POLYCRYSTALLINE SILICON-CARBIDE FILMS DEPOSITED BY LOW-POWER RADIOFREQUENCY 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 alpha-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 (approximately 10 S/cm) and Hall mobility [approximately 10 cm2/(V s)] for either carrier type. The conductivity is seen to be independent of thickness down to approximately 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.