Thermodynamics, kinetics, and microstructure of laser chemical vapor deposition of SiC

Thermodynamic and kinetic analyses as well as extensive experimentation were used to better understand the laser chemical vapor deposition of silicon carbide (SiC). The thermodynamic calculations suggested the use of lower processing temperatures, which experimentally proved advantageous for growth of uniform SiC fibers. The apparent activation energy was 163 KJ/mol, and the order of reaction with respect to the concentration of methyltrichlorosilane (MTS) was 0.36. Characterization via scanning electron microscopy revealed the deposits to be polycrystalline. Elongated grains oriented in the growth direction had aspect ratios in the range of 4-32 with diameters of 2-50 mu m, depending on the deposition temperature. Temperature had a larger effect on the deposition rate and microstructure than did the H-2/MTS ratio.