Interaction of hot Si(1 0 0)2×1 with water vapour

Abstract

The interaction of H 2O with Si(1 0 0)2×1 surface, maintained at 350 °C, has been analysed by LEED, AES, and photoemission yield spectroscopy (PYS). The water vapour is adsorbed dissociatively on H and O. The oxygen atom breaks the dimers that induce the creation of new dangling bonds, which have been passivated by oxygen. The hydrogen atom is bonded to the dangling bonds of the dimers. The initial sticking coefficient is S 0 = 0.1 , this value is lower than that found at room temperature (approximate unit). Then the temperature reduces the reaction of the silicon surface with water vapour and does not favour the diffusion of oxygen into the bulk, like the one that has been found in H 2O/Si at room temperature where the resulting oxygen atom starts with an insertion into the first surface layers Si atom and breaks the Si–Si back-bonds. After surface passivation by H 2O, the valence band has been fitted by a power law ( E– E i) 2.5; E i=(5.18±0.02) eV. The m and E i values indicate that the silicon surface brings about a scattering of photoemitted electrons. This scattering is attributed to the dipole effect, introduced by water vapour adsorption, and is distributed in a non-uniform way on the silicon surface.