Low temperature direct growth of nanocrystalline silicon carbide films

Hydrogenated silicon carbide thin films have been grown directly by reactive magnetron co-sputtering of Si and C targets in a pure hydrogen plasma at substrate temperatures, TS, ranging between 300 and 700°C. The results reveal the achievement of nanocrystalline SiC at a deposition temperature of 400°C, the lowest temperature ever reported for the sputtering method. Both intensity increase and peak narrowing of the lorentzian infrared absorption band at ∼800 cm−1 ascribed to Si–C bonds in the crystalline state, are indicative of the continuing improvement of the crystallinity when TS is increased beyond 400°C. According to the X-ray photoelectron spectroscopy (XPS) measurements, the SiC layers are carbon rich with an atomic ratio C/Si approaching 1.15 for TS≈400–600°C. The Si atoms are found, however, tetracoordinated with only the C atoms, in perfect agreement with the Raman data that exclude the formation of amorphous or crystalline Si, even though they report the presence of excess carbon. The high resolution electron microscopy observations clearly indicate the formation of randomly oriented SiC crystals of the cubic phase at TS≥400°C with an average size of a few nanometers.