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Nanostructual properties of amorphous silicon carbide by GISAX and optical spectroscopy

Nonstehiometric hydrogenated amorphous thin films were deposited by magnetron sputtering in wide range of hydrogen and carbon concetration and anlysed by vibrational spectroscopy and GISAXS (Grazin Incidence Small Angle X-ray Scattering). The film compositon and density were estimated by IBA (Ion Beam Analysis), in particulary RBS (Rutherford Backscattering Spectrometry) and ERDA (Elstic Recoil Detection Analysis). It was found that increasing carbon and hydrogen concentration, the film density decrese. Assuming that the density decrese is mostly a consequence of increse in voids contribution, by using efective medium approximation, optical properties in infra red part of spectra were used as a probe for voids size and theirs volume contribution. By using previously proposed (published) model calculaction, it was found that the individual voids sizes increse with hydrogen and carbon content and the voids size distribution broadens. In order to check above asumption and model calculation, the GISAXS was performed on ELETTRA synchrotron radiation source, Trieste (Italy). In order to avoid influence of surface roughness, spectra were taken under several incident angles. The obtained results show presence of two types of structural futures with different sizes. The smaller ones have dimensions between 1-2 nm and can be indentifay as voids. The larger ones hve 10 nm large "particles" on distance of 40 nm. This "superstructure" could be analogue of "columnar growth" for polycrystalline samples or SiC "macroscopic" phase.

nanostructure; amorphous silicon carbide; ion beam analysis; GISAXS

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