous silicon carbide. It comprises the catalytic conversion of preformed activated carbon (extrudates or granulates) by reacting it with hydrogen and silicon tetrachloride. The influence of crucial convoaion parameters on support properties is discussed for the SiC synthesis in a ftxed bed and fluidized bed chemical vapour deposition reactor. The surface area of the obtained SiC ranges ftiom 30 to 80 m /g. The metal support interaction (MSI) and metal support stability (MSS) of Ni/SiC catalysts are compared with that of conventional catalyst supports by temperature programmed reduction. It is shown that a Ni/SiC catalyst shows a considnable Iowa- MSI than Ni/Si(>2- and Ni/Al203-catalysts. A substantially improved MSS is observed an easily reducible nickel species is retained on the SiC surface after calcination at 1273 K. 

The MFEs are coated particles similar to TRISO fuel with the outer diameters of about 2 mm. They consist of 1.5-1.64 mm diameter uranium dioxide spherical kernels coated with 3 ceramic layers. The inner layer, called a buffer layer, is made of 0.09 mm thick porous pyrolythic graphite (PyC) with the density of 1 g/cm, providing space for gaseous fission products. The second layer is made of 0.02 mm thick dense (1.8 g/cm ) PyC, and the outer layer is 0.07-0.1 mm thick corrosion resistant silicon carbide (SiC). The fourth, outer PyC layer is assumed to be absent. SiC protection layers, manufactured by chemical vapour deposition (CVD) method, create resistance of graphite components against water and steam at high temperatures. Small fuel elements are able to confine fission products indefinitely at temperatures below 1600°C. 

For a variety of SiCf/SiC type composites, it has been stated that the SiC matrices are more creep resistant than the Nicalon fibres. " This conclusion was reached on the grounds that the creep rates reported for silicon carbide produced by chemical vapour deposition appeared to be lower than the rates predicted by extrapolation of results obtained for Nicalon fibres. However, it is a simple matter to demonstrate that the fibres rather than the matrices control the creep strength of both the standard SiCf/SiC and enhanced SiCf/SiC composites. 

Weiss J R, Diefendrof R J, Chemically vapour deposited SiC for high temperature and structural applications , Silicon Carbide-1973, University of South Carolina Press, Columbia, SC, 1973, 80-91. 

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