Adsorption of water on alkoxy modified Si(100), Si(113) and Si (115) surfaces

The passivation of Si(1 0 0), Si(1 1 3) and Si(1 1 5) with ethanol, isoprop anol and tert-butanol has been studied with high resolution electron energy loss spectroscopy (HREELS) and low electron energy diffraction (LEED). The HREEL spectra show clearly that the alcohols chemisorb dissociatively with the formation of a Si-O-C linkage on the three surfaces. We observe a cons iderable chemisorption of water on the ethoxy and tert-butoxy passivated Si (1 0 0)-2 x 1 surfaces. From the disappearance of the 2 x 1 LEED pattern, i t can be concluded that the chemisorption of water occurs through a cleavag e of the Si-Si dimer bond. In contrast, isopropoxy species on Si(1 0 0)-2 x 1 reduces dramatically the reactivity towards water. However, Si(1 1 3) an d Si(1 1 5) turn out to be much more reactive towards water molecules after the adsorption of any of the alcohols. (C) 2001 Elsevier Science B.V. All rights reserved.