XPS Studies of a-Si1-xCx:H Prepared from C2H4/SiH4 Gas Mixtures

Abstract
Hydrogenated amorphous silicon carbon alloy films (a-Si1-x C x :H) with optical band gap 2.4 eV and x=0.5, deposited in a radio frequency (13.56 MHz) plasma of H2/C2H4/SiH4 gases have been examined using X-ray photoelectron spectroscopy (XPS). From the Cls and Si2p core level spectra it was found that films grown using a smaller SiH4/C2H4 ratio had a larger concentration of Si-C bonds. Further, spectrum shifts caused by slight Ar sputtering of as-deposited films suggested that the formation of Si-C bond occurs at the surfaces. Finally, valence band spectra showed that films with high Si-C bond density had a steep valence band edge typical of high quality films.