Polycrystalline silicon carbide films deposited by low-power radio-frequency plasma decomposition of SiF4-CF4-H2 gas mixtures

Polycrystalline silicon carbide thin films have been deposited on amorphous substrates by radio-frequency plasma-assisted decomposition of tetrafluoro silane, tetrafluoro methane, and hydrogen gas mixtures using low-power density and deposition temperatures. The material is shown to possess the α-SiC structure using transmission electron microscopy. It has highly visible transmittance and exhibits bands due to silicon carbide as well as fluorine bonded to carbon and silicon in the infrared transmission spectra. It is easily doped, both types showing high conductivity (∼10 S/cm) and Hall mobility [∼10 cm2/(V s)] for either carrier type. The conductivity is seen to be independent of thickness down to ∼10 nm when deposited on glass. This behavior and the dependence of both structural and electronic properties on deposition parameters is discussed in terms of the chemical reactions in gas phase and on the growth surface.