Alkoxy-type organic monolayers on hydrogen-terminated silicon were prepared from 1-undecanol (UN), 1-nonanol (NO), 1-heptanol (HP), and 4-phenylphenenol (PP). These monolayers were characterized based on x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). XPS spectra showed that the lowest amount of SiOx oxide on the sample of the UN monolayer. On the other hand, a SiOx peak was clearly observed for the HP, NO, and PP monolayers. The generation of SiOx in the PP monolayer may have been due to steric hindrance of the aromatic rings. The-CH2-region in the FT-IR spectra showed that shorter alkyl chains promoted the formation of gauche conformers in the monolayer. This increase of gauche conformers was determined to have caused the generation of SiOx in the alkyl monolayers. (C) 2004 American Vacuum Society.