Influence of rf power on the properties of hydrogenated amorphous silicon carbon alloy films prepared by magnetron sputtering of silicon in methane-argon gas mixtures

Abstract

The rf power dependence of structural, optical, electrical, and optoelectronic properties of hydrogenated amorphous silicon carbon alloy films prepared by magnetron sputtering of silicon in methane-argon gas mixtures has been investigated. With increasing rf power, the optical band gap and the activation energy of dark conductivity decrease, accompanied by a decrease in the concentration of Si-C bonds. The dark conductivity and the photoconductivity increase with increasing rf power. These results are discussed in terms of the compositional and structural change of the films with rf power, such as the factor of preferential attachment of hydrogen to carbon deduced from IR measurements, and the conduction-band tail width deduced from optical absorption spectra or from temperature dependence of photoconductivity.