MICROVOIDS IN DIAMOND-LIKE AMORPHOUS-SILICON CARBIDE

The correlation between composition, microstructure, and optical prope rties of a-Si1-xCx:H thin films with different stoichiometries was est ablished. The alloys were deposited by radio frequency glow discharge under ''starving'' plasma conditions from mixtures of SiH4 and CH4. Th e samples were characterized by small angle x-ray scattering, ultravio let-visible and infrared spectrometry, and Auger electron spectroscopy . The results showed the presence of microvoids with sizes between sim ilar or equal to 3 Angstrom and similar or equal to 8 Angstrom. The re lative microvoid volume fraction displayed a maximum for x around 55 a t. % and decreased for higher values of x. High carbon content alloys (x similar or equal to 70 at. %) not only have a lower relative microv oid volume fraction, but show optical gaps as high as 3.7 eV, high res istivity, and very low refractive index, indicating the presence of a diamond-like C-C structure. These remarkable results are attributed to the deposition under ''starving'' plasma conditions.