Co-deposition of diamond and β-SiC by microwave plasma CVD in H2-CH4-SiH4 gas mixtures

The co-deposition of diamond and silicon carbide (SiC) was realized in a microwave plasma using H-2-CH4-SiH4 mixtures at enhanced microwave power density of up to 150 W/cm(3), and SiC/diamond composite films on (100) Si substrates were produced. The growth parameters were selected to ensure almost equal deposition rates of similar to 0.3 mu m/h for both phases. Composite films were formed either directly on Si surface, or on a buffer (nucleation) layer of SiC or diamond, preliminary deposited on the Si substrate. The film structure has been characterized by SEM, XRD, Raman and PL spectroscopy. It was confirmed that the silicon carbide phase in the composite is the cubic polytype beta-SiC (3C-SiC) with the presence of only a small fraction of the hexagonal polytype, while the diamond is in well-faceted microcrystalline form. Diamond grains are Si-doped as was evidenced by the strong photoluminescence of silicon-vacancy color centers. Also, minor inclusions of amorphous sp2 carbon and of trans-polyacetylene (t-PA) were detected in the beta-SiC phase. The overall crystalline quality of the composite is high, as evidenced by narrow Raman peaks both for diamond and beta-SiC. Our results show, that with an appropriate choice of growth parameters, particularly SiH4/CH4 ratio, high-quality films of Si-doped diamond, silicon carbide, SiC-diamond composite, and combinations of these structures can be synthesized in a single process. Prime novelty statement The co-deposition of diamond and SiC was realized by microwave plasma CVD using H-2-CH4-SiH4 mixtures at enhanced microwave power density; beta-SiC/diamond composite films were produced with high crystalline quality on (100) Si substrates.