Aluminum doping and dielectric properties of silicon carbide by CVD

Cubic β-SiC coating was grown onto the graphite substrate by the normal pressure chemical vapor deposition using CH3SiCl3(MTS) as a source precursor at 1 150 ℃. But the hexagonal Al4SiC4 phase was generated in the doped process with trimethylaluminium(TMA) as the dopant. Microstructure of the deposit coating as-prepared was characterized by scanning electron microscope(SEM),which consists of spherical particles with a very dense facet structure. The real component of permittivity ε′ and dielectric loss tanδ of the coatings undoped and doped by TMA were carried out by a vector network analyzer in the microwave frequency ranges from 8.2 GHz to 12.4 GHz. The results show that both of them have low values,and doped coating has lower ε′ and tan δ than undoped one due to the existence of Al4SiC4 impurity phase,which indicates that the desired Al/SiC solid solution at 1 150 ℃ in a normal argon atmosphere is not produced.

Cubic β-SiC coating was grown onto the graphite substrate by the normal pressure chemical vapor deposition using CH3SiCl3 （MTS） as a source precursor at 1 150 ℃. But the hexagonal Al4SiC4 phase was generated in the doped process with trimethylaluminium （TMA） as the dopant. Microstructure of the deposit coating as-prepared was characterized by scanning electron microscope （SEM）, which consists of spherical particles with a very dense facet structure. The real component of permittivity ε＇ and dielectric loss tang of the coatings undoped and doped by TMA were carried out by a vector network analyzer in the microwave frequency ranges from 8.2 GHz to 12.4 GHz. The results show that both of them have low values, and doped coating has lower ε＇ and tan δ than undoped one due to the existence of Al4SiC4 impurity phase, which indicates that the desired Al/SiC solid solution at 1 150 ℃ in a normal argon atmosphere is not produced.